Brief, intense exercise benefits the heart
Short bursts of high intensity sprints—known to benefit muscle and improve exercise performance—can improve the function and structure of blood vessels, in particular arteries that deliver blood to our muscles and heart, according to new research from McMaster University.
The study, lead by kinesiology doctoral student Mark Rakobowchuk, is published online in the journal American Journal of Physiology. Regulatory, Integrative & Comparative Physiology.
The findings support the idea that people can exercise using brief, high-intensity forms of exercise and reap the same benefits to cardiovascular health that can be derived from traditional, long-duration and moderately intense exercise.
"As we age, the arteries become stiffer and tend to lose their ability to dilate, and these effects contribute to high blood pressure and cardiovascular disease," says Maureen MacDonald, academic advisor and an associate professor in the Department of Kinesiology. "More detrimental is the effect that blood vessel stiffening has on the heart, which has to circulate blood".
The research compared individuals who completed interval training using 30-second "all-out" sprints three days a week to a group who completed between 40 and 60 minutes of moderate-intensity cycling five days a week.
It found that six weeks of intense sprint interval exercise training improves the structure and function of arteries as much as traditional and longer endurance exercise with larger time commitment.
"More and more, professional organizations are recommending interval training during rehabilitation from diseases like chronic obstructive pulmonary disease, peripheral artery disease and cardiovascular disease. Our research certainly provides evidence that this type of exercise training is as effective as traditional moderate intensity training," says MacDonald. "We wouldn't be surprised to see more rehabilitation programs adopt this method of training since it is often better tolerated in diseased populations".
Further, this research also shows that those who have a hard time scheduling exercise into their life can still benefit from the positive effects, if they are willing to work hard for brief periods of time, she says.
Daily exercise dramatically lowers men's death rates
American Heart Association rapid access journal report:
Increased exercise capacity reduces the risk of death in African-American and Caucasian men, researchers reported in Circulation: Journal of the American Heart Association.
The government-supported Veterans Affairs study included 15,660 participants and is the largest known to assess the link between fitness and mortality.
“It is important to emphasize that it takes relatively moderate levels of physical activity — like brisk walking — to attain the associated health benefits. Certainly, one does not need to be a marathon runner. This is the message that we need to convey to the public,” said Peter Kokkinos, Ph.D., lead author of the study and director of the Exercise Testing and Research Lab in the cardiology department at the Veterans Affairs Medical Center in Washington, D.C.
Professor Kokkinos and colleagues investigated exercise capacity as an independent predictor of overall mortality for African-American men (6,749) and Caucasian men (8,911) and also examined whether racial differences in exercise capacity influence the risk of death. Veterans were tested by a standardized treadmill test to assess exercise capacity between May 1983 and December 2006 at Veterans Affairs medical centers in Washington, D.C., and Palo Alto, Calif. The men were encouraged to exercise until fatigued unless they developed symptoms or other indicators of ischemia. These individuals were then followed for an average of 7.5 years and death rates were recorded.
Researchers classified the subjects into fitness categories based on their treadmill performance, expressed as peak metabolic equivalents (METs) achieved. Technically, a MET is equivalent to oxygen consumption of 3.5 milliliters per kilograms of body weight per minute. One MET represents the amount of oxygen the person uses at rest. Anything above one MET represents work. The higher the MET level achieved, the more fit the individual.
Based on this concept, the researchers divided the participants into four categories:
0. 3,170 men were “low fit,” achieving less than 5 METs;
0. 5,153 men were “moderately fit,” achieving 5 to 7 METs;
0. 5,075 were “highly fit,” achieving 7.1 to 10 METs; and
0. 2,261 were “very highly fit,” achieving more than 10 METs.
The study found that “highly fit” men had half the risk of death compared to “low fit” men. Men who achieved “very highly fit” levels had a 70 percent lower risk of death compared to those in the “low fit” category. For every 1-MET increase in exercise capacity (fitness), the risk for death from all causes was 13 percent for both African Americans and Caucasians.
Kokkinos said, “These findings are important for several reasons: First, we were able to quantify the health benefits per unit increase in exercise capacity. Second, this is the first study to provide information on physical activity and mortality in African Americans, information lacking until now. Keep in mind that death rates in African Americans are much higher when compared with Caucasians, in part because race and income negatively influence access to healthcare.”
“The Veterans Affairs’ health system is unique in that it ensures equal access to care regardless of a patient’s financial status,” he added. “Thus, it provides us with a unique opportunity to assess the impact of exercise or physical activity on death without the influence of healthcare differences.”
According to Kokkinos, most middle-age and older individuals can attain fitness levels with a brisk walk, 30 minutes per day, five to six days each week. “I do not advocate that everyone can start with 30 minutes of physical activity. In fact, 30 minutes may be too much for some people. If this is the case, split the routine into 10-15 minutes in the morning and another 10-15 minutes in the evening. The benefits will be similar if the exercise volume accumulated is similar,” he said.
“Our findings show that the risk of death is cut in half with an exercise capacity that can easily be achieved by a brisk walk of about 30 minutes per session 5-6 days per week,” he added. “Physicians should encourage individuals to initiate and maintain a physically active lifestyle, which is likely to improve fitness and lower the risk of death. Individuals should also discuss exercise with their physician before embarking on an exercise program.”
Moderate level of aerobic fitness may lower stroke risk
Abstract 119
A moderate level of aerobic fitness can significantly reduce stroke risk for men and women, according to a large, long-running study presented at the American Stroke Association’s International Stroke Conference 2008.
“Fitness has a protective effect regardless of the presence or absence of other stroke risk factors, including family history of cardiovascular disease, diabetes, high blood pressure, elevated cholesterol levels and high body mass index,” said Steven Hooker, Ph.D., the study’s lead author.
“This study is the first to suggest that there may be a significant independent association between cardiorespiratory fitness (CRF) and fatal and nonfatal stroke in men and nonfatal stroke in women,” said Hooker, director of the Prevention Research Center at the University of South Carolina Arnold School of Public Health, Columbia, S.C.
About 780,000 U.S. adults suffer a stroke each year, and stroke is a leading cause of serious, long-term disability in the United States, according to the American Stroke Association. It’s often fatal, claiming about 150,000 lives and ranking as the No. 3 cause of death. Researchers analyzed data on more than 60,000 people — 46,405 men and 15,282 women who participated in the Aerobics Center Longitudinal Study between 1970 and 2001 at the Cooper Aerobics Center in Dallas. The participants, ages 18 to 100 and free of known cardiovascular disease when they entered the study, were followed for an average of 18 years. During that time, 863 people — 692 men and 171 women — had strokes.
Upon entering the study, each participant took a test to measure CRF in which they walked on a treadmill at increasing grade and/or speed until they reached their maximal aerobic capacity.
Although many previous studies have looked at an association between self-reported physical activities and cardiovascular disease, few have used direct measurements such as the CRF measure used in this study, Hooker said. This is also the first study to explore the association between CRF and risk of stroke in women.
Men in the top quartile (25 percent) of CRF level had a 40 percent lower relative risk of stroke compared to men in the lowest quartile. That inverse relationship remained after adjusting for other factors such as smoking, alcohol intake, family history of cardiovascular disease, body mass index (an estimation of body fatness), high blood pressure, diabetes and high cholesterol levels, he said.
Among women, those in the higher CRF level had a 43 percent lower relative risk than those in the lowest fitness level.
The overall stroke risk dropped substantially at the moderate CRF level, with the protective effect persisting nearly unchanged through higher fitness levels. That corresponds to 30 minutes or more of brisk walking, or an equivalent aerobic activity, five days a week.
“We found that a low-to-moderate amount of aerobic fitness for men and women across the whole adult age spectrum would be enough to substantially reduce stroke risk,” Hooker said.
“Although stroke death rates have declined over the past few decades, the public health burden of stroke-related disabilities continues to be large and may even increase in coming years, as the population ages.”
Physical activity is a major modifiable cardiovascular disease risk factor. Increasing the nation’s CRF through regular physical activity could be a vital weapon to lower the incidence of stroke in men and women, he said.
One of the study’s limitations is that most of the participants were white, well-educated and middle-upper income, he said. He recommended that data be collected from other populations.
Walking Is Good
These days, it’s easy for people to get confused about exercise -- how many minutes a day should they spend working out, for how long and at what exertion level? Conflicting facts and opinions abound, but one Mayo Clinic physician says the bottom line is this: walking is good, whether the outcome measurement is blood pressure, diabetes, cardiovascular disease, joint problems or mental health.
“Getting out there and taking a walk is what it’s all about,” says James Levine, M.D., Ph.D., and a Mayo Clinic expert on obesity. “You don’t have to join a gym, you don’t have to check your pulse. You just have to switch off the TV, get off the sofa and go for a walk.”
The health benefit associated with walking is the subject of Dr. Levine’s editorial in the July issue of Mayo Clinic Proceedings. Dr. Levine’s piece is entitled, “Exercise: A Walk in the Park?” and accompanies a Proceedings article that showcases the merits of walking as beneficial exercise.
The study, undertaken by physicians from the Shinshu University Graduate School of Medicine in Matsumoto, Japan, determined that high-intensity interval walking may protect against high blood pressure and decreased muscle strength among older people.
Over five months, the Japanese researchers studied 246 adults who engaged in either no walking or moderate to high-intensity walking. The group who engaged in high-intensity walking experienced the most significant improvement in their health, the researchers found.
In his editorial, Dr. Levine says the study lends credence to the notion that walking is a legitimate, worthy mode of exercise for all people. Dr. Levine says it’s a welcome message for his patients, who fight obesity and appreciate that a walk is one way to improve their health.
Unlike a health club membership or personal trainer, walking “is there for everyone,” Dr. Levine says. “Walking doesn’t cost you anything, you can do it barefoot and you can do it now, this minute.”
“Sitting is bad for cholesterol, it’s bad for your back and muscles,” Dr. Levine says. “It’s such a terrible thing for our bodies to do and the less of it you do, the better. But activity is not easy. If it were easy, everyone would do it.”
A Walk a Day Might Help Keep the Doctor Away
New research reported in the Journal of the American Medical Association shows daily, mild exercise - walking or bike riding - improves the fitness of post-menopausal women who are currently sedentary, overweight or obese.__Timothy Church, M.D., Ph.D., of the Pennington Biomedical Research Center, led a team of researchers who examined the effect of various amounts of walking on more than 460 women. The results showed that as little as 15 minutes a day, five days a week of walking on a treadmill or riding a stationary bike improved fitness. __"The level of walking we studied was so light most people would not consider it exercise," Church said, "The message for women here is just get up and walk. You don't need a gym, you don't need fancy clothes or a stop-watch. All you need is a pair of comfortable shoes that you can walk in."__The women were randomly placed into one of four groups: a control group that did not exercise and groups that exercised 72 minutes, 135 minutes, or 191 minutes of exercise per week. Church's team found that the more exercise performed the greater the increase in fitness, which was expected. However, the lowest exercise groups also saw improvements in fitness, which the team did not expect. __"The surprising news," Church said, "is that the lowest exercise group showed significant improvement. We continue to recommend 30 minutes a day of walking at least five days a week, but the data suggests just doing something - even 15 minutes a day - is better than nothing.
Study explains how exercise lowers cardiovascular risk
It is well known that physical activity can improve cardiovascular health. But itis the impact exercise has on specific known risk factors that accounts for about 60 percent of that improvement, researchers reported in Circulation: Journal of the American Heart Association.
In a major study of over 27,000 women in the Womenis Health Study, researchers assessed a variety of risk factors and different levels of exercise in women who were followed for 11 years for new diagnosis of heart attack and stroke.
¡°Regular physical activity is enormously beneficial in preventing heart attack and stroke,¡± said Samia Mora, M.D., lead author of the study and instructor of medicine at Harvard Medical School in the divisions of preventive and cardiovascular medicine at Brigham and Womenis Hospital, Boston Mass. ¡°We found that even modest changes in risk factors for heart disease and stroke, especially those related to inflammation/hemostasis and blood pressure, can have a profound impact on preventing clinical events. This study is the first to examine the importance of a variety of known risk factors in explaining how physical activity prevents heart disease and stroke.¡±
The women ranged from 45 to 90 years old (average age 55) and were assessed for a full range of risk factors and different levels of exercise. There was a 40 percent reduction in heart attack and stroke between the highest and lowest exercise groups. The women self-reported physical activity, weight, height, hypertension and diabetes.
The long-term benefits of exercise start at a relatively low level, 600 kilocalories per week, equivalent to about two hours of physical activity per week, Mora said.
The study measured levels of a variety of traditional and novel risk factors to help understand the mechanisms that reduce risk for heart attack and stroke. Novel risk factors are emerging clinical, biochemical, and genetic markers that researchers have studied in order to better understand the development of a disease, to improve disease risk prediction, and to identify new targets for treatment.
Inflammatory and hemostatic biomarkers ¡ª fibrinogen, C-reactive protein and intracellular adhesion molecule-1 ¡ª together made the largest contribution to lower risk, 33 percent.
Blood pressure was the next major contributor to lower risk, 27 percent, followed by lipids, body mass index, glucose abnormalities, with minimal contribution from measures of renal function or homocysteine.
Inflammatory and hemostatic biomarkers are novel risk factors that relate to blood vessel function and inflammation of the arteries.
¡°Inflammatory and hemostatic factors as a group have overlapping functions and roles and, in our study, had the biggest effect in mediating exercise-related cardioprotection, more so than blood pressure or body weight,¡± Mora said. The study population was divided into four groups by levels of exercise:
• The highest level expended greater than or equal to 1,500 kilocalories per week (kcal/week) representing greater than five hours of moderately intense physical activity (such as brisk walking) per week.
• The next group expended from 600 to 1,499 kcal/week which reflected about two to five hours of physical activity per week.
• A third group represented an expenditure of 200 to 599 kcal/week, which is about one to two hours of physical activity per week.
• The reference group had less than 200 kcal per week (less than one hr per week).
The risk of cardiovascular disease events decreased with higher levels of physical activity. Compared to the reference group, relative risk reductions were associated with ¡_1,500, 600 to 1,499, 200 to 599 kcal/wk of 41 percent, 32 percent and 27 percent, respectively.
Exercise May Boost "Good" Cholesterol Levels
Regular exercise appears to modestly increase levels of high-density lipoprotein, or "good," cholesterol, according to a meta-analysis study in the May 28 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.__A low level of high-density lipoprotein cholesterol (HDL-C) is an independent risk factor for cardiovascular disease, the leading cause of death worldwide, according to background information in the article. There is strong evidence that individuals who are more physically active have higher HDL-C levels. "Thus, the value of regular aerobic exercise in increasing serum [blood] HDL-C level and in reducing the risk of cardiovascular disease has received widespread acceptance," the authors write. "In contrast, results of aerobic exercise studies vary considerably, depending on the exercise program (e.g., duration, intensity or frequency) and characteristics of subjects at baseline."__Satoru Kodama, M.D., of Ochanomizu University, Tokyo, and colleagues performed a meta-analysis of 25 articles reporting the results of randomized controlled trials that were published between 1966 and 2005 and assessed the effects of exercise on HDL-C. To be included in the analysis, the studies had to evaluate aerobic exercise in adults with an average age of 20 or older, specify HDL-C measurements at the beginning and end of the study, have a length of at least eight weeks, and randomly assign some participants to a group of exercisers and others to a control group of non-exercisers.__The 25 articles analyzed included a total of 1,404 participants with an average age range of 23 to 75 years and an average study period of 27.4 weeks. The exercise groups were told to exercise for an average of 3.7 sessions per week at an average of 40.5 minutes each, burning an average of 1,019 calories per week.__In all the studies combined, HDL-C increased by an average of 2.53 milligrams per deciliter in the exercise groups. The minimum amount of weekly exercise that appeared necessary to change HDL-C levels was 120 minutes or 900 calories burned. The effect of exercise was greater in those who had a higher total cholesterol level (220 milligrams per deciliter or greater) and in those with a body mass index of less than 28.__"In a previous observational study, every 1-milligram per deciliter increment in HDL-C level was reported to be associated with a 2 percent and 3 percent decreased risk of cardiovascular disease in men and women, respectively," the authors write. "If this observation were applied to our results, the increase in HDL-C level by exercise determined by this analysis would, by a rough estimate, result in a cardiovascular disease risk reduced by approximately 5.1 percent in men and 7.6 percent in women. This is potentially of substantial importance in public health, although the effect of reducing cardiovascular risk by increasing HDL-C level might be smaller than that by use of medications such as fibrates or niacin."__Only exercise duration, and not frequency or intensity, was associated with a change in HDL-C levels in the analysis. When the participants exercised for 23 to 74 minutes per session, each 10-minute increase in exercise duration corresponded to a 1.4-milligram per deciliter increase in HDL-C level. "This suggests that in improving blood HDL-C values, increasing time per session is better than performing multiple brief exercise sessions when total time for exercise is limited, as is the case for many people," the authors write.
Exercise stimulates the formation of new brain cells
Exercise has a similar effect to antidepressants on depression. This has been shown by previous research. Now Astrid Bjørnebekk at Karolinska Institutet has explained how this can happen: exercise stimulates the production of new brain cells.
In a series of scientific reports, she has searched for the underlying biological mechanisms that explain why exercise can be a form of therapy for depression and has also compared it with pharmacological treatment with an SSRI drug.
The experiment studies were conducted on rats. The results show that both exercise and antidepressants increase the formation of new cells in an area of the brain that is important to memory and learning. Astrid Bjørnebekk’s studies confirm previous research results, and she proposes a model to explain how exercise can have an antidepressant effect in mild to moderately severe depression. Her study also shows that exercise is a very good complement to medicines.
“What is interesting is that the effect of antidepressant therapy can be greatly strengthened by external environmental factors,” she says.
Previous studies have shown that drug abusers have lowered levels of the dopamine D2 receptor in the brain's reward system. It has been speculated that this may be of significance to the depressive symptoms drug abusers often suffer from. These rat studies show that genetic factors may influence how external environmental factors can regulate levels of the dopamine D2 receptor in the brain.
“Different individuals may have differing sensitivity to how stress lowers dopamine D2 receptor levels, for example. This might be significant in explaining why certain individuals develop depression more readily than others,” she says.
Even low levels of weekly exercise drive down blood pressure
Randomized controlled trial of home-based walking programs at and below current recommended levels of exercise in sedentary adults
Even low levels of weekly exercise drive down blood pressure and boost overall fitness, suggests a small study in the Journal of Epidemiology and Community Health.
To stave off ill health, adults are currently recommended to indulge in 30 minutes of moderately strenuous exercise on at least five days of the week.
But few people meet these recommendations, with lack of time cited as the most common reason for failing to do so.
The study authors invited 106 healthy but sedentary civil servants between the ages of 40 and 60 to take part in an exercise programme for 12 weeks.
Some 44 people were randomly assigned to 30 minutes of brisk walking on five days of the week.
A further 42 were given the same programme, but for three days of the week. And the remainder were not asked to change their current lifestyle.
Pedometers were used to help participants monitor their walking and every participant recorded how long they walked for.
Blood pressure, blood cholesterol, weight, hip and waist girth, and overall fitness (functional capacity) were all measured at the start and finish of the 12 week study.
Most people (89%) lasted the course.
There were no changes in any of the measures among the non-walkers. But systolic blood pressure and waist and hip girth fell significantly in both groups of walkers.
Overall fitness also increased in the walkers.
Falls of a few mm in blood pressure and shrinkage of a few centimetres in hip and waist circumference are enough to make a difference to an individual’s risk of dying from a cardiovascular disease, say the authors
Furthermore, the findings show that moderate intensity physical exercise below the recommended weekly levels still makes a difference to health, they add.
Fitness may reduce inflammation
A recent study by kinesiology and community health researchers at the University of Illinois provides new evidence that may help explain some of the underlying biological mechanisms that take place as the result of regular exercise. According to the researchers, that knowledge could potentially lead to a better understanding of the relationship between exercise and inflammation.
The objective of their research was to examine the independent effect of parasympathetic tone – in this case, determined by assessing heart-rate recovery after exercise – on circulating levels of C-reactive protein (CRP). Parasympathetic tone and its inverse function – sympathetic tone – are components of the autonomic nervous system. CRP, which is secreted by the liver, circulates in the bloodstream and is a biomarker for inflammation in the body.
“The sympathetic nervous system speeds things up, and the parasympathetic slows things down,” said Victoria J. Vieira, a predoctoral fellow in kinesiology and community health and in nutritional sciences, and the primary author and designer of the study, published in a recent issue of the Journal of the American Geriatrics Society. “So when you’re exercising, your sympathetic nervous system will be on, increasing your heart rate, your respiration, etc. Once you stop, your body always tries to get back to homeostasis. So the parasympathetic nervous system kicks in to get everything back down to baseline levels.”
Co-author and kinesiology and community health professor Jeffrey A. Woods said cardiologists are already routinely gauging CRP levels in much the same way they look at lipids panels to assess cholesterol levels.
“Certainly, that’s being done in the cardiovascular disease realm, but I think (it may be effectively used as a monitor) for other diseases, such as Alzheimer’s, diabetes and metabolic syndrome,” he said.
Woods said the main question motivating the current research was, “What factors are related to CRP in the elderly?”
“We’ve known that as people age, their CRP levels go up,” Vieira said. “That’s one of the reasons why older individuals are more prone to develop inflammation-related diseases such as diabetes and heart disease. So we just wanted to look at what’s predicting those levels of CRP in an average older population that is relatively healthy.”
Perhaps the most notable result of the study, according to the researchers, relates to heart-rate recovery following exercise.
“The quicker the individuals were able to get back to their resting heart rate after a strenuous exercise test was inversely related to their CRP,” Vieira said. “In other words, individuals who had better parasympathetic tone had lower levels of inflammation.
“And the reason we’re excited about this is that exercise is a great way to improve parasympathetic tone. When you exercise – that is the sympathetic/parasympathetic communication – your sympathetic goes up, and when you stop exercising, your parasympathetic kicks in to bring you back to normal. An untrained person will take a while to get their heart rate back down to resting. A trained person’s heart rate will come back down very quickly.”
The cross-sectional study focused on baseline test results from 132 sedentary, independently living individuals aged 60 to 83 (47 males; 85 females) who had been recruited to participate in the Immune Function Intervention Trial (ImFIT), a randomized longitudinal trial designed by Woods and funded by the National Institute on Aging to examine the relationship between exercise and immune function.
Participants included only individuals who did not take medications that included corticosteroids, which could interfere with immune measurements. Smokers and/or those with severe arthritis, a history of cancer or inflammatory disease, chronic obstructive pulmonary disorder, uncontrolled diabetes mellitus, congestive heart failure, recent illness or vaccination, or a positive stress test were excluded.
The physical fitness of subjects was assessed through a battery of tests that measured such variables as fatigue, blood pressure, oxygen intake and carbon dioxide elimination and heart-rate recovery in conjunction with exercise on a walking treadmill. Tests also were administered to determine the subjects’ levels of physical activity, physical fitness, emotional stress and body composition (bone density and body fat). Blood samples also were drawn to measure CRP levels.
“The major criterion we were looking at was their fitness level,” Vieira said. “A strength of our study is that we have very good data on their fitness levels.”
And while other studies have explored the relationship between exercise and inflammation, another unique aspect of the U. of I. research, Vieira said, is that “no other studies have adjusted for fitness and body fat percentages simultaneously to really get at that question, ‘Is exercise independently reducing CRP levels, or is it modulated through a decrease in adiposity (body fat)?’ ”
Because the study was cross-sectional – meaning the researchers essentially took a snapshot of the participants’ reactions and measurements at a single, fixed point only – Vieira said it was important to note that “we can’t say anything about cause and effect relationships.”
However, Woods said, “it gives you some idea of what factors are related, and then you test those in a more rigorous manner.”
Vieira said the research “certainly suggests that fitness may be associated with a decrease in inflammation even independent of body fat and several things, and the mechanism may involve a parasympathetic anti-inflammatory reflex.”
“We know inflammation is bad. We know it increases as we age, with stress and other things,” she said. “So if we can decrease that to protect ourselves somehow by just adopting a physically active lifestyle, that’s definitely an advantage.”
And while the study confirms the conclusions of previous research by others indicating that high body fat is related to high inflammation and high fitness to low inflammation, “the unique part of this paper is that controlling for those, we also show that high parasympathetic tone is related to low inflammation,” Woods said.
“And it’s even independent of their fitness level,” Vieira interjected.
“Fitness, fatness and parasympathetic tone appear to be important,” Woods said, summing up the findings. “And at least according to our results, parasympathetic tone might even be more important than those other factors.”
Exercise may play role in reducing inflammation in damaged skin tissue
In recent years, researchers at the University of Illinois have uncovered a host of reasons for people to remain physically active as they age, ranging from better brain function to improved immune responses.
Now a new U. of I. study points to yet another benefit: a link between moderate exercise and decreased inflammation of damaged skin tissue.
“The key point of the study is that moderate exercise sped up how fast wounds heal in old mice,” said researcher K. Todd Keylock, who noted that the improved healing response “may be the result of an exercise-induced anti-inflammatory response in the wound.”
Keylock, now a professor of kinesiology at Bowling Green State University, conducted the research as a doctoral student while working with Jeffrey A. Woods, a U. of I. professor of kinesiology and integrative immunology and behavior. The results appear in the current online edition of the American Journal of Physiology: Regulatory, Integrative and Comparative Physiology. In addition to Keylock and Woods, co-authors are Victoria Vieira, a predoctoral fellow in kinesiology and community health and in nutritional sciences; Matthew Wallig, a professor of veterinary pathobiology; Luisa A. DiPietro, a professor of periodontics and director of the Center for Wound Healing and Tissue Regeneration at the U. of I. at Chicago, and Megan Schrementi, a postdoctoral student in periodontics, U. of I. at Chicago.
While previous research conducted at Ohio State University demonstrated a correlation between wound healing response time and moderate exercise, that research did not reveal a physiological cause for the reaction.
“That’s the key part that our study adds – that the acceleration and healing were associated with decreased levels of inflammation,” Keylock said.
“One of the proposed mechanisms whereby aging adds to delayed healing is that the aged have hyper-inflammatory response to wounding,” Woods said. “The thought is that the exaggerated inflammatory response slows the healing process. So, in essence, what happened here is that the exercise reduced the exaggerated inflammatory response.”
Keylock explained that exercise may be contributing to that reduction in any number of ways.
“Increasing blood flow during the time of exercise is one (possibility),” he said. “We’ve shown in the past that has an effect on how certain immune cells – such as macrophages, function. “And if exercise can help decrease the amount of inflammatory cytokines put out by macrophages, maybe that would help decrease the inflammation, and therefore, speed healing.”
Cytokines are molecules that signal and direct immune cells, such as macrophages, to the site of an infection, Woods said. Macrophages play two critical roles in the wound-healing process, according to Keylock.
“First, they help fight any infection that may have gotten into the wound, and they also help the wound repair itself and get back to its original strength,” Keylock said.
Woods noted that if an exaggerated inflammatory response occurs when an older person incurs a wound, “the proinflammatory cytokines that the macropahges produce slow the rate of healing. And interestingly,” he said, “macrophages are drawn to damaged tissue and hypoxic tissue, that is, tissue that has low oxygen content. Wounds, because of the damage to the blood vessels, typically are hypoxic, and macrophages are attracted to that.
“So one potential thing that exercise might be doing, although we would need to test this, is reducing hypoxia within the wounds. And it’s known that hyperbaric oxygen therapy – which has been used with burn patients – speeds wound healing in some people.”
The next step required to better understand the mechanisms at work with respect to the exercise-healing relationship will be to test the researchers’ theories in people. Woods said he expects to begin such trials in the near future.
In the meantime, Keylock hopes to initiate similar tests as those done at the U. of I., but with diabetic mice, which also have delayed wound-healing responses and high levels of inflammation.
“The public-health message of this applies not just to older people, but also to diabetics, those who are obese and many different populations at risk of having high levels of inflammation,” he said. Those other populations include people with congestive heart failure and coronary heart disease.
“If exercise can help decrease inflammation, all of those populations would benefit.”
Woods speculates additional research may even eventually prove the health benefits of exercise among a much broader sector of individuals.
“This is going a bit beyond our results, but there are certain characteristics ... a set of events that are followed when any tissue is damaged – not just skin, like in this study, but arterial walls or other internal organs,” he said. “First, there’s hemostasis, which is limiting blood leakage. Then there’s an inflammatory process, then a regenerative process. So, using this model, we may be able to get at whether exercise could have farther-reaching implications for tissue damage in general.
“There are probably some things unique to the skin, as opposed to these other tissues, so we can’t make leaps of faith,” he cautioned. “But if we study the inflammatory process, the regenerative process in one tissue might have implications for other tissues.”
Meanwhile, the benefits of regular, moderate exercise – essentially a brisk walk most days of the week – for older adults, are many.
“There’s obviously the financial cost, which is important,” Keylock said, noting that “the clinical impact of delayed wound healing in the aged population is priced at more than $9 billion per year in the United States.”
“But the personal cost to people with poorly healing wounds is tremendous,” he said, “because it means not only pain and suffering, but also means they’re immobile or their mobility is limited for a period of time. So, faster healing wounds would mean getting them up on their feet again. For people with poorly healing wounds, like diabetics, that’s a critical factor.”
Woods added: “The bottom line is that if you are wounded or have a problem healing, exercise is safe and potentially beneficial.”
'Use it or lose it'
Research proves that maintaining physical activity in middle age leads to better basic physical abilities as we age, and that weight is not a deciding factor
Researchers from the Peninsula Medical School in Exeter, UK, have concluded a study that proves a direct link between levels of physical activity in middle age and physical ability later in life – regardless of body weight.
Dr. Iain Lang headed the research team from the Epidemiology and Public Health Group at the Peninsula Medical School. The team found that middle-aged people who maintained a reasonable level of physical activity were less likely to become unable to walk distances, climb stairs, maintain their sense of balance, stand from a seated position with their arms folded, or sustain their hand grip as they get older.
Research showed that, among men and women aged 50 to 69 years and across all weight ranges, the rate of decreased physical ability later in life was twice as high among those who were less physically active.
The research team studied 8,702 participants in the US Health and Retirement Study and 1,507 people taking part in the English Longitudinal Study of Ageing. Each subject was followed for up to six years.
Findings showed that being overweight or obese was associated with an overall increased risk of physical impairment but that, regardless of weight, people who engaged in heavy housework or gardening, who played sport or who had a physically active job, were more likely to remain mobile later in life.
Physical activity of about 30 minutes three or more times a week resulted in fewer than 13 per cent of people developing some sort of physical disability, while this rate increased to 24 per cent where subjects were less active.
Dr. Lang commented: “There are three truly interesting results from this research. The first is that our findings were similar from the US and the UK, which suggests that they are universal. The second is that exercise in middle age does not just benefit people in terms of weight loss – it also helps them to remain physically healthy and active later in life. The third is that, in terms of results from activity, weight does not seem to be an issue.”
Exercise = Less likely To Die
Michael F. Leitzmann, M.D., Dr.P.H., also of the National Cancer Institute, and colleagues analyzed the results of two questionnaires on physical activity from 252,925 of the participants (142,828 men and 110,097 women). Of those, 7,900 died during follow-up. Compared with being inactive, individuals who performed the amount of moderate physical activity recommended in national guidelines (at least 30 minutes most days of the week) were 27 percent less likely to die and those who achieved the goal for vigorous physical activity (at least 20 minutes three times per week) were 32 percent less likely to die. Smaller amounts of physical activity also appeared to be associated with a 19 percent reduced risk of death.
In Men, Exercise Benefits Prostate, Sexuality
Protection against heart disease, stroke, diabetes, obesity, hypertension, memory loss, colon cancer, fractures, and depression should be enough to get men exercising. But those who need extra motivation should consider the added benefits to their prostates and sexuality, reports the May 2007 issue of Harvard Men’s Health Watch.__A 2006 study from Sweden reported that regular exercise is associated with a reduced risk of moderate and severe symptoms of benign prostatic hyperplasia (BPH). After taking other risk factors into account, the most active men were 28% less likely to have substantial lower urinary tract symptoms than the least active men. The Harvard Men’s Health Watch notes that the effect of exercise on prostate cancer is less clear. Some studies suggest that exercise can reduce risk, while others do not.__Although erectile dysfunction is not life-threatening, it can surely impair quality of life. A Harvard study linked regular exercise to a 41% reduction in the risk of erectile dysfunction—all it took was about 30 minutes of walking a day. And in 2004, a randomized clinical trial reported that moderate exercise (averaging less than 28 minutes a day) can help restore sexual performance in obese, middle-aged men with erectile dysfunction.
Caffeine and exercise can team up to prevent skin cancer
A potential dynamic duo that may help avert sun-induced skin cancer
Regular exercise and little or no caffeine has become a popular lifestyle choice for many Americans. But a new Rutgers study has found that it may not be the best formula for preventing sun-induced skin damage that could lead to cancer. Low to moderate amounts of caffeine, in fact, along with exercise can be good for your health.
According to the National Cancer Institute, sunlight-induced skin cancer is the most prevalent cancer in the United States with more than 1 million new cases each year. A research team at Rutgers, The State University of New Jersey, showed that a combination of exercise and some caffeine protected against the destructive effects of the sun’s ultraviolet-B (UVB) radiation, known to induce skin cancer. The caffeine and exercise seemingly conspire in killing off precancerous cells whose DNA has been damaged by UVB-rays.
The studies, conducted in the Susan Lehman Cullman Laboratory for Cancer Research at Rutgers’ Ernest Mario School of Pharmacy, appear in the July 31 Proceedings of the National Academy of Sciences (PNAS).
Groups of hairless mice, whose exposed skin is vulnerable to the sun, were the test subjects in experiments in which one set drank caffeinated water (the human equivalent of one or two cups of coffee a day); another voluntarily exercised on a running wheel; while a third group both drank and ran. A fourth group, which served as a control, didn’t run and didn’t caffeinate. All of the mice were exposed to lamps that generated UVB radiation that damaged the DNA in their skin cells.
Some degree of programmed cell death, also known as apoptosis, was observed in the DNA-damaged cells of all four groups, but the caffeine drinkers and exercisers showed an increase over the UVB-treated control group. Apoptosis is a way in which cells with badly damaged DNA commit suicide – UVB-damaged cells in this case.
“If apoptosis takes place in a sun-damaged cell, its progress toward cancer will be aborted,” said Allan Conney, director of Rutgers’ Cullman Laboratory and one of the paper’s authors.
To determine the extent of programmed cell death among the four groups of UVB-treated mice, the Rutgers team looked at physical changes in the cells. The scientists also relied on chemical markers, such as caspase-3 – an enzyme that is involved in killing DNA-damaged cells – and p53, a tumor suppressor.
“The differences between the groups in the formation of UVB-induced apoptotic cells – those cells derailed from the track leading to skin cancer – were quite dramatic,” Conney said.
Compared to the UVB-exposed control animals, the caffeine drinkers showed an approximately 95 percent increase in UVB-induced apoptosis, the exercisers showed a 120 percent increase, while the mice that were both drinking and exercising showed a nearly 400 percent increase.
“The most dramatic and obvious difference between the groups came from the caffeine-drinking runners, a difference that can likely be attributed to some kind of synergy,” Conney said. The authors suggested several mechanisms at the biochemical level that might be responsible for the protective effects of caffeine and exercise, but acknowledged that what is happening synergistically is still somewhat of a mystery.
“We need to dig deeper into how the combination of caffeine and exercise is exerting its influence at the cellular and molecular levels, identifying the underlying mechanisms,” Conney said. “With an understanding of these mechanisms we can then take this to the next level, going beyond mice in the lab to human trials. With the stronger levels of UVB radiation evident today and an upward trend in the incidence of skin cancer among Americans, there is a premium on finding novel ways to protect our bodies from sun damage.”
Exercise May Lower Risk for Parkinson’s Disease
The risk of developing Parkinson’s disease may be reduced with moderate to vigorous exercise or other recreational activities, according to research that will be presented at the American Academy of Neurology’s 59th Annual Meeting in Boston, April 28 – May 5, 2007.__The study followed more than 143,000 people with an average age of 63 over 10 years. In that time, 413 people developed Parkinson’s disease. Researchers found that those with moderate to vigorous activity levels were 40 percent less likely to develop Parkinson’s disease than those with no or light activity levels. Those with moderate to vigorous activity were exercising an average of a half hour per day or more.__“This study does not prove that exercise caused the lowered risk of Parkinson’s disease – it’s possible that something else lowers the risk,” said the study’s lead author Evan L. Thacker, SM, from the Harvard School of Public Health in Boston, MA. “But considering all of the other benefits of exercise, it certainly doesn’t hurt to make sure you get some moderate or vigorous exercise several times a week.”__The researchers also looked at the participants’ activity level at age 40 and found that there was no significant relationship between the level of physical activity at age 40 and the risk of developing Parkinson’s disease.__“If exercise truly does provide some protection against Parkinson’s disease, the protection may be relatively short term,” Thacker said. “However, in a previous study with a similar prospective design activity in early adulthood was related to lower risk for Parkinson’s disease, so the jury’s still out on this one.”
Exercise reverses aging in human skeletal muscle
Buck Institute faculty leads study showing 'genetic fingerprint' becoming younger in healthy seniors who did resistance training__Not only does exercise make most people feel better and perform physical tasks better, it now appears that exercise – specifically, resistance training -- actually rejuvenates muscle tissue in healthy senior citizens.__A recent study, co-led by Buck Institute faculty member Simon Melov, PhD, and Mark Tarnopolsky, MD, PhD, of McMaster University Medical Center in Hamilton, Ontario, involved before and after analysis of gene expression profiles in tissue samples taken from 25 healthy older men and women who underwent six months of twice weekly resistance training, compared to a similar analysis of tissue samples taken from younger healthy men and women. The results of the study appear in the May 23 edition of the on-line, open access journal PLoS One.__The gene expression profiles involved age-specific mitochondrial function; mitochondria act as the "powerhouse" of cells. Multiple studies have suggested that mitochondrial dysfunction is involved in the loss of muscle mass and functional impairment commonly seen in older people. The study was the first to examine the gene expression profile, or the molecular "fingerprint", of aging in healthy disease-free humans.__Results showed that in the older adults, there was a decline in mitochondrial function with age. However, exercise resulted in a remarkable reversal of the genetic fingerprint back to levels similar to those seen in the younger adults. The study also measured muscle strength. Before exercise training, the older adults were 59% weaker than the younger adults, but after the training the strength of the older adults improved by about 50%, such that they were only 38% weaker than the young adults.__"We were very surprised by the results of the study," said Melov. "We expected to see gene expressions that stayed fairly steady in the older adults. The fact that their 'genetic fingerprints' so dramatically reversed course gives credence to the value of exercise, not only as a means of improving health, but of reversing the aging process itself, which is an additional incentive to exercise as you get older."__The study participants were recruited at McMaster University. The younger (20 to 35 with an average age of 26) and older (older than 65 with an average age of 70) adults were matched in terms of diet and exercise; none of them took medication or had diseases that can alter mitochondrial function. Tissue samples were taken from the thigh muscle. The six month resistance training was done on standard gym equipment. The twice-weekly sessions ran an hour in length and involved 30 contractions of each muscle group involved, similar to training sessions available at most fitness centers. The strength test was based on knee flexion.__The older participants, while generally active, had never participated in formal weight training said co-first author Tarnopolsky, who directs the Neuromuscular and Neurometabolic Clinic at McMaster University. In a four month follow up after the study was complete, he said most of the older adults were no longer doing formal exercise in a gym, but most were doing resistance exercises at home, lifting soup cans or using elastic bands. "They were still as strong, they still had the same muscle mass," said Tarnopolsky. "This shows that it's never too late to start exercising and that you don't have to spend your life pumping iron in a gym to reap benefits."__Future studies are being designed to determine if resistance training has any genetic impact on other types of human tissue, such as those that comprise organs; researchers also want to determine whether endurance training (running, cycling) impacts mitochondrial function and the aging process. The most recent study also points to particular gene expressions that could be used as starting points for chemical screenings that could lead to drug therapies that would modulate the aging process.__"The vast majority of aging studies are done in worms, fruit flies and mice; this study was done in humans," said Melov. "It's particularly rewarding to be able to scientifically validate something practical that people can do now to improve their health and the quality of their lives, as well as knowing that they are doing something which is actually reversing aspects of the aging process."
Exercise improves thinking, reduces diabetes risk in overweight children
Just three months of daily, vigorous physical activity in overweight children improves their thinking and reduces their diabetes risk, researchers say.
Studies of about 200 overweight, inactive children ages 7-11 also showed that a regular exercise program reduces body fat and improves bone density.
“Is exercise a magic wand that turns them into lean, healthy kids? No. They are still overweight but less so, with less fat, a healthier metabolism and an improved ability to handle life,” says Dr. Catherine Davis, clinical health psychologist at the Medical College of Georgia and lead investigator.
All study participants learned about healthy nutrition and the benefits of physical activity; one-third also exercised 20 minutes after school and another third exercised for 40 minutes. Children played hard, with running games, hula hoops and jump ropes, raising their heart rates to 79 percent of maximum, which is considered vigorous.
“Aerobic exercise training showed dose-response benefits on executive function (decision-making) and possibly math achievement, in overweight children,” researchers write in an abstract being presented during The Obesity Society’s Annual Scientific Meeting Oct. 20-24 in New Orleans. “Regular exercise may be a simple, important method of enhancing children’s cognitive and academic development. These results may persuade educators to implement vigorous physical activity curricula during a childhood obesity epidemic.”
Functional magnetic resonance imaging studies, which show the brain at work, were performed on a percentage of children in each group and found those who exercised had different patterns of brain activity during an executive function task.
“Look what good it does when they exercise,” says Dr. Davis. “This is an important public health issue we need to look at as a nation to help our children learn and keep them well.”
Unprecedented obesity and inactivity rates in America’s children are impacting health, including dramatic increases in the incidence of type 2 diabetes, a disease formerly known as adult-onset diabetes. Overweight children also have slightly lower school achievement, on average.
“We hope these findings will help persuade policymakers, schools and communities that time spent being physically active enhances, rather than detracts, from learning,” says Dr. Davis.
“There have been several studies that have shown that exercise produces kind of a selective effect, particularly with older adults, in cognitive tasks that require regulation of behaviors,” says Dr. Phillip D. Tomporowski, experimental psychologist at the University of Georgia and a key collaborator.
For this study, researchers gave the children tests that look at their decision-making processes. In the first such studies in children, the researchers found small to moderate improvements in children who exercised as well as a hint of increased math achievement.
“We have a number of studies conducted with animals that examined what influence physical activity has on blood flow, metabolic activity, brain function, glucose regulation, and they all demonstrate the same theme: that physical activity done on a regular basis has a protective effect,” says Dr. Tomporowski. “It doesn’t take too much to make the leap that it might influence developing children as well.”
Looking at the children’s insulin resistance, a precursor of type 2 diabetes in which it takes more insulin to convert glucose into energy, researchers found levels dropped 15 percent in the 20-minute exercise group and 21 percent in the 40-minute group. The control group stayed about the same.
“Increasing volume of regular aerobic exercise shows increased benefits on insulin resistance in overweight children, indicating reduced risk of type 2 diabetes, regardless of sex or race,” they write.
“We also know that if you stop exercising, you lose all the benefits,” adds Dr. Davis. “Exercise works if you do it.”
Adult studies have yielded comparable findings regarding exercise’s impact on insulin resistance and cognition.
The researchers tested oral glucose tolerance, measuring insulin response after children drank a small amount of glucose, before and after the studies. “Once your glucose levels start to rise, it’s called impaired glucose tolerance and that is a precursor of diabetes. It’s called pre-diabetes now,” says Dr. Davis, noting that overweight children typically have higher insulin resistance than their leaner peers. Insulin resistance is an early sign of diabetes risk that appears before glucose levels start to rise. Growth associated with puberty can temporarily increase insulin resistance, Dr. Davis notes, so because some of the children were beginning puberty, they made adjustments for the level of sex hormones.
DEXA scanning, which uses a small amount of radiation to quantify bone, tissue and fat, was used to accurately assess body composition. Executive function was measured using the Cognitive Assessment System and math skills using the Woodcock Johnson Test of Achievement III.
“If physical education were ideal, which it’s not – it’s not daily and it’s not active – then children could achieve this within the school day,” Dr. Davis says, pointing to benefits derived by children exercising just 20 minutes a day. “We are not there. To achieve maximum benefit, we were able to show it will take more than PE.”
Osteoporosis: Calcium and exercise to strengthen the bones – do you get enough?
Exercise strengthens the bones and might help reduce the risk of falling
Some people believe that they can best protect themselves by not moving around too much and trying to avoid situations where they might have a chance of falling. But in reality being too immobile is one of the major risk factors for osteoporosis. If you spend a large part of the day sitting or lying down, your bones are more likely to become weak and brittle. Physical activity that involves carrying your weight can actually strengthen your bones. One of the easier ways to get exercise with a low risk of injury is brisk walking. According to the Institute, even in older age, walking is a simple way of getting enough exercise that people feel comfortable with - and it benefits more than the bones, as well.
Professor Sawicki said: "Injury is of course always possible when you exercise. But people who are more active strengthen their muscles and bones - and that can help them stay physically stable and secure. People may gain more confidence in their bodies and that might mean a lower risk of stumbling and falling."
Can exercise prevent a severe stroke?
A new study shows that people who are physically active before suffering a stroke may have less severe problems as a result and recover better compared to those who did not exercise before having a stroke. The research is published in the October 21, 2008, print issue of Neurology®, the medical journal of the American Academy of Neurology.
The study found that the top 25 percent of people who exercised the most were two-and-a-half-times more likely to suffer a less severe stroke compared with people who were in the bottom quarter of the group. The most active also had a better chance of long-term recovery.
New MU Study Indicates that Exercise Prevents Fatty Liver Disease
Oct. 29, 2008
It’s easy to go to the gym on a regular basis right after a person buys the gym membership. It’s also easy to skip the gym one day, then the next day and the day after that. A new University of Missouri study indicates that the negative effects of skipping exercise can occur in a short period. The researchers found that a sudden transition to a sedentary lifestyle can quickly lead to symptoms of nonalcoholic fatty liver disease (hepatic steatosis), which affects at least 75 percent of obese people.
“We found that the cessation of daily exercise dramatically activates specific precursors known to promote hepatic steatosis,” said Jamal Ibdah, professor of medicine and medical pharmacology and physiology in the MU School of Medicine. “This study has important implications for obese humans who continually stop and start exercise programs. Our findings strongly suggest that a sudden transition to a sedentary lifestyle increases susceptibility to nonalcoholic fatty liver disease.”
Nonalcoholic fatty liver disease is a reversible condition that causes fat to accumulate in liver cells of obese people. As Westernized societies are experiencing a weight gain epidemic, the prevalence of the disease is growing, Ibdah said.
In the study, researchers gave obese rats access to voluntary running wheels for 16 weeks. Scientists then locked the wheels, and transitioned the animals to a sedentary condition. After 173 hours, or about seven days, the rats began showing signs of factors responsible for promoting hepatic steatosis. In the animals tested immediately at the end of 16 weeks of voluntary running, there were no signs of hepatic steatosis.
“Physical activity prevented fatty liver disease by 100 percent in an animal model of fatty liver disease,” said Frank Booth, a professor in the MU College of Veterinary Medicine and the MU School of Medicine and a research investigator in the Dalton Cardiovascular Research Center. “In contrast, 100 percent of the group that did not have physical activity had fatty liver disease. This is a remarkable event. It is rare in medicine for any treatment to prevent any disease by 100 percent.”
The study, “Cessation of Daily Exercise Dramatically Alters Precursors of Hepatic Steatosis in Otsuka Long-Evans Tokushima Fatty (OLETF) Rats,” was published in The Journal of Physiology.
Short bursts of high intensity sprints—known to benefit muscle and improve exercise performance—can improve the function and structure of blood vessels, in particular arteries that deliver blood to our muscles and heart, according to new research from McMaster University.
The study, lead by kinesiology doctoral student Mark Rakobowchuk, is published online in the journal American Journal of Physiology. Regulatory, Integrative & Comparative Physiology.
The findings support the idea that people can exercise using brief, high-intensity forms of exercise and reap the same benefits to cardiovascular health that can be derived from traditional, long-duration and moderately intense exercise.
"As we age, the arteries become stiffer and tend to lose their ability to dilate, and these effects contribute to high blood pressure and cardiovascular disease," says Maureen MacDonald, academic advisor and an associate professor in the Department of Kinesiology. "More detrimental is the effect that blood vessel stiffening has on the heart, which has to circulate blood".
The research compared individuals who completed interval training using 30-second "all-out" sprints three days a week to a group who completed between 40 and 60 minutes of moderate-intensity cycling five days a week.
It found that six weeks of intense sprint interval exercise training improves the structure and function of arteries as much as traditional and longer endurance exercise with larger time commitment.
"More and more, professional organizations are recommending interval training during rehabilitation from diseases like chronic obstructive pulmonary disease, peripheral artery disease and cardiovascular disease. Our research certainly provides evidence that this type of exercise training is as effective as traditional moderate intensity training," says MacDonald. "We wouldn't be surprised to see more rehabilitation programs adopt this method of training since it is often better tolerated in diseased populations".
Further, this research also shows that those who have a hard time scheduling exercise into their life can still benefit from the positive effects, if they are willing to work hard for brief periods of time, she says.
Daily exercise dramatically lowers men's death rates
American Heart Association rapid access journal report:
Increased exercise capacity reduces the risk of death in African-American and Caucasian men, researchers reported in Circulation: Journal of the American Heart Association.
The government-supported Veterans Affairs study included 15,660 participants and is the largest known to assess the link between fitness and mortality.
“It is important to emphasize that it takes relatively moderate levels of physical activity — like brisk walking — to attain the associated health benefits. Certainly, one does not need to be a marathon runner. This is the message that we need to convey to the public,” said Peter Kokkinos, Ph.D., lead author of the study and director of the Exercise Testing and Research Lab in the cardiology department at the Veterans Affairs Medical Center in Washington, D.C.
Professor Kokkinos and colleagues investigated exercise capacity as an independent predictor of overall mortality for African-American men (6,749) and Caucasian men (8,911) and also examined whether racial differences in exercise capacity influence the risk of death. Veterans were tested by a standardized treadmill test to assess exercise capacity between May 1983 and December 2006 at Veterans Affairs medical centers in Washington, D.C., and Palo Alto, Calif. The men were encouraged to exercise until fatigued unless they developed symptoms or other indicators of ischemia. These individuals were then followed for an average of 7.5 years and death rates were recorded.
Researchers classified the subjects into fitness categories based on their treadmill performance, expressed as peak metabolic equivalents (METs) achieved. Technically, a MET is equivalent to oxygen consumption of 3.5 milliliters per kilograms of body weight per minute. One MET represents the amount of oxygen the person uses at rest. Anything above one MET represents work. The higher the MET level achieved, the more fit the individual.
Based on this concept, the researchers divided the participants into four categories:
0. 3,170 men were “low fit,” achieving less than 5 METs;
0. 5,153 men were “moderately fit,” achieving 5 to 7 METs;
0. 5,075 were “highly fit,” achieving 7.1 to 10 METs; and
0. 2,261 were “very highly fit,” achieving more than 10 METs.
The study found that “highly fit” men had half the risk of death compared to “low fit” men. Men who achieved “very highly fit” levels had a 70 percent lower risk of death compared to those in the “low fit” category. For every 1-MET increase in exercise capacity (fitness), the risk for death from all causes was 13 percent for both African Americans and Caucasians.
Kokkinos said, “These findings are important for several reasons: First, we were able to quantify the health benefits per unit increase in exercise capacity. Second, this is the first study to provide information on physical activity and mortality in African Americans, information lacking until now. Keep in mind that death rates in African Americans are much higher when compared with Caucasians, in part because race and income negatively influence access to healthcare.”
“The Veterans Affairs’ health system is unique in that it ensures equal access to care regardless of a patient’s financial status,” he added. “Thus, it provides us with a unique opportunity to assess the impact of exercise or physical activity on death without the influence of healthcare differences.”
According to Kokkinos, most middle-age and older individuals can attain fitness levels with a brisk walk, 30 minutes per day, five to six days each week. “I do not advocate that everyone can start with 30 minutes of physical activity. In fact, 30 minutes may be too much for some people. If this is the case, split the routine into 10-15 minutes in the morning and another 10-15 minutes in the evening. The benefits will be similar if the exercise volume accumulated is similar,” he said.
“Our findings show that the risk of death is cut in half with an exercise capacity that can easily be achieved by a brisk walk of about 30 minutes per session 5-6 days per week,” he added. “Physicians should encourage individuals to initiate and maintain a physically active lifestyle, which is likely to improve fitness and lower the risk of death. Individuals should also discuss exercise with their physician before embarking on an exercise program.”
Moderate level of aerobic fitness may lower stroke risk
Abstract 119
A moderate level of aerobic fitness can significantly reduce stroke risk for men and women, according to a large, long-running study presented at the American Stroke Association’s International Stroke Conference 2008.
“Fitness has a protective effect regardless of the presence or absence of other stroke risk factors, including family history of cardiovascular disease, diabetes, high blood pressure, elevated cholesterol levels and high body mass index,” said Steven Hooker, Ph.D., the study’s lead author.
“This study is the first to suggest that there may be a significant independent association between cardiorespiratory fitness (CRF) and fatal and nonfatal stroke in men and nonfatal stroke in women,” said Hooker, director of the Prevention Research Center at the University of South Carolina Arnold School of Public Health, Columbia, S.C.
About 780,000 U.S. adults suffer a stroke each year, and stroke is a leading cause of serious, long-term disability in the United States, according to the American Stroke Association. It’s often fatal, claiming about 150,000 lives and ranking as the No. 3 cause of death. Researchers analyzed data on more than 60,000 people — 46,405 men and 15,282 women who participated in the Aerobics Center Longitudinal Study between 1970 and 2001 at the Cooper Aerobics Center in Dallas. The participants, ages 18 to 100 and free of known cardiovascular disease when they entered the study, were followed for an average of 18 years. During that time, 863 people — 692 men and 171 women — had strokes.
Upon entering the study, each participant took a test to measure CRF in which they walked on a treadmill at increasing grade and/or speed until they reached their maximal aerobic capacity.
Although many previous studies have looked at an association between self-reported physical activities and cardiovascular disease, few have used direct measurements such as the CRF measure used in this study, Hooker said. This is also the first study to explore the association between CRF and risk of stroke in women.
Men in the top quartile (25 percent) of CRF level had a 40 percent lower relative risk of stroke compared to men in the lowest quartile. That inverse relationship remained after adjusting for other factors such as smoking, alcohol intake, family history of cardiovascular disease, body mass index (an estimation of body fatness), high blood pressure, diabetes and high cholesterol levels, he said.
Among women, those in the higher CRF level had a 43 percent lower relative risk than those in the lowest fitness level.
The overall stroke risk dropped substantially at the moderate CRF level, with the protective effect persisting nearly unchanged through higher fitness levels. That corresponds to 30 minutes or more of brisk walking, or an equivalent aerobic activity, five days a week.
“We found that a low-to-moderate amount of aerobic fitness for men and women across the whole adult age spectrum would be enough to substantially reduce stroke risk,” Hooker said.
“Although stroke death rates have declined over the past few decades, the public health burden of stroke-related disabilities continues to be large and may even increase in coming years, as the population ages.”
Physical activity is a major modifiable cardiovascular disease risk factor. Increasing the nation’s CRF through regular physical activity could be a vital weapon to lower the incidence of stroke in men and women, he said.
One of the study’s limitations is that most of the participants were white, well-educated and middle-upper income, he said. He recommended that data be collected from other populations.
Walking Is Good
These days, it’s easy for people to get confused about exercise -- how many minutes a day should they spend working out, for how long and at what exertion level? Conflicting facts and opinions abound, but one Mayo Clinic physician says the bottom line is this: walking is good, whether the outcome measurement is blood pressure, diabetes, cardiovascular disease, joint problems or mental health.
“Getting out there and taking a walk is what it’s all about,” says James Levine, M.D., Ph.D., and a Mayo Clinic expert on obesity. “You don’t have to join a gym, you don’t have to check your pulse. You just have to switch off the TV, get off the sofa and go for a walk.”
The health benefit associated with walking is the subject of Dr. Levine’s editorial in the July issue of Mayo Clinic Proceedings. Dr. Levine’s piece is entitled, “Exercise: A Walk in the Park?” and accompanies a Proceedings article that showcases the merits of walking as beneficial exercise.
The study, undertaken by physicians from the Shinshu University Graduate School of Medicine in Matsumoto, Japan, determined that high-intensity interval walking may protect against high blood pressure and decreased muscle strength among older people.
Over five months, the Japanese researchers studied 246 adults who engaged in either no walking or moderate to high-intensity walking. The group who engaged in high-intensity walking experienced the most significant improvement in their health, the researchers found.
In his editorial, Dr. Levine says the study lends credence to the notion that walking is a legitimate, worthy mode of exercise for all people. Dr. Levine says it’s a welcome message for his patients, who fight obesity and appreciate that a walk is one way to improve their health.
Unlike a health club membership or personal trainer, walking “is there for everyone,” Dr. Levine says. “Walking doesn’t cost you anything, you can do it barefoot and you can do it now, this minute.”
“Sitting is bad for cholesterol, it’s bad for your back and muscles,” Dr. Levine says. “It’s such a terrible thing for our bodies to do and the less of it you do, the better. But activity is not easy. If it were easy, everyone would do it.”
A Walk a Day Might Help Keep the Doctor Away
New research reported in the Journal of the American Medical Association shows daily, mild exercise - walking or bike riding - improves the fitness of post-menopausal women who are currently sedentary, overweight or obese.__Timothy Church, M.D., Ph.D., of the Pennington Biomedical Research Center, led a team of researchers who examined the effect of various amounts of walking on more than 460 women. The results showed that as little as 15 minutes a day, five days a week of walking on a treadmill or riding a stationary bike improved fitness. __"The level of walking we studied was so light most people would not consider it exercise," Church said, "The message for women here is just get up and walk. You don't need a gym, you don't need fancy clothes or a stop-watch. All you need is a pair of comfortable shoes that you can walk in."__The women were randomly placed into one of four groups: a control group that did not exercise and groups that exercised 72 minutes, 135 minutes, or 191 minutes of exercise per week. Church's team found that the more exercise performed the greater the increase in fitness, which was expected. However, the lowest exercise groups also saw improvements in fitness, which the team did not expect. __"The surprising news," Church said, "is that the lowest exercise group showed significant improvement. We continue to recommend 30 minutes a day of walking at least five days a week, but the data suggests just doing something - even 15 minutes a day - is better than nothing.
Study explains how exercise lowers cardiovascular risk
It is well known that physical activity can improve cardiovascular health. But itis the impact exercise has on specific known risk factors that accounts for about 60 percent of that improvement, researchers reported in Circulation: Journal of the American Heart Association.
In a major study of over 27,000 women in the Womenis Health Study, researchers assessed a variety of risk factors and different levels of exercise in women who were followed for 11 years for new diagnosis of heart attack and stroke.
¡°Regular physical activity is enormously beneficial in preventing heart attack and stroke,¡± said Samia Mora, M.D., lead author of the study and instructor of medicine at Harvard Medical School in the divisions of preventive and cardiovascular medicine at Brigham and Womenis Hospital, Boston Mass. ¡°We found that even modest changes in risk factors for heart disease and stroke, especially those related to inflammation/hemostasis and blood pressure, can have a profound impact on preventing clinical events. This study is the first to examine the importance of a variety of known risk factors in explaining how physical activity prevents heart disease and stroke.¡±
The women ranged from 45 to 90 years old (average age 55) and were assessed for a full range of risk factors and different levels of exercise. There was a 40 percent reduction in heart attack and stroke between the highest and lowest exercise groups. The women self-reported physical activity, weight, height, hypertension and diabetes.
The long-term benefits of exercise start at a relatively low level, 600 kilocalories per week, equivalent to about two hours of physical activity per week, Mora said.
The study measured levels of a variety of traditional and novel risk factors to help understand the mechanisms that reduce risk for heart attack and stroke. Novel risk factors are emerging clinical, biochemical, and genetic markers that researchers have studied in order to better understand the development of a disease, to improve disease risk prediction, and to identify new targets for treatment.
Inflammatory and hemostatic biomarkers ¡ª fibrinogen, C-reactive protein and intracellular adhesion molecule-1 ¡ª together made the largest contribution to lower risk, 33 percent.
Blood pressure was the next major contributor to lower risk, 27 percent, followed by lipids, body mass index, glucose abnormalities, with minimal contribution from measures of renal function or homocysteine.
Inflammatory and hemostatic biomarkers are novel risk factors that relate to blood vessel function and inflammation of the arteries.
¡°Inflammatory and hemostatic factors as a group have overlapping functions and roles and, in our study, had the biggest effect in mediating exercise-related cardioprotection, more so than blood pressure or body weight,¡± Mora said. The study population was divided into four groups by levels of exercise:
• The highest level expended greater than or equal to 1,500 kilocalories per week (kcal/week) representing greater than five hours of moderately intense physical activity (such as brisk walking) per week.
• The next group expended from 600 to 1,499 kcal/week which reflected about two to five hours of physical activity per week.
• A third group represented an expenditure of 200 to 599 kcal/week, which is about one to two hours of physical activity per week.
• The reference group had less than 200 kcal per week (less than one hr per week).
The risk of cardiovascular disease events decreased with higher levels of physical activity. Compared to the reference group, relative risk reductions were associated with ¡_1,500, 600 to 1,499, 200 to 599 kcal/wk of 41 percent, 32 percent and 27 percent, respectively.
Exercise May Boost "Good" Cholesterol Levels
Regular exercise appears to modestly increase levels of high-density lipoprotein, or "good," cholesterol, according to a meta-analysis study in the May 28 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.__A low level of high-density lipoprotein cholesterol (HDL-C) is an independent risk factor for cardiovascular disease, the leading cause of death worldwide, according to background information in the article. There is strong evidence that individuals who are more physically active have higher HDL-C levels. "Thus, the value of regular aerobic exercise in increasing serum [blood] HDL-C level and in reducing the risk of cardiovascular disease has received widespread acceptance," the authors write. "In contrast, results of aerobic exercise studies vary considerably, depending on the exercise program (e.g., duration, intensity or frequency) and characteristics of subjects at baseline."__Satoru Kodama, M.D., of Ochanomizu University, Tokyo, and colleagues performed a meta-analysis of 25 articles reporting the results of randomized controlled trials that were published between 1966 and 2005 and assessed the effects of exercise on HDL-C. To be included in the analysis, the studies had to evaluate aerobic exercise in adults with an average age of 20 or older, specify HDL-C measurements at the beginning and end of the study, have a length of at least eight weeks, and randomly assign some participants to a group of exercisers and others to a control group of non-exercisers.__The 25 articles analyzed included a total of 1,404 participants with an average age range of 23 to 75 years and an average study period of 27.4 weeks. The exercise groups were told to exercise for an average of 3.7 sessions per week at an average of 40.5 minutes each, burning an average of 1,019 calories per week.__In all the studies combined, HDL-C increased by an average of 2.53 milligrams per deciliter in the exercise groups. The minimum amount of weekly exercise that appeared necessary to change HDL-C levels was 120 minutes or 900 calories burned. The effect of exercise was greater in those who had a higher total cholesterol level (220 milligrams per deciliter or greater) and in those with a body mass index of less than 28.__"In a previous observational study, every 1-milligram per deciliter increment in HDL-C level was reported to be associated with a 2 percent and 3 percent decreased risk of cardiovascular disease in men and women, respectively," the authors write. "If this observation were applied to our results, the increase in HDL-C level by exercise determined by this analysis would, by a rough estimate, result in a cardiovascular disease risk reduced by approximately 5.1 percent in men and 7.6 percent in women. This is potentially of substantial importance in public health, although the effect of reducing cardiovascular risk by increasing HDL-C level might be smaller than that by use of medications such as fibrates or niacin."__Only exercise duration, and not frequency or intensity, was associated with a change in HDL-C levels in the analysis. When the participants exercised for 23 to 74 minutes per session, each 10-minute increase in exercise duration corresponded to a 1.4-milligram per deciliter increase in HDL-C level. "This suggests that in improving blood HDL-C values, increasing time per session is better than performing multiple brief exercise sessions when total time for exercise is limited, as is the case for many people," the authors write.
Exercise stimulates the formation of new brain cells
Exercise has a similar effect to antidepressants on depression. This has been shown by previous research. Now Astrid Bjørnebekk at Karolinska Institutet has explained how this can happen: exercise stimulates the production of new brain cells.
In a series of scientific reports, she has searched for the underlying biological mechanisms that explain why exercise can be a form of therapy for depression and has also compared it with pharmacological treatment with an SSRI drug.
The experiment studies were conducted on rats. The results show that both exercise and antidepressants increase the formation of new cells in an area of the brain that is important to memory and learning. Astrid Bjørnebekk’s studies confirm previous research results, and she proposes a model to explain how exercise can have an antidepressant effect in mild to moderately severe depression. Her study also shows that exercise is a very good complement to medicines.
“What is interesting is that the effect of antidepressant therapy can be greatly strengthened by external environmental factors,” she says.
Previous studies have shown that drug abusers have lowered levels of the dopamine D2 receptor in the brain's reward system. It has been speculated that this may be of significance to the depressive symptoms drug abusers often suffer from. These rat studies show that genetic factors may influence how external environmental factors can regulate levels of the dopamine D2 receptor in the brain.
“Different individuals may have differing sensitivity to how stress lowers dopamine D2 receptor levels, for example. This might be significant in explaining why certain individuals develop depression more readily than others,” she says.
Even low levels of weekly exercise drive down blood pressure
Randomized controlled trial of home-based walking programs at and below current recommended levels of exercise in sedentary adults
Even low levels of weekly exercise drive down blood pressure and boost overall fitness, suggests a small study in the Journal of Epidemiology and Community Health.
To stave off ill health, adults are currently recommended to indulge in 30 minutes of moderately strenuous exercise on at least five days of the week.
But few people meet these recommendations, with lack of time cited as the most common reason for failing to do so.
The study authors invited 106 healthy but sedentary civil servants between the ages of 40 and 60 to take part in an exercise programme for 12 weeks.
Some 44 people were randomly assigned to 30 minutes of brisk walking on five days of the week.
A further 42 were given the same programme, but for three days of the week. And the remainder were not asked to change their current lifestyle.
Pedometers were used to help participants monitor their walking and every participant recorded how long they walked for.
Blood pressure, blood cholesterol, weight, hip and waist girth, and overall fitness (functional capacity) were all measured at the start and finish of the 12 week study.
Most people (89%) lasted the course.
There were no changes in any of the measures among the non-walkers. But systolic blood pressure and waist and hip girth fell significantly in both groups of walkers.
Overall fitness also increased in the walkers.
Falls of a few mm in blood pressure and shrinkage of a few centimetres in hip and waist circumference are enough to make a difference to an individual’s risk of dying from a cardiovascular disease, say the authors
Furthermore, the findings show that moderate intensity physical exercise below the recommended weekly levels still makes a difference to health, they add.
Fitness may reduce inflammation
A recent study by kinesiology and community health researchers at the University of Illinois provides new evidence that may help explain some of the underlying biological mechanisms that take place as the result of regular exercise. According to the researchers, that knowledge could potentially lead to a better understanding of the relationship between exercise and inflammation.
The objective of their research was to examine the independent effect of parasympathetic tone – in this case, determined by assessing heart-rate recovery after exercise – on circulating levels of C-reactive protein (CRP). Parasympathetic tone and its inverse function – sympathetic tone – are components of the autonomic nervous system. CRP, which is secreted by the liver, circulates in the bloodstream and is a biomarker for inflammation in the body.
“The sympathetic nervous system speeds things up, and the parasympathetic slows things down,” said Victoria J. Vieira, a predoctoral fellow in kinesiology and community health and in nutritional sciences, and the primary author and designer of the study, published in a recent issue of the Journal of the American Geriatrics Society. “So when you’re exercising, your sympathetic nervous system will be on, increasing your heart rate, your respiration, etc. Once you stop, your body always tries to get back to homeostasis. So the parasympathetic nervous system kicks in to get everything back down to baseline levels.”
Co-author and kinesiology and community health professor Jeffrey A. Woods said cardiologists are already routinely gauging CRP levels in much the same way they look at lipids panels to assess cholesterol levels.
“Certainly, that’s being done in the cardiovascular disease realm, but I think (it may be effectively used as a monitor) for other diseases, such as Alzheimer’s, diabetes and metabolic syndrome,” he said.
Woods said the main question motivating the current research was, “What factors are related to CRP in the elderly?”
“We’ve known that as people age, their CRP levels go up,” Vieira said. “That’s one of the reasons why older individuals are more prone to develop inflammation-related diseases such as diabetes and heart disease. So we just wanted to look at what’s predicting those levels of CRP in an average older population that is relatively healthy.”
Perhaps the most notable result of the study, according to the researchers, relates to heart-rate recovery following exercise.
“The quicker the individuals were able to get back to their resting heart rate after a strenuous exercise test was inversely related to their CRP,” Vieira said. “In other words, individuals who had better parasympathetic tone had lower levels of inflammation.
“And the reason we’re excited about this is that exercise is a great way to improve parasympathetic tone. When you exercise – that is the sympathetic/parasympathetic communication – your sympathetic goes up, and when you stop exercising, your parasympathetic kicks in to bring you back to normal. An untrained person will take a while to get their heart rate back down to resting. A trained person’s heart rate will come back down very quickly.”
The cross-sectional study focused on baseline test results from 132 sedentary, independently living individuals aged 60 to 83 (47 males; 85 females) who had been recruited to participate in the Immune Function Intervention Trial (ImFIT), a randomized longitudinal trial designed by Woods and funded by the National Institute on Aging to examine the relationship between exercise and immune function.
Participants included only individuals who did not take medications that included corticosteroids, which could interfere with immune measurements. Smokers and/or those with severe arthritis, a history of cancer or inflammatory disease, chronic obstructive pulmonary disorder, uncontrolled diabetes mellitus, congestive heart failure, recent illness or vaccination, or a positive stress test were excluded.
The physical fitness of subjects was assessed through a battery of tests that measured such variables as fatigue, blood pressure, oxygen intake and carbon dioxide elimination and heart-rate recovery in conjunction with exercise on a walking treadmill. Tests also were administered to determine the subjects’ levels of physical activity, physical fitness, emotional stress and body composition (bone density and body fat). Blood samples also were drawn to measure CRP levels.
“The major criterion we were looking at was their fitness level,” Vieira said. “A strength of our study is that we have very good data on their fitness levels.”
And while other studies have explored the relationship between exercise and inflammation, another unique aspect of the U. of I. research, Vieira said, is that “no other studies have adjusted for fitness and body fat percentages simultaneously to really get at that question, ‘Is exercise independently reducing CRP levels, or is it modulated through a decrease in adiposity (body fat)?’ ”
Because the study was cross-sectional – meaning the researchers essentially took a snapshot of the participants’ reactions and measurements at a single, fixed point only – Vieira said it was important to note that “we can’t say anything about cause and effect relationships.”
However, Woods said, “it gives you some idea of what factors are related, and then you test those in a more rigorous manner.”
Vieira said the research “certainly suggests that fitness may be associated with a decrease in inflammation even independent of body fat and several things, and the mechanism may involve a parasympathetic anti-inflammatory reflex.”
“We know inflammation is bad. We know it increases as we age, with stress and other things,” she said. “So if we can decrease that to protect ourselves somehow by just adopting a physically active lifestyle, that’s definitely an advantage.”
And while the study confirms the conclusions of previous research by others indicating that high body fat is related to high inflammation and high fitness to low inflammation, “the unique part of this paper is that controlling for those, we also show that high parasympathetic tone is related to low inflammation,” Woods said.
“And it’s even independent of their fitness level,” Vieira interjected.
“Fitness, fatness and parasympathetic tone appear to be important,” Woods said, summing up the findings. “And at least according to our results, parasympathetic tone might even be more important than those other factors.”
Exercise may play role in reducing inflammation in damaged skin tissue
In recent years, researchers at the University of Illinois have uncovered a host of reasons for people to remain physically active as they age, ranging from better brain function to improved immune responses.
Now a new U. of I. study points to yet another benefit: a link between moderate exercise and decreased inflammation of damaged skin tissue.
“The key point of the study is that moderate exercise sped up how fast wounds heal in old mice,” said researcher K. Todd Keylock, who noted that the improved healing response “may be the result of an exercise-induced anti-inflammatory response in the wound.”
Keylock, now a professor of kinesiology at Bowling Green State University, conducted the research as a doctoral student while working with Jeffrey A. Woods, a U. of I. professor of kinesiology and integrative immunology and behavior. The results appear in the current online edition of the American Journal of Physiology: Regulatory, Integrative and Comparative Physiology. In addition to Keylock and Woods, co-authors are Victoria Vieira, a predoctoral fellow in kinesiology and community health and in nutritional sciences; Matthew Wallig, a professor of veterinary pathobiology; Luisa A. DiPietro, a professor of periodontics and director of the Center for Wound Healing and Tissue Regeneration at the U. of I. at Chicago, and Megan Schrementi, a postdoctoral student in periodontics, U. of I. at Chicago.
While previous research conducted at Ohio State University demonstrated a correlation between wound healing response time and moderate exercise, that research did not reveal a physiological cause for the reaction.
“That’s the key part that our study adds – that the acceleration and healing were associated with decreased levels of inflammation,” Keylock said.
“One of the proposed mechanisms whereby aging adds to delayed healing is that the aged have hyper-inflammatory response to wounding,” Woods said. “The thought is that the exaggerated inflammatory response slows the healing process. So, in essence, what happened here is that the exercise reduced the exaggerated inflammatory response.”
Keylock explained that exercise may be contributing to that reduction in any number of ways.
“Increasing blood flow during the time of exercise is one (possibility),” he said. “We’ve shown in the past that has an effect on how certain immune cells – such as macrophages, function. “And if exercise can help decrease the amount of inflammatory cytokines put out by macrophages, maybe that would help decrease the inflammation, and therefore, speed healing.”
Cytokines are molecules that signal and direct immune cells, such as macrophages, to the site of an infection, Woods said. Macrophages play two critical roles in the wound-healing process, according to Keylock.
“First, they help fight any infection that may have gotten into the wound, and they also help the wound repair itself and get back to its original strength,” Keylock said.
Woods noted that if an exaggerated inflammatory response occurs when an older person incurs a wound, “the proinflammatory cytokines that the macropahges produce slow the rate of healing. And interestingly,” he said, “macrophages are drawn to damaged tissue and hypoxic tissue, that is, tissue that has low oxygen content. Wounds, because of the damage to the blood vessels, typically are hypoxic, and macrophages are attracted to that.
“So one potential thing that exercise might be doing, although we would need to test this, is reducing hypoxia within the wounds. And it’s known that hyperbaric oxygen therapy – which has been used with burn patients – speeds wound healing in some people.”
The next step required to better understand the mechanisms at work with respect to the exercise-healing relationship will be to test the researchers’ theories in people. Woods said he expects to begin such trials in the near future.
In the meantime, Keylock hopes to initiate similar tests as those done at the U. of I., but with diabetic mice, which also have delayed wound-healing responses and high levels of inflammation.
“The public-health message of this applies not just to older people, but also to diabetics, those who are obese and many different populations at risk of having high levels of inflammation,” he said. Those other populations include people with congestive heart failure and coronary heart disease.
“If exercise can help decrease inflammation, all of those populations would benefit.”
Woods speculates additional research may even eventually prove the health benefits of exercise among a much broader sector of individuals.
“This is going a bit beyond our results, but there are certain characteristics ... a set of events that are followed when any tissue is damaged – not just skin, like in this study, but arterial walls or other internal organs,” he said. “First, there’s hemostasis, which is limiting blood leakage. Then there’s an inflammatory process, then a regenerative process. So, using this model, we may be able to get at whether exercise could have farther-reaching implications for tissue damage in general.
“There are probably some things unique to the skin, as opposed to these other tissues, so we can’t make leaps of faith,” he cautioned. “But if we study the inflammatory process, the regenerative process in one tissue might have implications for other tissues.”
Meanwhile, the benefits of regular, moderate exercise – essentially a brisk walk most days of the week – for older adults, are many.
“There’s obviously the financial cost, which is important,” Keylock said, noting that “the clinical impact of delayed wound healing in the aged population is priced at more than $9 billion per year in the United States.”
“But the personal cost to people with poorly healing wounds is tremendous,” he said, “because it means not only pain and suffering, but also means they’re immobile or their mobility is limited for a period of time. So, faster healing wounds would mean getting them up on their feet again. For people with poorly healing wounds, like diabetics, that’s a critical factor.”
Woods added: “The bottom line is that if you are wounded or have a problem healing, exercise is safe and potentially beneficial.”
'Use it or lose it'
Research proves that maintaining physical activity in middle age leads to better basic physical abilities as we age, and that weight is not a deciding factor
Researchers from the Peninsula Medical School in Exeter, UK, have concluded a study that proves a direct link between levels of physical activity in middle age and physical ability later in life – regardless of body weight.
Dr. Iain Lang headed the research team from the Epidemiology and Public Health Group at the Peninsula Medical School. The team found that middle-aged people who maintained a reasonable level of physical activity were less likely to become unable to walk distances, climb stairs, maintain their sense of balance, stand from a seated position with their arms folded, or sustain their hand grip as they get older.
Research showed that, among men and women aged 50 to 69 years and across all weight ranges, the rate of decreased physical ability later in life was twice as high among those who were less physically active.
The research team studied 8,702 participants in the US Health and Retirement Study and 1,507 people taking part in the English Longitudinal Study of Ageing. Each subject was followed for up to six years.
Findings showed that being overweight or obese was associated with an overall increased risk of physical impairment but that, regardless of weight, people who engaged in heavy housework or gardening, who played sport or who had a physically active job, were more likely to remain mobile later in life.
Physical activity of about 30 minutes three or more times a week resulted in fewer than 13 per cent of people developing some sort of physical disability, while this rate increased to 24 per cent where subjects were less active.
Dr. Lang commented: “There are three truly interesting results from this research. The first is that our findings were similar from the US and the UK, which suggests that they are universal. The second is that exercise in middle age does not just benefit people in terms of weight loss – it also helps them to remain physically healthy and active later in life. The third is that, in terms of results from activity, weight does not seem to be an issue.”
Exercise = Less likely To Die
Michael F. Leitzmann, M.D., Dr.P.H., also of the National Cancer Institute, and colleagues analyzed the results of two questionnaires on physical activity from 252,925 of the participants (142,828 men and 110,097 women). Of those, 7,900 died during follow-up. Compared with being inactive, individuals who performed the amount of moderate physical activity recommended in national guidelines (at least 30 minutes most days of the week) were 27 percent less likely to die and those who achieved the goal for vigorous physical activity (at least 20 minutes three times per week) were 32 percent less likely to die. Smaller amounts of physical activity also appeared to be associated with a 19 percent reduced risk of death.
In Men, Exercise Benefits Prostate, Sexuality
Protection against heart disease, stroke, diabetes, obesity, hypertension, memory loss, colon cancer, fractures, and depression should be enough to get men exercising. But those who need extra motivation should consider the added benefits to their prostates and sexuality, reports the May 2007 issue of Harvard Men’s Health Watch.__A 2006 study from Sweden reported that regular exercise is associated with a reduced risk of moderate and severe symptoms of benign prostatic hyperplasia (BPH). After taking other risk factors into account, the most active men were 28% less likely to have substantial lower urinary tract symptoms than the least active men. The Harvard Men’s Health Watch notes that the effect of exercise on prostate cancer is less clear. Some studies suggest that exercise can reduce risk, while others do not.__Although erectile dysfunction is not life-threatening, it can surely impair quality of life. A Harvard study linked regular exercise to a 41% reduction in the risk of erectile dysfunction—all it took was about 30 minutes of walking a day. And in 2004, a randomized clinical trial reported that moderate exercise (averaging less than 28 minutes a day) can help restore sexual performance in obese, middle-aged men with erectile dysfunction.
Caffeine and exercise can team up to prevent skin cancer
A potential dynamic duo that may help avert sun-induced skin cancer
Regular exercise and little or no caffeine has become a popular lifestyle choice for many Americans. But a new Rutgers study has found that it may not be the best formula for preventing sun-induced skin damage that could lead to cancer. Low to moderate amounts of caffeine, in fact, along with exercise can be good for your health.
According to the National Cancer Institute, sunlight-induced skin cancer is the most prevalent cancer in the United States with more than 1 million new cases each year. A research team at Rutgers, The State University of New Jersey, showed that a combination of exercise and some caffeine protected against the destructive effects of the sun’s ultraviolet-B (UVB) radiation, known to induce skin cancer. The caffeine and exercise seemingly conspire in killing off precancerous cells whose DNA has been damaged by UVB-rays.
The studies, conducted in the Susan Lehman Cullman Laboratory for Cancer Research at Rutgers’ Ernest Mario School of Pharmacy, appear in the July 31 Proceedings of the National Academy of Sciences (PNAS).
Groups of hairless mice, whose exposed skin is vulnerable to the sun, were the test subjects in experiments in which one set drank caffeinated water (the human equivalent of one or two cups of coffee a day); another voluntarily exercised on a running wheel; while a third group both drank and ran. A fourth group, which served as a control, didn’t run and didn’t caffeinate. All of the mice were exposed to lamps that generated UVB radiation that damaged the DNA in their skin cells.
Some degree of programmed cell death, also known as apoptosis, was observed in the DNA-damaged cells of all four groups, but the caffeine drinkers and exercisers showed an increase over the UVB-treated control group. Apoptosis is a way in which cells with badly damaged DNA commit suicide – UVB-damaged cells in this case.
“If apoptosis takes place in a sun-damaged cell, its progress toward cancer will be aborted,” said Allan Conney, director of Rutgers’ Cullman Laboratory and one of the paper’s authors.
To determine the extent of programmed cell death among the four groups of UVB-treated mice, the Rutgers team looked at physical changes in the cells. The scientists also relied on chemical markers, such as caspase-3 – an enzyme that is involved in killing DNA-damaged cells – and p53, a tumor suppressor.
“The differences between the groups in the formation of UVB-induced apoptotic cells – those cells derailed from the track leading to skin cancer – were quite dramatic,” Conney said.
Compared to the UVB-exposed control animals, the caffeine drinkers showed an approximately 95 percent increase in UVB-induced apoptosis, the exercisers showed a 120 percent increase, while the mice that were both drinking and exercising showed a nearly 400 percent increase.
“The most dramatic and obvious difference between the groups came from the caffeine-drinking runners, a difference that can likely be attributed to some kind of synergy,” Conney said. The authors suggested several mechanisms at the biochemical level that might be responsible for the protective effects of caffeine and exercise, but acknowledged that what is happening synergistically is still somewhat of a mystery.
“We need to dig deeper into how the combination of caffeine and exercise is exerting its influence at the cellular and molecular levels, identifying the underlying mechanisms,” Conney said. “With an understanding of these mechanisms we can then take this to the next level, going beyond mice in the lab to human trials. With the stronger levels of UVB radiation evident today and an upward trend in the incidence of skin cancer among Americans, there is a premium on finding novel ways to protect our bodies from sun damage.”
Exercise May Lower Risk for Parkinson’s Disease
The risk of developing Parkinson’s disease may be reduced with moderate to vigorous exercise or other recreational activities, according to research that will be presented at the American Academy of Neurology’s 59th Annual Meeting in Boston, April 28 – May 5, 2007.__The study followed more than 143,000 people with an average age of 63 over 10 years. In that time, 413 people developed Parkinson’s disease. Researchers found that those with moderate to vigorous activity levels were 40 percent less likely to develop Parkinson’s disease than those with no or light activity levels. Those with moderate to vigorous activity were exercising an average of a half hour per day or more.__“This study does not prove that exercise caused the lowered risk of Parkinson’s disease – it’s possible that something else lowers the risk,” said the study’s lead author Evan L. Thacker, SM, from the Harvard School of Public Health in Boston, MA. “But considering all of the other benefits of exercise, it certainly doesn’t hurt to make sure you get some moderate or vigorous exercise several times a week.”__The researchers also looked at the participants’ activity level at age 40 and found that there was no significant relationship between the level of physical activity at age 40 and the risk of developing Parkinson’s disease.__“If exercise truly does provide some protection against Parkinson’s disease, the protection may be relatively short term,” Thacker said. “However, in a previous study with a similar prospective design activity in early adulthood was related to lower risk for Parkinson’s disease, so the jury’s still out on this one.”
Exercise reverses aging in human skeletal muscle
Buck Institute faculty leads study showing 'genetic fingerprint' becoming younger in healthy seniors who did resistance training__Not only does exercise make most people feel better and perform physical tasks better, it now appears that exercise – specifically, resistance training -- actually rejuvenates muscle tissue in healthy senior citizens.__A recent study, co-led by Buck Institute faculty member Simon Melov, PhD, and Mark Tarnopolsky, MD, PhD, of McMaster University Medical Center in Hamilton, Ontario, involved before and after analysis of gene expression profiles in tissue samples taken from 25 healthy older men and women who underwent six months of twice weekly resistance training, compared to a similar analysis of tissue samples taken from younger healthy men and women. The results of the study appear in the May 23 edition of the on-line, open access journal PLoS One.__The gene expression profiles involved age-specific mitochondrial function; mitochondria act as the "powerhouse" of cells. Multiple studies have suggested that mitochondrial dysfunction is involved in the loss of muscle mass and functional impairment commonly seen in older people. The study was the first to examine the gene expression profile, or the molecular "fingerprint", of aging in healthy disease-free humans.__Results showed that in the older adults, there was a decline in mitochondrial function with age. However, exercise resulted in a remarkable reversal of the genetic fingerprint back to levels similar to those seen in the younger adults. The study also measured muscle strength. Before exercise training, the older adults were 59% weaker than the younger adults, but after the training the strength of the older adults improved by about 50%, such that they were only 38% weaker than the young adults.__"We were very surprised by the results of the study," said Melov. "We expected to see gene expressions that stayed fairly steady in the older adults. The fact that their 'genetic fingerprints' so dramatically reversed course gives credence to the value of exercise, not only as a means of improving health, but of reversing the aging process itself, which is an additional incentive to exercise as you get older."__The study participants were recruited at McMaster University. The younger (20 to 35 with an average age of 26) and older (older than 65 with an average age of 70) adults were matched in terms of diet and exercise; none of them took medication or had diseases that can alter mitochondrial function. Tissue samples were taken from the thigh muscle. The six month resistance training was done on standard gym equipment. The twice-weekly sessions ran an hour in length and involved 30 contractions of each muscle group involved, similar to training sessions available at most fitness centers. The strength test was based on knee flexion.__The older participants, while generally active, had never participated in formal weight training said co-first author Tarnopolsky, who directs the Neuromuscular and Neurometabolic Clinic at McMaster University. In a four month follow up after the study was complete, he said most of the older adults were no longer doing formal exercise in a gym, but most were doing resistance exercises at home, lifting soup cans or using elastic bands. "They were still as strong, they still had the same muscle mass," said Tarnopolsky. "This shows that it's never too late to start exercising and that you don't have to spend your life pumping iron in a gym to reap benefits."__Future studies are being designed to determine if resistance training has any genetic impact on other types of human tissue, such as those that comprise organs; researchers also want to determine whether endurance training (running, cycling) impacts mitochondrial function and the aging process. The most recent study also points to particular gene expressions that could be used as starting points for chemical screenings that could lead to drug therapies that would modulate the aging process.__"The vast majority of aging studies are done in worms, fruit flies and mice; this study was done in humans," said Melov. "It's particularly rewarding to be able to scientifically validate something practical that people can do now to improve their health and the quality of their lives, as well as knowing that they are doing something which is actually reversing aspects of the aging process."
Exercise improves thinking, reduces diabetes risk in overweight children
Just three months of daily, vigorous physical activity in overweight children improves their thinking and reduces their diabetes risk, researchers say.
Studies of about 200 overweight, inactive children ages 7-11 also showed that a regular exercise program reduces body fat and improves bone density.
“Is exercise a magic wand that turns them into lean, healthy kids? No. They are still overweight but less so, with less fat, a healthier metabolism and an improved ability to handle life,” says Dr. Catherine Davis, clinical health psychologist at the Medical College of Georgia and lead investigator.
All study participants learned about healthy nutrition and the benefits of physical activity; one-third also exercised 20 minutes after school and another third exercised for 40 minutes. Children played hard, with running games, hula hoops and jump ropes, raising their heart rates to 79 percent of maximum, which is considered vigorous.
“Aerobic exercise training showed dose-response benefits on executive function (decision-making) and possibly math achievement, in overweight children,” researchers write in an abstract being presented during The Obesity Society’s Annual Scientific Meeting Oct. 20-24 in New Orleans. “Regular exercise may be a simple, important method of enhancing children’s cognitive and academic development. These results may persuade educators to implement vigorous physical activity curricula during a childhood obesity epidemic.”
Functional magnetic resonance imaging studies, which show the brain at work, were performed on a percentage of children in each group and found those who exercised had different patterns of brain activity during an executive function task.
“Look what good it does when they exercise,” says Dr. Davis. “This is an important public health issue we need to look at as a nation to help our children learn and keep them well.”
Unprecedented obesity and inactivity rates in America’s children are impacting health, including dramatic increases in the incidence of type 2 diabetes, a disease formerly known as adult-onset diabetes. Overweight children also have slightly lower school achievement, on average.
“We hope these findings will help persuade policymakers, schools and communities that time spent being physically active enhances, rather than detracts, from learning,” says Dr. Davis.
“There have been several studies that have shown that exercise produces kind of a selective effect, particularly with older adults, in cognitive tasks that require regulation of behaviors,” says Dr. Phillip D. Tomporowski, experimental psychologist at the University of Georgia and a key collaborator.
For this study, researchers gave the children tests that look at their decision-making processes. In the first such studies in children, the researchers found small to moderate improvements in children who exercised as well as a hint of increased math achievement.
“We have a number of studies conducted with animals that examined what influence physical activity has on blood flow, metabolic activity, brain function, glucose regulation, and they all demonstrate the same theme: that physical activity done on a regular basis has a protective effect,” says Dr. Tomporowski. “It doesn’t take too much to make the leap that it might influence developing children as well.”
Looking at the children’s insulin resistance, a precursor of type 2 diabetes in which it takes more insulin to convert glucose into energy, researchers found levels dropped 15 percent in the 20-minute exercise group and 21 percent in the 40-minute group. The control group stayed about the same.
“Increasing volume of regular aerobic exercise shows increased benefits on insulin resistance in overweight children, indicating reduced risk of type 2 diabetes, regardless of sex or race,” they write.
“We also know that if you stop exercising, you lose all the benefits,” adds Dr. Davis. “Exercise works if you do it.”
Adult studies have yielded comparable findings regarding exercise’s impact on insulin resistance and cognition.
The researchers tested oral glucose tolerance, measuring insulin response after children drank a small amount of glucose, before and after the studies. “Once your glucose levels start to rise, it’s called impaired glucose tolerance and that is a precursor of diabetes. It’s called pre-diabetes now,” says Dr. Davis, noting that overweight children typically have higher insulin resistance than their leaner peers. Insulin resistance is an early sign of diabetes risk that appears before glucose levels start to rise. Growth associated with puberty can temporarily increase insulin resistance, Dr. Davis notes, so because some of the children were beginning puberty, they made adjustments for the level of sex hormones.
DEXA scanning, which uses a small amount of radiation to quantify bone, tissue and fat, was used to accurately assess body composition. Executive function was measured using the Cognitive Assessment System and math skills using the Woodcock Johnson Test of Achievement III.
“If physical education were ideal, which it’s not – it’s not daily and it’s not active – then children could achieve this within the school day,” Dr. Davis says, pointing to benefits derived by children exercising just 20 minutes a day. “We are not there. To achieve maximum benefit, we were able to show it will take more than PE.”
Osteoporosis: Calcium and exercise to strengthen the bones – do you get enough?
Exercise strengthens the bones and might help reduce the risk of falling
Some people believe that they can best protect themselves by not moving around too much and trying to avoid situations where they might have a chance of falling. But in reality being too immobile is one of the major risk factors for osteoporosis. If you spend a large part of the day sitting or lying down, your bones are more likely to become weak and brittle. Physical activity that involves carrying your weight can actually strengthen your bones. One of the easier ways to get exercise with a low risk of injury is brisk walking. According to the Institute, even in older age, walking is a simple way of getting enough exercise that people feel comfortable with - and it benefits more than the bones, as well.
Professor Sawicki said: "Injury is of course always possible when you exercise. But people who are more active strengthen their muscles and bones - and that can help them stay physically stable and secure. People may gain more confidence in their bodies and that might mean a lower risk of stumbling and falling."
Can exercise prevent a severe stroke?
A new study shows that people who are physically active before suffering a stroke may have less severe problems as a result and recover better compared to those who did not exercise before having a stroke. The research is published in the October 21, 2008, print issue of Neurology®, the medical journal of the American Academy of Neurology.
The study found that the top 25 percent of people who exercised the most were two-and-a-half-times more likely to suffer a less severe stroke compared with people who were in the bottom quarter of the group. The most active also had a better chance of long-term recovery.
New MU Study Indicates that Exercise Prevents Fatty Liver Disease
Oct. 29, 2008
It’s easy to go to the gym on a regular basis right after a person buys the gym membership. It’s also easy to skip the gym one day, then the next day and the day after that. A new University of Missouri study indicates that the negative effects of skipping exercise can occur in a short period. The researchers found that a sudden transition to a sedentary lifestyle can quickly lead to symptoms of nonalcoholic fatty liver disease (hepatic steatosis), which affects at least 75 percent of obese people.
“We found that the cessation of daily exercise dramatically activates specific precursors known to promote hepatic steatosis,” said Jamal Ibdah, professor of medicine and medical pharmacology and physiology in the MU School of Medicine. “This study has important implications for obese humans who continually stop and start exercise programs. Our findings strongly suggest that a sudden transition to a sedentary lifestyle increases susceptibility to nonalcoholic fatty liver disease.”
Nonalcoholic fatty liver disease is a reversible condition that causes fat to accumulate in liver cells of obese people. As Westernized societies are experiencing a weight gain epidemic, the prevalence of the disease is growing, Ibdah said.
In the study, researchers gave obese rats access to voluntary running wheels for 16 weeks. Scientists then locked the wheels, and transitioned the animals to a sedentary condition. After 173 hours, or about seven days, the rats began showing signs of factors responsible for promoting hepatic steatosis. In the animals tested immediately at the end of 16 weeks of voluntary running, there were no signs of hepatic steatosis.
“Physical activity prevented fatty liver disease by 100 percent in an animal model of fatty liver disease,” said Frank Booth, a professor in the MU College of Veterinary Medicine and the MU School of Medicine and a research investigator in the Dalton Cardiovascular Research Center. “In contrast, 100 percent of the group that did not have physical activity had fatty liver disease. This is a remarkable event. It is rare in medicine for any treatment to prevent any disease by 100 percent.”
The study, “Cessation of Daily Exercise Dramatically Alters Precursors of Hepatic Steatosis in Otsuka Long-Evans Tokushima Fatty (OLETF) Rats,” was published in The Journal of Physiology.
