Researchers establish the effect of strength training on chronic disease prevention and increased bone mineral density.
Athletes with bulging biceps and toned calves once dominated the resistance training research studies at universities and research institutions worldwide. Today, research subjects often take the form of an 85-year-old woman in a polyester suit and pearls or an obese middle-aged man with a history of heart disease and Type 2 diabetes.
With links recently established between weight training and prevention and treatment of lifestyle-related diseases, researchers are looking at the effect of resistance training on average, sedentary individuals. It's become challenging to keep up with the latest strength training research, says Wayne Wescott, fitness research director for the South Shore YMCA in Quincy, MA.
“Researchers are still doing more and more with the athletes, but at least now we're getting a higher percentage of the studies looking at average adults and the health benefits rather than just the performance,” says Wescott, who is finishing a study on the viability of circuit strength training for Air Force personnel on Langley Air Force Base.
Just the fact that researchers are increasingly focusing on strength training is a major change. For decades, scholarly journals were flooded with articles on endurance exercise, says Michael Flynn, a professor of health and kinesiology and the director of the Max E. Wastl Human Performance Laboratory at Purdue University in West Lafayette, IN.
“Slowly over the last 15 years, there's considerable evidence that resistance training is as equally beneficial as endurance exercise and can improve lean body mass at the same time it provides other effects,” says Flynn, who has been with Purdue for nine years.
Battling Chronic Diseases
Like many researchers, Flynn studied athletes when he first began doing strength-training studies. Securing funding for studies on performance-related variables became a major challenge, so he broadened the scope of his research. He found that while no one was interested in the performance of a 38-year-old marathon runner, the funding flood gates opened when he turned his focus toward the aging population with an emphasis on chronic disease. The populous and aging Baby Boomers population has made this a hot area for research.
The American Association of Retired Persons awarded Purdue a grant in 1995, followed by grants from the National Institutes for Health and the American Heart Association as well as other sources. With the funding in place, Flynn and his research team began studying the effect of weight training on the amount of inflammation or muscle damage in older women. Rather than increasing inflammation, the study found that strength training had an anti-inflammatory effect, Flynn says.
“Once we got over the shock, we began trying to figure out how exercise exerts the anti-inflammatory effects,” says Flynn, who conducts his research in a 1,200-square-foot fitness center adjacent to the laboratory. “We found all these wonderful, interesting links between inflammation and chronic disease and how exercise blunts inflammation.”
Diabetics, the obese and individuals suffering from heart disease have a high level of inflammatory proteins, and by strength training, they could mitigate the effects of these chronic diseases, he says. While inflammation can be beneficial in strong, healthy individuals because it can help with cleanup and repair of splinters or injuries, it can lead to chronic diseases in older individuals who have a poorly regulated inflammatory process, he says.
Since Flynn and his team first started studying the anti-inflammatory effects of exercise, about 50 to 100 papers have been published on the subject, and it has evolved into a new area of research, he says.
“There are always questions that need to be answered, but the progress in this area has been fairly satisfying,” he says. “Most of the results have been very positive, and few have reported any adverse events or injuries.”
Through his research, Steven Devor, an exercise physiologist at Ohio State University (OSU) in Columbus, OH, and author of a 2005 study on mammalian skeletal tissue, found that strength-training exercise is like medicine for those suffering from a chronic disease like Type 2 diabetes, heart disease and high blood pressure, which are all directly influenced by exercise and weight loss.
“If you can get people moving and get them to embrace exercise and adapt it as part of their routine, they can often get off their medications,” Devor says.
Studies on chronic diseases often go hand in hand with research on older adults. Every seven seconds, an adult turns age 50, and if that individual doesn't strength train, he or she will lose 10 percent of his or her muscle mass every decade, says Devor, who started a research program at OSU in 1999 and oversees fitness centers at three local continuing care centers. While many seniors may think they are too old and frail to strength train, muscles never lose the ability to adapt, he says. By strength training, residents in their 80s, 90s and even 100s are boosting their self confidence and increasing their independence.
“You can almost see them walking a little taller because they can move around better and aren't afraid to take a flight of steps,” he says.
The seniors are significantly increasing their normal walking speed and “shuffling” (walking without lifting their feet off the ground) less frequently by participating in the strength training research studies, Devor says. Older adults shuffle due to a loss of strength in their hip and knee flexors.
“The next step after a shuffle is a wheelchair because they are losing more and more strength,” he says. “I've had the adult children of a woman in her 80s or 90s come up to me and tell me I've made a big difference in their mom's life because she doesn't shuffle as much and is walking a lot faster. It's one of the most gratifying things for me in my research.”
If an older adult only has time for either a cardiovascular workout or strength training, Devor suggests the senior should lift weights because of the benefits to an aging body. While adults start losing muscle mass at age 30, they can slow the decline through resistance training.
Older adults not only need strength to perform daily functions, but they also need power in their lower body to propel themselves out of a chair or climb a flight of stairs. Cody Sipe, the director of the A.H. Ismail Center at Purdue University, is conducting a two-part study at a government-supported retirement community to discover if power is more closely related to function than strength.
“It used to be that older adults shouldn't do strength training, but thanks to research by Tufts University and Wayne Wescott, they have shown that strength training is great for older adults,” he says. “Our knowledge is now moving into what is the best way for them to train.”
Power training — or lifting weights as quickly as possible and then slowly bringing them back to the starting point — may help seniors increase their level of function and independence, Sipe says. To test his hypothesis, he recruited 20 subjects between the ages of 65 and 95 to complete a 12-week program at the new Friendship House Senior Functional Fitness Center.The control group performed three sets of 10 reps on six lower-body weight machines three days a week while the experimental groups power trained at 50 percent or 70 percent of their one-rep maximum, he says.
Sipe has not yet analyzed the results from his first research group to avoid researcher bias when working with his second group of subjects. He hypothesizes that the seniors who do power training at 70 percent of their one-rep maximum will yield the best improvements overall.
“Power training may be more beneficial than strength training in improving function in older adults,” he says.
As men and women age, they not only experience a loss of muscle mass but also a decline in bone density, which can lead to osteoporosis. To strengthen their bones, many postmenopausal women increase their daily supply of calcium, but without any physical activity, the calcium is not absorbed into the bones, Devor says.When Devor does bone scans of older women, he can tell immediately who is strength training and who is sedentary.
To build stronger bones, he encourages seniors to not only strength train, but also to engage in weight-bearing cardio exercise like running and walking. While swimming and pedaling a recumbent bike provide a good form of cardiovascular exercise, they don't put a load on the bones in order to increase bone mineral density, he says.
While women may be more prone to osteoporosis, strength training is equally important for older men, Devor says. According to the National Osteoporosis Foundation, two million American men have osteoporosis, and another 12 million men are at risk for the disease. Men often have larger, stronger bones, which may be the reason men have a lower risk of developing osteoporosis than women.
Strength training can provide a way for both men and women to increase bone mineral density, produce anti-inflammatory effects to ward off chronic diseases and increase their independence and ability to live a full daily life.
“It's not about giving a 75-year-old big biceps,” Devor says. “For that age group, strength training is all about independence.”
Strength training can improve memory in older adults, especially when using higher resistance levels. While conducting a study of 210 seniors with at least one disability, researchers found that a change in resistance level during intervention was a significant predictor of memory change.
Published: Journal of Aging and Physical Activity, January 2006. Research Institution: Department of Psychology at Brandeis University, Waltham, MA. Authors: M.E. Lachman, S.D. Neupert, R. Bertrand and A.M. Jette.
Lifting weights can increase central arterial stiffness during high-intensity and high-volume training, according to a meta-analysis. The researchers also found evidence that resistance training reduces total body-fat mass in men and women and lowers blood pressure in hypertensive adults. The review examined the effects of resistance training on risk factors for cardiovascular disease such as diabetes, hypertension, dyslipidemia and advancing age.
Published: Circulation, June 2006. Research Institution: College of Health and Human Performance and the College of Medicine at the University of Florida in Gainesville, FL, and the Division of Cardiology for John Hopkins School of Medicine, Baltimore. Authors: R. Braith and K. Stewart.
A combination of upper-body resistance training and lower-body endurance training can improve endurance, strength, body composition and blood lipid profile in healthy, active elderly. Ten healthy men in their 70s participated in three, 12-minute sessions of high-intensity interval training on a bicycle along with three, 12-minute sessions of upper-body resistance exercises. By the end of the training, the men increased the cross-sectional area of their deltoid muscles and decreased their body fat by 1.3 percent and their abdominal fat by 12 percent.
Published: European Journal of Applied Physiology, June 2006. Research Institution: University of St. Etienne, St. Etienne, France. Authors: J. Verney, F. Kadi, M.A. Saafi, K. Piehl-Aulin and C. Denis.
Two sessions of progressive resistance training per week can decrease abdominal fat and significantly improve insulin sensitivity in older adult men with Type 2 diabetes. By participating in a 16-week progressive resistance training program, nine older adult male subjects with Type 2 diabetes increased their leg maximal strength by 17.1 percent and their arm strength by 18.2 percent. They also decreased their visceral and subcutaneous abdominal fat by 10.3 percent and 11.2 percent respectively.
Published: Diabetes Care, March 2005. Research institution: Research and Sports Medicine Center, Government of Navarra, Pampalona-Navarra, Spain. Authors: J. Ibanez, M. Izquierdo, I. Arguelles, L. Forga, J.L. Larrion, M. Garcia-Unciti, F. Idoate and E.M. Gorostiaga.
A lower-extremity progressive resistance training program can reduce the risk factors for coronary artery disease (CAD) for ambulatory adult women with multiple sclerosis. Twelve women participated in lower- body resistance training and strengthened their extensor and ankle flexor strength, and decreased their self-reported fatigue. Their body weight, fatness, serum glucose, blood pressure, high-density lipoprotein cholesterol and total cholesterol remained unchanged, but the number of CAD risk factors that reached the clinical threshold for each subject declined after the progressive resistance training program.
Published: Scandinavian Journal of Clinical and Laboratory Investigation, 2006. Research Institution: Department of Applied Physiology and Kinesiology, Applied Human Physiology Laboratory, University of Florida, Gainesville, FL. Authors: L.J. White, S.C. McCoy, V. Castellano, M.A. Ferguson and W. Hou
Post-menopausal women can increase their bone mineral density with a progressive, high-intensity resistance training program, according to a meta-analysis. The study involved an electronic search of multiple databases and hand searches of journals to assess the studies' quality and publication bias.
Published: Osteoperosis International, June 2006. Research Institution: Clinical Trials Research Unit, University of Leeds, Leeds, U.K. and the University of Hull, Hull, U.K. Authors: M. Martyn-St. James and S. Carroll
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