EXERCISE AND AGING: A Qualitative Correlation
In 1523 the Spanish explorer and conquistador Ponce de Leon went searching for the legendary Fountain of Youth. What he discovered was Florida; not quite the quick-fix of a magical substance flowing from a fountain but a nice place for frozen northeastern residents to go for recreation in the winter. The idea of mythical youth is still very much alive in our culture and most noticeable in the advertising that surrounds us. But beyond the youthful look presented us, we desire to actually be youthful & #8212; to act and feel youthful & #8212; to feel like eighteen again (or at least twenty-five). This is one of the ironies of life. Throughout childhood you can’t wait to be an adult. Then, once you’ve been an adult for a while, you’d do anything to be young again. Physical exercise is one “anything” a person can do to not only feel young but to physiologically slow the aging process.
This paper will present studies indicating the affect exercise has on the human body and how it is useful in keeping us at our optimum physical and mental health. For now, aging is inevitable. Physiologically, we age because individual cells are preprogrammed to overwork and then self-destruct. The process becomes apparent in a comparison of old and young skin cells. Although both types contain the same array of genes, in older cells the genes work overtime under the direction of a master gene. The master gene forces the others to produce abnormal amounts of protein, which slows down replication and other vital cellular activity. These factors eventually cause organ degeneration and aging.
To prevent or delay aging a way must be found to control overactive genes, say Dr. Samuel Goldstein of the University of Arkansas and Anna McCormick, Ph.D. of the National Institute on Aging. The ultimate anti-aging discovery would be a drug that could suppress the master gene, stopping cells from beginning their destructive course. Until this discovery (and well after) our anti-aging bullet can be exercise. Exercise is the closest thing to an anti-aging pill there is, says Alex Leif, M.D., a professor at the Harvard Medical School of Gerontology. “Regular daily physical activity has been a way of life for virtually ever person who has reached the age of 100 in sound condition.” Studies at the National Institute of Aging have repeatedly shown that regular exercise and strength training can have a profound effect on the rate of human aging, and may forestall the disability and diseases we are used to thinking of as the unavoidable price of growing old.
One method of exercise is called strength raining attained by muscle resistance movements such as those provide by the simple use of free weights. Dr. Evans, of the Human Nutrition Research Center on Aging at Tufts University, conducted an unorthodox study that included putting 90-year-olds through an intensive weight-lifting regimen ; #8212; a practice doctors once thought would shatter bones. Dr. Evans found that strength training can increase muscle function by 200 to 300 percent. “We can make a 95-year-old as strong as a 50-year-old person, and a 64-year-old as physically fit as a healthy 30-year-old,” Evans said. “And if there are no underlying disorders, mental sharpness is retained.” What’s more, after participating in Dr. Evans study, a few of the more frail of these senior body builders were able to shed their wheelchairs.
In addition to strength training, aerobic exercise can vastly improve the health of seniors. Only 9% of Americans over age 65 do some form of regular exercise, according to Dr. Xakellis, of the University of Iowa College of Medicine. Studies have shown that sedentary people run twice the risk of heart disease as active people. Coronary artery disease accounts for almost half of all death in the US. The proper aerobic exercise-at any age-increases strength, keeps blood pressure down and increases bone mass. Not to mention that by burning 3,500 calories a week, the risk of early death can be reduced by 50%, says Muscle and Fitness Magazine. My level of preference is to burn this number of calories through workouts daily or at a minimum of 1,000 calories a day. With exercise and proper care, seniors (65+) no longer need to be pushed in a wheelchair; they’ll be too busy deciding whether to go scuba diving or white-water rafting.
Not too long ago, serious runners stopped competing past their prime years when their times began to slow noticeably. However, the aging of the 1970’s “running boom” generation has heightened the interest in masters running (40 years and over) with each passing year. Consequently, more and more runners look forward to competing within new age categories and measuring themselves against their age-group standards. This has made running a much more interesting sport for runners of all ages and ability levels. The first major breakthrough in age group running came when Jack Foster of New Zealand ran a rather “youthful” 2:11 for the marathon to shatter the existing masters world record for the distance. Foster later was the first runner in his fifties to run 2:20 for the marathon (1). Then at the 1984 Olympic games in Los Angeles, Portugal’s Carlos Lopes, at the age of 37, stunned the running community by winning the gold medal in the marathon in Olympic record time. A year later, Lopes went on to set the world record (2:07:11) in winning the 1985 Rotterdam Marathon (2). Although research shows that runners’ VO2max values decline by about 5 percent per decade, several studies have revealed that high intensity training can forestall a significant amount of this decline. Since then, elite male and female masters runners have begun to increasingly challenge and compete on equal ground with some of the top open runners in major road races around the world.
Unlike the open competition category, the masters’ age-group record books are being continually rewritten. Age-group superstar Derek Turnbull, 65 (also from New Zealand), destroyed six world records (65-69 age-group) ranging from 800 meters to 10,000 meters within a five-week period. His sensational string of performances included eye-opening times of 4:56 for the mile, 16:38 for the 5K, and 34:42 for the 10K distance (3). While racing performance undoubtedly slow with age, these runners are showing remarkable performance past the age of 35, when it used to be generally agreed that athletes were well past their prime years.
Although the various systems of the body slow down with age, running greatly reduces the rate of the aging process. A major predictor of performance ability among runners is one’s aerobic capacity, or VO2max. Most researchers agree that the rate of decline in the aerobic capacity of runners is about half that of sedentary people. In fact, it has been shown that runners’ VO2max values actually decline at about five percent per decade versus ten percent per decade for their inactive peers (4). Moreover, several studies have shown that significant declines in aerobic capacity can be forestalled with high intensity training (5). The bias of this writer regards running as emphasizing distance or endurance. Weight-bearing activities, such as running, add mass to your bones. Daily exercise is especially important for women, since they have comparatively lower bone mass than men throughout their lives. Inactive women above the age of 35 will generally lose about one percent of their bone mineral content per year (6). However, endurance training helps keep one’s bone structure similar to that of a young adult. This idea was documented in a study of male marathoners who showed no decline in skeletal mass with age (7).
Running also significantly reduces the risk for developing most cardiovascular diseases that increasingly occur in older adults. A strong predictor of coronary heart and artery disease is a high level of a particular type of cholesterol in the body, called low-density lipoprotein. Several reports have shown that high intensity training, such as running, greatly reduces these unfavorable cholesterol levels. Furthermore, intense training increases the level of protective cholesterol in the body, aiding the heart in pumping more blood with less effort and making the functions of the circulatory system much more efficient than those of sedentary individuals (8).
Another consideration of the aging human concerns declining aerobic capacity and muscle strength. While the body benefits in many ways from endurance training, aging still naturally takes its toll on the systems of the body. Consequently, running performances tend to decline regardless of ability level, beginning in your mid-thirties.
The two functional areas most affected by the aging process are aerobic capacity and muscular ability. These capacities are reduced primarily because of declines in 1) cardiac output, 2) lung elasticity, 3) the amount of lean muscle mass, and 4) muscular flexibility. The topic of aerobic capacity has been studied extensively among master runners to find some answers behind the decline with age. One reason attributed to the reduction in VO2max is the slower functioning of the central circulatory system (9). With aging, maximal cardiac output diminishes, causing the heart to beat slower and pump less blood with each beat. This is why maximum heart rate decreases with age.
A second explanation for lower aerobic capacity with age is the reduced ability of the lungs to take in and release air quickly. This restriction in airflow is caused by a loss of lung elasticity (10). Consistent high-intensity training and racing can maintain lean muscle mass and muscle strength favorably versus less intense training. In both cases, the circulatory and respiratory systems of older runners cannot perform as efficiently as those of younger runners during high intensity exercise. In essence, running performance becomes gradually limited by the declining capabilities of the heart and lungs.
Muscular strength is another major limiting factor in performance for older runners. We lose strength as we age primarily due to a loss of lean muscle mass. The actual number of muscle fibers decreases over time. Initially we lose the fast twitch fibers we used so frequently in our younger days, followed by a loss of the remaining slow twitch “endurance” fibers (11). After age thirty the average American loses muscle fibers at a rate of about three to five percent per decade, resulting in as much as a thirty percent loss of muscle power by age sixty (12). Of course, the rate is much less for runners.
Although the aerobic capacity of older runners is lower than their younger counterparts, older runners can run at a higher percent of their aerobic capacity. Since running concentrates on building the lower body, runners can usually maintain relatively good muscle mass in their legs. However, they often lose up to four pounds of muscle mass per decade in the upper body (13). Consequently, these lean muscle fibers are usually replaced by fatty tissue. Our muscles also stiffen over time if we fail to stretch routinely. The connective tissues between the muscles and bones become more rigid as we age. This inflexibility of the connective tissues becomes the most integral element in limiting a person’s range of motion (14).
An older runner with limited range of motion gradually develops a shorter stride length making each step require more effort. However, superior muscle cells are found in older runners, i.e. masters (over forty years).
Despite the loss of lean muscle mass, power, and flexibility with age, the cumulative effect of years of running often produces certain advantages in the muscle cells of masters athletes, counter-balancing some of these losses. In fact, masters’ athletes are capable of endurance performances equal to those of non-elite young runners, despite having a lower VO2max. The superior oxygen-processing capabilities of their muscle cells allow them to use a higher percentage of their VO2max during competition (15). According to a recent study, older runners, whose average age was 63, were matched with younger runners in their mid-twenties who had similar 10K race times and training schedules. Even though the older runners had fewer muscle fibers, lower VO2max values, and less muscular power, their muscle cells were found to have as much as 31 percent more oxidative enzyme activity. This superior enzyme activity, developed through years of training, enabled their working muscles to process oxygen and remove lactic acid more efficiently (16).
There may be ways of “mastering” the effects of aging. Several reports have indicated that even among trained athletes, the intensity of training plays a major role in determining the amount of decline due to aging. Among a recently studied group of national masters track champions, it was found that those runners who maintained a high level of training intensity and competition frequency showed less of a loss in performance time, aerobic capacity, and lean body mass than those who cut down on their frequency of competition and training intensity. In addition, those who maintained a well-rounded weight-training program actually maintained their total lean muscle mass over a ten-year period (17). It appears that continuing a well-rounded, high intensity training program helps produce excellent masters racing performances. Hal Higdon, senior editor for “Runners’ World” and a three-time masters world champion, suggests that older runners wanting improvement should continue to increase mileage levels without over-training.
Nearly every study of older adults (up to 96 years old) has found that those who perform a well-rounded weight-training program can increase muscle mass, strength and mobility. Higdon adds that when mileage cannot be increased, masters runners should turn to higher quality training – quickening the pace of their normal training runs and starting or continuing to do speed workouts, such as interval training.
Finally, Higdon advocates at least two days of easy running between quality workouts for older runners since their recovery time is longer (18).
Although there are no studies that have shown that weight training improves distance-running performances, the loss of lean muscle mass in older runners is not desirable. In order to offset the loss of lean muscle mass, weight-training programs that build strength while avoiding extra bulk are advised for masters’ runners. Nearly every study of older adults (even as old as 96 years of age) who undergo an organized weight training regimen reports significant gains in muscle size, strength, and mobility (19). If the muscles of inactive individuals past the age of 90 can respond favorably to weight training programs, certainly many runners can benefit from following such a routine.
Again, the resistance to injury alone makes weight training worthwhile for runners. The ultimate goal, though, is to train more intensely to forestall the effects of aging on performance. In order to maintain a flexible muscular system, a consistent stretching program that incorporates an exercise for each of the major areas of the body should also be adopted. Studies have shown that at any age with proper training both retention of lean muscle mass and overall bodily function and improvement will occur, but the rate of improvement will not be the same at every age.
In conclusion, masters athletes must counter the tendency to lose lean muscle mass, flexibility, and aerobic capacity. This message extends beyond “athletes”. We all can benefit from some level of moderate exercise but as has been shown, optimum levels of balanced, daily exercise, at age threshold levels is best. Intense, well-rounded training programs that include stretching, strength work, with more carefully planned recovery days, will not only forestall these losses but will probably enable physical health and performance to improve with respect to age-group standards no matter what level of exercise intensity a particular individual may be involved with. Furthermore, the brain chemistry and psychology of exercise (good topic for another paper) are major driving forces that keep me involved in tri-athlete activities—and what most endurance and extreme sports are all about.
1J. Fixx, Maximum Sports Performance, Random House, New York, NY, 1985, pp. 118-119.
2T. Noakes, Lore of Running, Leisure Press, Champaign, IL, 1991, pp. 316-317.
3A. Sheahen, ed., “Turnbull Sets Six World Records,” National Masters News, Van Nuys, CA, Issue No. 165, May 1992, p. 16.
4M. Rogers, et. al., “Decline in VO2max with Aging in Master Athletes and Sedentary Men,” Journal of Applied Physiology, Vol. 68, No. 5, 1990, p. 2195.
5F. Kasch, et. al., “A Longitudinal Study of Cardiovascular Stability in Active Men Aged 45 to 65 Years,” The Physician and Sports medicine, Vol. 16, No. 1, Jan. 1988, p. 117.
6E. Smith, “Physical Activity and Calcium Modalities for Bone Mineral Increase in Aged Women,” Medicine and Science in Sports and Exercise, Vol. 13, No. 1, July 1980, p. 60.
7J. Aloia, Osteoporosis, Leisure Press, Champaign, IL, 1989, p. 29.
8D. Seals, “Effects of Endurance Training on Glucose Tolerance and Plasma Lipid Levels in Older Men and Women,” Journal of the American Medical Association, Vol. 252, No. 5, Aug. 1984, pp. 645-649.
9G. Heath, “A Physiological Comparison of Young and Older Endurance Athletes,” Journal of Applied Physiology, Vol. 51, No. 3, Sept. 1981, p. 639.
10B. Johnson, “Flow Limitation and Regulation of Functional Residual Capacity during Exercise in a Physically Active Aging Population,” American Review of Respiratory Disease, Vol. 143, No. 5, May 1991, p. 960.
11, 15, 16 A. Coggan, “Histochemical and Enzymatic Characteristics of Skeletal Muscle in Masters Athletes,” Journal of Applied Physiology, Vol. 68, No. 2, 1990, pp. 1896-1900.
12, 13, 18 H. Higdon, The Masters Running Guide, National Masters News, Van Nuys, CA, 1990, pp. 36-37, pp. 48-51.
14, 20 M. Alter, Science of Stretching, Human Kinetics Books, Champaign, IL, 1988, p. 31, p. 64.
17 G. Legwold, “Masters Competitors Age Little in TenYears,” The Physician and
Sports Medicine, Vol. 10, No. 10, Oct. 1982, p. 27.
19 M. Fiatarone, “High-Intensity Strength Training in Nonagenarians,” Journal of the American Medical Association, Vol.. 263, No. 22, June 1990, p. 3033