Last Paper of My Undergrad Career

Here's the last paper I will write as an undergrad. It is for my class on the physiology of aging. Please excuse any typos, bad grammar, or stylistic weirdness. I finished it on Tuesday at about 1 a.m and had to be up to train my 6 a.m. client, so the last part is prolly a little disjointed.

But enough with the prefacing! (Let me know what you think, and I'll disclose what the grade is when the professor hands them back in the next week or so.)

Vigorous vs. Moderate Activity in the Elderly

or

Don't Let Granny Lift Weights that Weigh Less than Her Purse

The American College of Sports Medicine asserts that “exercise is medicine.” If that is true, can one overdose on it?

For many years, it had been thought that moderate activity is as good as vigorous activity for reducing risks brought on by “lifestyle diseases”. People were advised that walking for 20 minutes three times per week was all that was necessary to keep them healthy. Older adults, especially, were not encouraged to perform vigorous exercise. As recently as 1992, the journal American Family Physician in an article on “Promoting and Prescribing Exercise for the Elderly” noted that “...sedentary patients should begin at a very low level and gradually progress to a goal of moderate activity” (emphasis mine) (Nied & Franklin, 2002, p. 421) .

Perhaps this is because hard exercise is, well, hard. It hurts. As Bruce Grierson puts it in a New York Times Magazine article on 90-something track star Olga Kotelko (2010), “Exactly how exercise affects older people is complicated. On one level, exercise is a flat-out insult to the body. Downhill running tears quadriceps muscles as reliably as an injection of snake venom. All kinds of free radicals and other toxins are let loose.”

And there is some evidence that, at least for some markers of disease, moderate walking can be as protective as more vigorous exercise. Risk of cardiovascular disease, for instance, seems to decrease

almost as much with moderate exercise as it does with more vigorous exercise as reported in 'Walking Compared with Vigorous Exercise for the Prevention of Cardiovascular Events in Women.” (Manson et al, 2002). The study concluded “Although vigorous exercise should not be discouraged ... our results indicate that moderate-intensity exercise confers substantial health benefits for post-menopausal women.” (p. 724) However, the authors also observed that there was a strong dose-response gradient between the physical activity level and the reduced risk of cardiovascular disease. (p. 723). In fact, the women in the study who had the best outcomes were those who did both moderate walking and more vigorous exercise.

But while heart disease and stroke are still widespread and potent enough to number among the top five causes of death in the U.S. (CDC, 2008) , cardiovascular disease is not the only challenge to the health of the elderly. Increasingly metabolic syndrome, a cluster of risk factors that, when they occur together, increase the likelihood of coronary artery disease, stroke, and type 2 diabetes. Two of the most important risk factors for metabolic syndrome are excess fat around the midsection and insulin resistance.

Studies in middle-aged adults have shown that high-intensity exercise is beneficial in reducing abdominal fat. Irving (2009) found that compared to low-intensity training, high-intensity exercise training “significantly reduced total abdominal fat, abdominal subcutaneous fat, and abdominal visceral fat.” (p. 1863). And, indeed, with regard to body composition, it appears that older adults react the same way to high-intensity exercise as other adults. In a study that looked at high-intensity exercise in men and women aged 65-90 years, the researchers split the participants into three groups. The control group did nothing. The low-intensity group exercised at 50 percent of their VO_2PEAK; the high-intensity group at 75 percent of their VO_2PEAK. Although both groups were standardized to work off 1,000 calories a week in exercise, only the high-intensity group enjoyed decreased levels of abdominal visceral fat. (Coker, 2009)

Despite the benefits of high-intensity endurance exercise, trainers are often loath to prescribe it for their elderly clients. Perhaps this is due to the fear of injury. A 1991 study, however, looked at high-intensity treadmill incline walk training and incidence of injury and noted that while injuries did occur, they seemed to be more related to fast walking than incline or intensity. (Carroll, 1991)

The benefits of high-intensity vs. moderate training seem to be even more pronounced as we move from endurance training to strength training. Human aging is associated with losses in lean muscle tissue, especially in type II fast-twitch fibers. Losing muscle mass leads to a changed body composition with a lower percentage of muscle and a higher percentage of fat. Therefore, holding on to muscle as we age is crucial (as is starting in the aging process with a healthy body composition that includes a high percentage of lean muscle mass).

In a study of previously untrained men 60-75 years old who underwent an 18-week strength training program featuring high-intensity lower-body weight training, the subjects derived many benefits from this high-intensity work, including significant gains in strength and concomitant decreases in percent body fat. The authors note that “Although recommendations of exercise training intensity and duration for aging subjects have been, for the most part, quite conservative, it is clear that not only is it possible for elderly people to tolerate resistance training of high intensity ... but that a regiment of this type may be necessary to elicit optimal physiological responses in this age group.” (emphasis mine) (Hagerman, 2000, p. 336)

In fact, the benefits of high-intensity strength training and aging are not limited to the young-old. A study of frail nonagenarians subjected to high-intensity quadriceps training developed increased muscle mass and increased strength. (Fiatarone, 1990)

But aging successfully doesn't just mean maintaining the correct body composition. The elderly often struggle with activities of daily living, whether it's putting a bag of cat food into their grocery carts or hustling for the bus. In addition, successful aging also requires maintaining cognitive function as well as positive emotions. High-intensity exercise can help with that, too. When Spanish researchers gave 62 women older than 65 a high-intensity strength traiining regimen to follow five days a week for five months, they not only increased their strength considerably (and lowered their resting heart rate), they also gained in cognative ability, reduced their anxiety, increased their internal locus of control (especially important in the elderly, who may feel others are controlling their lives), and gained social resources. In fact, the subject's quality of life was not even lowered by training fatigue or muscle soreness.(Cancela Carral, 2007, 544)

Conclusions

As the population that is in middle-aged now (and struggling with the many health challenges that come with the greater levels of obesity prevalent in the population) ages into senior-hood, society will continue to feel the burden of a population that is skeptical of vigorous physical activity.

Increasingly, researchers are finding that, when it comes to exercise, less isn't more. In many of the studies examined for this assignment, benefits of exercise rose on a curve that was twinned with the intensity, duration, or volume of exercise.

Health officials have long been tentative in their recommendations for exercise. Maybe that's because they believed if people know that exercise should be somewhat difficult in order to make gains, potential exercisers would be scared off of exercise before they even started. Yes, three or four half-hour walks a week is better than sitting on the couch, but letting people think that they can lose significant amounts of weight or gain significant amounts of strength with those walks is not really fair.

Because of the physiological decline in muscle mass that occurs as we age, the elderly perhaps stand to gain the most from honest encouragement toward more vigorous activity, and yet, ironically, no group has received more tentative exercise prescriptions than the aged.

Of course, the potential for overuse injuries and other disabling bodily problems is always there when you partake of high-intensity exercise. But in the U.S., in 2010, a far, far greater proportion of the population is ending up with bad health outcomes from exercising too mildly than from exercising too vigorously.

References

Cancela Carral, J.M., Ayan Perez, C., (2007) Effects of high-intensity combined training on women over 65. Gerontology, 53, 340-346.

Carroll, J.F, Pollack, M.L., Graves, J.E., Leggett, S.H., Spitler, D.L., & Lowenthal, D.T. (1991) Incidence of injury during moderate- and high-intensity walking training in the elderly. Journal of Gerontology, 47(3), M61-M66.

Center for Disease Control. (2008). Mortality Rates [Data File]. Retrieved from http://www.cdc.gov/nchs/fastats/deaths.htm

Cooker, R.H., Williams, M.S., Kortebein, P.M., Sullivan, D.H. & Evans, W.J. (2009) Influence of exercise intensity on abdominal fat and adiponectin in elderly adults. Metabolic Syndrome and Related Disorders, 7(4), 363-368.

Fiatarone, M.A., Marks, E.C., Ryan, N.D., Meredith, C.N., Lipsitz, L.A., Evans, W.J. (1990) High-intensity strength training in nonagenarians. Journal of the American Medical Association, 263(22), 3029-3034.

Grierson, B., (2010, November 28) The incredible flying nonagenarian. New York Times Magazine. Retrieved from http://www.newyorktimes.com/2010/11/28/magazine/28athletes-t.htm

Hagerman, F.C., Walsh, S.J., Staron, R.S., Hikida, R.S., Gilders, R.M., Murray, T.F., Toma, K, & Ragg, K.E. (2000) Effects of high-intensity resistance training on untrained older men. I. Strength, cardiovascular, and metabolic responses. Journal of Gerontology, 55A(7), B336-B346.

Irving, B.A., Davis, C.K., Brock, D.W, Weltman, J.Y., Swift, D., Barrett, E.J., Gaessner, G.A., & Weltman, A. (2008) Effect of exercise training intensity on abdominal visceral fat and body composition. Medicine and Science in Sport and Exercise, 40(11), 1863-1872.

Manson, J.E., Greeland, P., LaCroix, A.Z., Stefanick, M.L., Mouton, C. P., Oberman, A., Perri, M.G., Sheps, D.S., Pettinger, M.B., Siscovick, D.S. (2002) Walking compared with vigorous exercise for the prevention of cardiovascular events in women. New England Journal of Medicine, 347(10), 716-725.

Nied, R.J, & Franklin, B., (2002) Promoting and prescribing exercise for the elderly. American Family Physician. 65(3), 419-427.