Exercise to Live, Or Live to Exercise?

By Jay Goldstein, DPM, MS


Q: I have trouble balancing health and time commitments with recurrent tendinitis. I am never quite sure whether I am over-exercising or under-exercising. How much is enough?

A: It depends on your goals.

In the 1991 winter issue of The Oregon Distance Runner, I reviewed a lecture given by Dr. Kenneth Cooper, the "father" of aerobics. On the basis of a very large study that he conducted, your level of health (in comparison to a couch potato, all other factors being equal) would be significantly improved by performing relatively small amounts of exercise:

  1. walking two miles at a 15 minute/ mile pace three times weekly
  2. walking two miles at a 20 minute/ mile pace five times weekly
  3. walking three miles at a 15 minute/ mile pace two times weekly
Any one of these would be considered quite easy by most readers of The Oregon Distance Runner.

Presumably, proper medical attention to your tendon, and the above (relatively easy) exercise schedule, would lead to resolution of your chronic injuries.

However, some people exercise for many other reasons such as weight control, social interaction, stress reduction, and love of exercise. The above schedule might not meet those needs.

Research

Research during the past several years is pertinent to your concerns. Unfortunately, the results of the research (or should I say the interpretation of the research) is not completely clear.

In 1962 and in 1966 questionnaires were sent to over 20,000 male Harvard alumni. Their average age was 46 years. Anyone with cancer, or chronic lung or heart disease, was eliminated from the study, leaving over 17,000 men still included in the study. Their energy expenditure was categorized into non vigorous (e.g., slow walking) and vigorous activities (e.g., running, swimming, tennis). Their total weekly energy expenditure was then divided into five categories based upon quantity and type (vigorous or non vigorous). The research team then determined the number of deaths (for any reason) from the time of the questionnaires (1962 or 1966: through 1988.

Results

There was no correlation between the number of deaths and energy expenditure based upon non vigorous activities. There was a strong correlation between the number of deaths and energy expenditure based upon vigorous activities. The greater the energy expended on vigorous activities at the time of the questionnaires, the more likely the alumni were still living in 1988. A slightly confusing piece of data was that the death rate rose slightly among the most active groups (a 150 lb. man running 26 miles weekly at an 8 minute/mile pace). However, when the researchers used data from questionnaires sent out in 1977 (presumably a more accurate correlation), the death rate continued to drop even for the most active alumni.

Say It Ain't So, Ken

Just when highly devoted exercise fanatics of the world were beginning to feel smug, many researchers, including "Father Cooper" began to identify nasty ions (molecules) that apparently are produced by tissue damage, damaged during exercise! These nasty molecules damage cells, and may be responsible for increasing the death rate. Although this research has been developing for over ten years, it is not clear to me at what level, if any, the damage caused by these molecules (called free radicals) offsets the plethora of well- documented benefits of routine exercise. In fact, some research suggests that athletes are better able to tolerate these uninvited and unwanted pests.

Antioxidant Supplements

Some researchers have suggested nutrition supplements, such as vitamins A,B,C,E, and selenium, would help to fight the evil free radicals. The results of this research have been mixed, and some of the larger more recent studies on antioxidant supplements have failed to demonstrate any benefits.

Where Does this Leave Us

Rest assured that many more words will be written about the advantages and disadvantages of exercise, and about the (postulated) battle between antioxidant supplements and the evil free radicals. For now, the following suppositions seem reasonably safe:

  1. Ten miles of walking weekly will provide significant health benefits.
  2. Fifteen miles of jogging weekly will provide health benefit and probably increase your life span.
  3. If you exercise too much, you are more likely to become injured, especially as the years (age!) progress.
Therefore, it behooves everyone to have more than one form of exercise, involving a variety of joints and muscle groups. How much should you exercise? It depends upon your goals.

References

    Ainsworth, BE, et al., Compendium of physical activities, Med Sci Sports Exerc., 1993; 25:71-80
    Alessio, HM Exercise induced oxidative stress, Med Sci Sports Exerc., 1993; 25:218-24
    Cooper, KH, Controlling Cholesterol, Bantam, NY, 1988
    Cooper, KH, The Antioxidant Revolution, Inkslingers Inc., 1994
    Cooper, KH, Running Without Fear, M. Evans & Co. Inc., NY, 1985
    Harris, B, Experience Required, Shape, 13:1, 1993
    Lee. MI. et al., Exercise Intensity and Longevity in Men, JAMA, 1995 273:1179-84

Dr. Goldstein is an Oregon Road Runners Club member and has been running for 31 years. He is Board Certified in Podiatric Surgery, Podiatric Orthopedics, and in Podiatric Medicine.


Copyrighted by Jay Goldstein who reserves all rights to republication.