EXERCISE…HOW MUCH IS ENOUGH TO GET HEALTH BENEFITS

LIVE LONGER AND AVOID DISEASE

On a summer day more than a year ago (July 29, 1993, to be exact), Dr. Walter Dowdle, acting director of the Centers for Disease Control and Prevention (CDC), stepped to a podium in Washington, D.C. and made an announcement that was to receive wide media attention. Speaking at a news briefing sponsored by the American College of Sports Medicine (ACSM), Dowdle announced a new, updated recommendation concerning physical activity:

Every American adult should accumulate 30 minutes or more of moderate-intensity physical activity over the course of most days of the week. Because most Americans do not presently meet the standard described above, almost all should strive to increase their participation in moderate and/or vigorous physical activity.

Collectively dubbed “Exercise Lite,” the explanatory guidelines presented in the news briefing addressed the core issue of what actually constitutes appropriate physical activity for health purposes, and how much of that activity is really enough. Jointly issued by the CDC and ACSM, the new guidelines called for a half hour of activity at least five days a week. Somewhat surprisingly, according to the guidelines, it is not necessary to engage in physical activity for 30 consecutive minutes, but merely a total of 30 minutes throughout the day. What changed most dramatically, however, is the definition of “exercise.”

The term exercise would henceforth be discarded in favor of the more politically palatable designation, “physical activity.” Furthermore, almost everything from working in the yard to doing household chores qualifies as physical activity. The basic message advanced by Dowdle, et al., is that if you expend an additional 200 Calories a day be engaging in physical activities that involve burning 4.5 and 6 Calories per minute by average-sized women and men, respectively, you’ll reduce your risk of contracting most diseases and you’ll live longer. Table 1 provides a list of possible activity options and their metabolic cost for a 10-minute period.

The really good news, according to the CDC and the ACSM, is that you can achieve both benefits — avoid disease and live longer — without ever going to the gym, breaking a sweat or feeling your heart pound excessively. In other words, as it was extensively acknowledged in the popular media, “exercise lite” enables individuals to be “fit without exercise.” Nothing could be better than that — or could it?

Does exercise lite work?

Given the extraordinary alterations in such exercise prescription guidelines, one critical question must be answered: Does exercise lite work? The answer is an unequivocal “yes and no.” The primary argument in support of exercise lite is that considerable evidence exists to support the notion that if a sedentary person becomes somewhat physically active (regardless of what that activity is), the life span of that individual will be extended somewhat. Such an occurrence is not all that surprising given the “law of initial values,” which, in this instance, means that if you take a totally inactive person and have that person do something, the effects of doing something will have a relatively measurable impact.

The second reason advanced for exercise lite is that it can serve as a bridge — first, to helping a sedentary person become physically active and, finally, to providing the subsequent physiological foundation for being able to engage in more demanding physical activities.

In reality, both arguments for exercise lite can be challenged. While it is true that a physically active person will likely live longer than a sedentary one, the more appropriate issue to be addressed is the quantity-vs.-quality dilemma. In other words, exercise lite may add years to your life, but does it add life to your years? Will it improve the quality of your life? In all honesty, it won’t for most people. Because exercise lite doesn’t appreciably improve your levels of aerobic fitness, muscular fitness and flexibility, you won’t be more prepared to perform the activities of daily living (at work, home and play) without undue risk of fatigue and injury. The bottom line is simple: Exercise lite may enable you to live longer, but it won’t necessarily allow you to live better.

The argument that exercise lite will somehow, someday, facilitate your transition to more meaningful forms of physical activity is also subject to serious limitations. For example, if as an exercise lite proponent the “quality” of your life is relatively unchanged from your days as a sedentary person, what will motivate you to become even more physically active? If you had neither the understanding nor the desire to exercise on a regular basis before adopting an exercise lite approach, what will enable you to progress to an even healthier, more active lifestyle? In neither instance does exercise lite appear to be the answer.

The good old standards

If exercise lite is not the answer for enhancing both the quantity and the quality of your life, at least two issues need to be addressed: First, why did exercise lite evolve in the first place; and second, how much and what type(s) of exercise should you do? The second issue involves a perfectly straightforward response, while the first inquiry involves more supposition.

Depending upon your viewpoint, exercise lite evolved either as a legitimate (but somewhat misguided) effort to get 78 percent of Americans who fail to exercise on a regular basis off their “duffs” into a healthier lifestyle, or as a concerted undertaking to raise the relative number of Americans who “exercise” simply by changing the definition of “exercise.” Critics of exercise lite argue that the latter action would be related to an organizational concern by ACSM over the failure to reach their Healthy People 2000 goal — a goal that was not being met by a long shot.

How much and what type(s) of exercise should you do? The answer is simple: Exercise on a regular basis. Always keep in mind that a major difference exists between physical activity and physical activity with a purpose. The former entails actions involving physical movement, while the latter refers to exercise.

Meaningful exercise is governed by several criteria. First, sufficient level of intensity must be reached. Second, for most people, exercise duration needs to be long enough for a training effect to occur. Finally, exercise should be performed a minimum number of times per week. Aerobic exercise, for example, must be performed by most people at an intensity level ranging from 60 to 90 percent of their maximum heart rate, for a minimum of 20 minutes, at least three times per week, in order to achieve the maximum benefits. Strength training, on the other hand, must be done at least twice a week and involve workouts consisting of a minimum of one set of eight to 12 repetitions of 10 to 12 exercises that train the major muscle groups if you want to obtain the most from your efforts. Research and common sense suggest that anything less than an appropriate level of intensity and duration will not pay the superior dividends that exercise can and should provide. From a health-care perspective, exercise is medicine; exercise lite, on the other hand, is a placebo.

Fighting an epidemic of physical inactivity

Considerable statistics confirm that America is in the midst of a serious epidemic of physical inactivity. The human and health care costs of that epidemic are enormous. The debate over the most appropriate approach to combat such a scourgeous situation will likely grow ever more contentious in the future. What is irrefutable, however, is that most Americans desperately need to achieve the medical benefits of exercise.

How to accomplish such an obvious goal will remain the focus of much discussion. The CDC and ACSM propose that exercise lite is the path to follow. Unfortunately, a close examination of the outcomes and consequences of exercise lite suggests that the realities of exercise lite don’t measure up to its promises. Until a better alternative is identified, exercise — complete with all the straining and exerting — is the best way to achieve the “light” at the end of the tunnel. With regard to “fitness for life,” the point to remember is that “there is no shortcut to success.” Wishful thinking aside, the only pathway for meaningful success involves proper exercise.

By James A. Peterson & Cedric X. Bryant

SUGGESTED REFERENCES

ACSM News Release: “Experts Release New Recommendation to Fight America’s Epidemic of Physical Inactivity.” Indianapolis, IN: July 29, 1993.

IRSA News Release: “IRSA Endorses CDC/ACSM Recommendation on Moderate Physical Activity.” Boston, MA: August 2, 1993.

Jaret, Peter. “The Great Fitness Debate.” Health, Vol. 8, No. 5, September 1994, pp. 62-71.

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