The following appeared in the editorial section of a health and fitness magazine."In a study of the effects of exercise on longevity, medical researchers tracked 500 middle-aged men over a 20-year period. The subjects represented a variety of occupations

In this editorial the author concludes that doctors should prescribe vigorous daily outdoor exercise for their patients rather than moderate exercise. To justify this conclusion he cites a study showing that men exercising vigorously every day live more longer than the men exercising mildly only once or twice a week. A careful scrutiny to this evidence reveals that it lends little credence to this argument.

First, the author provides no evidence that the study’s results are statistically reliable. To strengthen this conclusion, the study’s sample must be sufficient in size and representative of the overall population of people who exercise. For instance, in this study women are not concluded while they are not excluded in the doctors’ recommendation. Lacking evidence of a sufficiently representative sample, the author cannot justifiably rely on the results to draw any conclusion.

Second, the author unfairly assumes that the only reason contributing to the longevity for the studied men has been much more daily exercises. However, there might be more effective factors such as healthy nutrition or environment influencing longer lived men’s life. Without considering and ruling out these and other possible reasons the author cannot substantially concludes that more daily activities has merely led to their longer life.

Third, the author unreasonably concludes that doctors should recommend their all patients to do vigorous daily outdoor exercise. Although the results of the study might be attributable to the whole exercising people, they cannot be thoroughly benign or healthy for all the patients. For instance, some patients might suffer from chronic diseases such as heart problem and consequently vigorous and excessive exercises do not help them or even may harm their health.

In sum, the author fails to convince me. To bolster this conclusion he must point out other possible factors effective in increasing exercising people’s life expectancy. To better assess the strength of this argument the author’s conclusion must distinguish between different patients with different problems and diseases. I need also more information assuring me that the result of the study reflects the characteristic of the whole exercising people.