& Joannie Dobbs Sunday
May 21, 2006
Too bad we can't put exercise in a pill
LAST week's news reported that exercise reduces the incidence of skin cancer - in mice at least. Mice with a running wheel in their cage had significantly less skin cancer after ultraviolet light exposure than mice without running wheels. We don't know if this translates to humans exactly. However, human studies have reported a decreased risk of colon cancer in physically active people.
As health professionals lament the widespread health problems associated with modern lifestyles, study after study reports the benefits of exercise in the prevention of diseases ranging from heart disease to various types of cancer, diabetes, and even Alzheimer disease.
Question: Have some of us been placed in the mouse control group without a running wheel in the cage?
Answer: Certainly, the environment that we live in may limit ready access to convenient and enjoyable physical activity. A great deal of energy used to be expended by children to get themselves to school on foot or by bicycle. Many adults had work that required them to be on their feet most of the day. Since these basic activities have changed dramatically, the daily calories needed by the average person also have declined greatly.
Simply standing up burns about twice as many calories per minute as sitting. Jogging a 10-minute mile requires 5 times the energy of sitting. To use up the calories required to swing an axe once would probably take a few thousand mouse clicks. So, in a sense, many people today have, indeed, grown up in and currently live in the human equivalent of the mouse cage without a running wheel.
Question: Are overweight and obesity just signs of too little physical activity?
Answer: The causes of obesity are very complex. However, a sedentary lifestyle may be the major contributor in more cases than previously thought. At the very least, lack of activity makes weight control very difficult for most people.
Over 50 years ago, obesity researcher Jean Mayer demonstrated that there is a strong tendency for both animals and humans to eat more calories than they expend when their level of physical activity is very low. Mayer found that even relatively modest levels of daily physical activity were adequate to get calorie intake in balance with expenditure and lead to a healthy body weight.
In so many ways, the lack of physical activity in modern lifestyles may be the major cause of many common health problems. If exercise could be put into a pill, it would be the most frequently prescribed medication in the world.
Alan Titchenal, Ph.D., C.N.S. and Joannie Dobbs, Ph.D., C.N.S.
are nutritionists in the Department of Human Nutrition, Food and Animal Sciences,
College of Tropical Agriculture and Human Resources, UH-Manoa.
Dr. Dobbs also works with the University Health Service
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