Bodywork by PORTER SHIMER Is exercise a cancer risk?

Press, 5 December 1985, Page 17

Bodywork by PORTER SHIMER Is exercise a cancer risk?

Bodywork is a new regular column on health and fitness issues

Q; I read recently that exercise may increase the risks of cancer. Is that true? A.* The reports you refer to stemmed from a study presented earlier this year at a meeting sponsored by the University of California and the National Foundation for Cancer Research. The study monitored the effects of vigorous exercise (two hours of treadmill running daily) on guinea pigs and rats. Findings showed that

“free radicals” (chemical particles suspected of causing cancer) were more prevalent in exercising than non-exercising animals. None of the exercising animals, however, actually developed cancer. Commenting on these results, an exercise expert, Dr Kenneth Cooper, of the Aerobics Center in Dallas, recently ' said, “I researched the medical literature and found that population studies do not support a positive exer-cise-cancer association. “On the contrary, being

more physically active may actually protect you from cancer, particularly colon cancer.” Dr Cooper reports a 1984 study of 2950 men with colon cancer, which showed that cancer was 1.6 times more prevalent in men with sedentary as opposed to active jobs. Two other studies, Dr Cooper says, have shown that exercise actually inhibits the growth of cancerous tumors in animals. “But recent studies on Harvard alumni by Dr Ralph Paffenbarger are even more impressive,” Dr Cooper says. “Men expending less than 500 calories a week in physical activity had a cancer death rate of 25.7 per 10,000 man years as compared to 19.2 for those men expending over 500 calories a week — a significant difference.” Five hundred calories,

Dr Cooper adds, “is about what you would expend running five miles.” Last but not least, Dr Cooper tells of a study done by Dr Lee S. Berk of the Loma Linda University Medical Center showing that exercise, in conjunction with the release of endorphins, produces “natural killer cells,” which are known to be cancer deterrents. In a nutshell, Dr Cooper considers the cancer-fit-ness scare to be just another cheap shot in what he calls “the ongoing attack on exercise.” @ 0 o Q.* If I get fitted for orthotics in my running shoes, will my running seem easier? A: More comfortable, maybe, but probably not easier. When researchers from the Department of Health and Physical Edu-

cation at Arizona State University tested people on a treadmill barefoot, with running shoes and with running shoes plus orthotics, they found that what mattered most in terms of “running economy” (the amount of calories burned) was the sheer weight of whatever was on the foot.

Running barefoot burned the fewest calories, running with shoes burned slightly more, and running with shoes plus orthotics burned the most. These differences were quite small, however, suggesting that the improvement in running style resulting from shoes or shoes plus orthotics was helping to offset the burden of the added weight. What’s the bottom line? If you’re running for health or weight control, add as much to your feet as it takes to make them comfortable. Not only will the additional comfort encourage you to run longer, but you’ll be burning more calories with every step. Copyright 1985. Universal Press Syndicate.