LOS ANGELES: Studies investigating the health wonders of exercise keep rolling in. But just like with eating habits, physical activity habits are tough to study in gold-standard, randomised clinical trials — after all, who would agree to be assigned to a marathoners’ group for 20 years? Instead, most researchers do the next best thing: study people’s exercise habits and see how they fare, health-wise, down the line.Here’s a snapshot of some high-profile studies that have focused on walking or other moderate-intensity physical activity:
CARDIOVASCULAR SYSTEM: This is where the mother lode of walking benefits have been found.
Some examples: The Women’s Health Initiative study (tracking 74,000 women ages 50 to 79) found a 30 per cent lower risk of cardiovascular problems (such as heart attack or stroke) for those who walked briskly for at least 22 minutes a day.
Another study of 39,000 women (the Nurses Health Study), found half the risk of coronary heart disease for women who walked at least one hour a week. Time spent walking was more important than pace.
Men benefit too: A study of 2,700 retired men (the Honolulu Heart Program) found that those who walked at least 1.5 miles a day halved their risk of coronary heart disease.
Another, of 44,000 men (the Health Professionals Follow-Up Study), found an 18 per cent lower risk of coronary heart disease for those who walked at least 30 minutes a day. In this case, how fast they walked was more important than how long.
How does it work? Moderate-intensity activity boosts levels of high-density lipoproteins (the “good” cholesterol), lowers levels of low-density lipoproteins (“bad” cholesterol), increases oxygen supply and improves heart contractions and blood pressure.
Type 2 diabetes: With 30 minutes of walking a day, you might lower your risk for developing diabetes by one-third to one-half, scientists say. At work are the same heart-healthy mechanisms, plus extras: weight loss, improved insulin response and better blood-sugar control.
Even a single bout of brisk walking can greatly improve glucose metabolism for up to 18 hours afterward; it does so by helping muscles take up glucose from the blood without using insulin (perhaps in the same way as the diabetes drug metformin.)
And if you already battle diabetes, walking might help extend your life. In a decade-long study of 1,600 people in Southern California, diabetics who walked more than a mile a day were half as likely to die of any cause than those who walked less — even after adjusting for other factors such as sex, age, weight and smoking and drinking habits.
Walking or other weight-bearing activity builds bone strength and slows the rate of bone-mineral loss as we age. In one study, postmenopausal women who walked four hours a week dropped their risk of hip fracture by about 40 per cent, with brisk walkers experiencing the greatest benefit.
Walking can reduce the risk of anxiety by about 25 per cent to 50 per cent too. One study found that over ten weeks, a physical activity regimen was as effective in reducing anxiety in patients as was standard anti-anxiety medication. Some studies suggest that longer bouts — 30 minutes of walking each day versus three ten-minutes bouts — bring about the greatest mood improvements.—Dawn/The Los Angeles Times News Service
