When it comes to exercise, a little bit can help a lot, say researchers at Louisiana State University in Baton Rouge.They examined the effect of the amount of exercise recommended by the NIH for overweight postmenopausal women—30 minutes or more of moderate-intensity activity on most or all days. Subjects were 464 sedentary women with a BMI of 25-43; their systolic BP ranged from 120-160 mm Hg.

Doctors randomized the women to four groups: 102 to a non-exercise control group; 155 to a 400-calorie-per-week energy-expenditure group; 104 to an 800-calorie-per-week group (the NIH-recommended amount), and 103 to a 1,200-calorie-per-week group, all for six months. Women in the exercise groups worked out 72-198 minutes a week on semirecumbent cycle ergometers and treadmills.

After adjusting for age, race, weight, and peak heart rate, the exercise groups increased their peak oxygen consumption 4.2% in the 400-calorie group; 6% in the 800-calorie group; and 8.2% in the 1,200-calorie group, compared with the controls. There were no significant changes in BP in any of the groups.

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The researchers say the most striking finding was that even women who exercised only 72 minutes a week achieved impressive fitness gains. “This information can be used to support future recommendations,” they write, “and should be encouraging to sedentary adults who find it difficult to find the time for 150 minutes of activity a week, let alone 60 minutes a day” (JAMA. 2007; 297:2081-2091).