Some people — who are they? — have no problem fitting regular aerobic exercise into their lives. The rest of us want to know how much we have to exercise to see health benefits. Now we have some answers: You may want to go just a tad longer and harder than you'd thought.
Current government guidelines advise adults to get the equivalent of at least 2 1/2 hours of moderate-intensity aerobic exercise or 75 minutes of higher-intensity exercise every week, plus some strength training. In effect, those guidelines say there's no particular benefit from working out harder, other than saving time.
To find out if that's true, researchers at Queen's University in Ontario studied different combinations of exercise intensity and duration in a group of 300 sedentary adults with abdominal obesity. (That's generally defined as a waist circumference of more than 35 inches for women who aren't pregnant and more than 40 inches for men.) People with abdominal obesity are at higher risk of heart disease and early death than people with slimmer waistlines.
Methods of Study
All the exercisers were told to work out under supervision five times per week for 24 weeks. One (1st) group worked out at low intensity, about 50 percent of maximum oxygen uptake (VO2 max, a measure of cardiovascular fitness), for about 31 minutes per session — enough to burn 180 calories for women and 300 for men. That exercise prescription was about the same as in the government guidelines. The intensity was about equivalent to walking slowly, said study a