AMOUNTS OF EXERCISE MAY BE MORE IMPORTANT THAN INTENSITY

How much you exercise may be more important than how hard you exercise in terms of heart health, according to a study of sedentary overweight men and women. Researchers from North Carolina report that people who walk briskly for 12 miles (19.2 km) per week or for about 125 to 200 minutes will significantly improve their aerobic fitness and lower their risk of developing heart disease. To better understand the effects of different amounts of exercise on aerobic fitness, Brian D. Duscha from Duke University Medical Center and colleagues randomly assigned 133 overweight sedentary men and women to 7 to 9 months of no exercise; low amount/ moderate intensity exercise (the 19.2 km walkers); low amount/ vigorous intensity (19.2 km of jogging per week); or high amount/ vigorous intensity (32 km of jogging per week). The study subjects did not alter their diet. At the end of the study, all of the exercisers had improvements in peak oxygen consumption and time to exhaustion — two established markers of fitness. Interestingly, the vigorous intensity exercisers did not get any “fitter” than the moderate intensity exercisers. However, increasing the amount of exercise from 19.2 to 32 km per week — at the same intensity — provides more cardiovascular benefits. “Therefore,” Mr. Duscha and colleagues conclude, “it is appropriate to recommend mild exercise to improve fitness and reduce cardiovascular risk, yet encourage higher intensities and amounts for additional benefits.”