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Physical activity improves fitness, which in turn reduces mortality.mortality. But does a dose-response relation exist? The question is important to doctors who want to encourage inactive people to exercise more but don't want to demotivate them by being unrealistic. A large trial in sedentary postmenopausal women found a significant dose-response relation between moderate intensity exercise and fitness over six months. Women who did just 72 minutes a week of walking or cycling improved their fitness (peak oxygen consumption) by 4.2% compared with controls who did no extra exercise. Women who did 136 minutes or 192 minutes improved their fitness by 6.0% and 8.2% (P for trend <0.001).
None of the women changed their diet or lost weight. Their cardiovascular risk factors did not improve, although women in the exercise groups did lose about 2 cm off their waistlines compared with controls.
The researchers say their findings should encourage people to get moving, even if they can't manage the 150 minutes a week recommended by the US National Institutes of Health (30 minutes on most days). A linked editorial (pp 2137-9) agrees: “Even a little is good; more is better.”