Physical activity and physical fitness as protection against premature disease or death.

It is known from prospective studies that the incidence of coronary heart disease (CHD) is lower in the physically active compared with the sedentary part of the population, and the rate of CHD is lower with higher fitness level. In studies where both physical activity (PA) and fitness are assessed, only fitness, and not PA, appear to be an independent predictor of mortality from CHD. It is unclear whether other fitness components than maximal oxygen uptake (Vo2max) have a beneficial effect on the rate of CHD. Further, it seems likely that there is an upper threshold of fitness (Vo2max) above which no further improvement in risk factors for CHD is found. However, most middle-aged people have fitness levels below this threshold. There is no doubt that the middle-aged sedentary person benefits from physical activity regardless of type and intensity, and it may be easier to motivate a sedentary person to carry out moderate physical activity. However, it is likely that the best effect is achieved by performing physical activity of a type and intensity sufficient to improve the fitness level. Still, recommendations of type, frequency, duration and intensity are matters of debate.