The affective impact of exercise intensity that slightly exceeds the preferred level: 'pain' for no additional 'gain'.

We examined the affective consequences of an exercise intensity that slightly exceeded the preferred level. Twenty-five middle-age sedentary women participated in two 20-min treadmill exercise bouts, one during which they could select the speed and one during which the speed was 10 per cent higher than the self-selected. During the bout at self-selected intensity, ratings of pleasure remained stable, whereas during the imposed-intensity bout pleasure decreased. Therefore, even a minor increase in exercise intensity beyond the level that a new exerciser would have self-selected can bring about a decrease in pleasure. Over time, such experiences could lower adherence.