The effects of fitness training on the physiological stress response

The favourable psychological and physiological profile found in fit sportsmen does not necessarily follow from their exercise behaviour. Alternatively it may depend on endowment and/or self-selection. In that case, participation in regular exercise may not always result in a reduction of susceptibility to stress. The present article reviews several well-controlled laboratory studies that have directly examined the effect of fitness training programmes on the physiological responses to a set of standardized stressors. It was generally expected that fitness training would enhance psychological stress resistance and thus mitigate the physiological response to stress. The results of most studies belie these expectations. Intensive training programmes of up to 8 months do not change stress reactivity, even if initially low fit and high stress-reactive subjects are used. The failure to find a training effect on the intensity of the stress reactions in laboratory studies does not rule out possible psychosocial effects of regular exercise on the frequency and duration of the stress reactions in real-life situations. Furthermore, although the dynamics of the physiological response to stress are not changed, there is a clear downward shift in the overall level of heart rate and blood pressure in stressful situations. Several possible mechanisms are suggested by which these training effects may help us to deal with work stress without suffering health problems.