A City Guide To Ezhou for EXERCISE n exercise-induced release of the body’s own natural opiates into the blood stream, which produce a natural high’ and act as a painkiller; n stimulation of the release of catecholamines such as noradrenaline and adrenaline, which counter any stress response and enhance mood Chapters and ; n muscle relaxation, which reduces feelings of tension. However, the relationship between exercise and positive mood states is perhaps not as simple as these biological routes suggest. For example, evidence exists of an inverse relationship between exercise intensity and adherence, whereby individuals are less likely to maintain intense exercise than moderate exercise, possibly because it is experienced as adversive Brewer et al. . This suggestion that, beyond a certain level, exercise may in fact be detrimental to mood has been explored further by Hall et al They examined the affective response of thirty volunteers to increasing levels of exercise intensity and found not only that intense exercise caused negative mood but also that the timing of mood assessments pre- and post-exercise assessment, compared with repeated assessment during exercise profoundly changed the nature of the relationship found between exercise and mood. Studies measuring mood before exercise, and again after exercise has ended and the person has recovered, generally report positive affective responses. However, Hall and colleagues’ data clearly show considerable mood deterioration as exercise intensity increases, with mood rising to more positive levels only on exercise completion. A City Guide To Ezhou 2016.