A great ally to beat stress is sport. In principle it is logical, if we consider stress as a primal defense mechanism in a fight-flight response, the carrying out of an important physical activity can be a way of disabling this response. This mechanism predisposes us for intense physical activity and once made under normal conditions, it is assumed that if the threat has disappeared this response should be removed. It may be that among other mechanisms this disconnect is due to the mediation of endorphins, some opiates secreted by the brain when doing sport, and that can generate a sense of relaxation and well-being to counteract the stress response, if the stimulus that caused it isn’t already present, bringing the body back to the previous normal state to the presence of the threat.
Another way in which the sport counteracts stress, is in cellular aging. In a study on the effect of exercise in people with chronic stress, telomere length was measured in people with this chronic stress and its effect was measured and found to effectively shortening of telomeres occurred. What was found is that people who took the recommended amount of daily exercise didn’t suffered the effect of telomere shortening. So, according to this study, exercise improved telomere length. Actually there are many studies on the association of physical activity and telomere length is clearly defined and that the greater sporting activity the longest telomere length.
 The power of exercise: buffering the effect of chronic stress on telomere length.
Eli Puterman,1,* Jue Lin,2 Elizabeth Blackburn,2 Aoife O’Donovan,1,3 Nancy Adler,1 and Elissa Epel1