Psychosocial stress is a natural response that occurs in the human body when a problem arises that an individual feels they may not be able to resolve or they perceive themselves to be ‘out of their depth’. The body responds to this stressful situation by releasing hormones such as cortisol and epinephrine (also known as adrenaline, causes an increase in heart rate). Cortisol is a hormone produced in the adrenal glands of the body and is the primary hormone responsible for the stress response. The hypothalamic-pituitary-adrenal axis (HPA) is a complex set of feedback loops that essentially controls certain hormone release – one of which is cortisol. While well regulated levels of cortisol ensure certain processes such as gluconeogenesis (formation of glucose in the liver) take place, it has been suggested that stress induced cortisol release may result in weight gain [with lean women being possibly more susceptible] (Epel et al. 2000). Furthermore psychosocial stress [and the subsequent cortisol release] have been shown to increase the risk of diseases such as hypertension or depression (Rimmele et al. 2009). Stress is an unavoidable response that the human body delivers but a study conducted by Rimmele et al. (2007) indicated that it was possible to reduce the level of this stress response.
For a lot of people exercise is a habit, for some it’s a hard fought struggle to lose extra weight but for everyone it is one of the best ways to reduce stress in their life. Exercise is known to have a positive impact on depression, anxiety (Salmon. 2001) and as importantly, stress (Rimmele et al. 2009). A study by Rimmele et al. (2007) found that untrained (less than 2 hours of exercise per week) men displayed a greater stress response than elite sportsmen. This was shown by a significantly greater level of cortisol in the untrained men following a stress test. Similarly the lower levels of cortisol found in the elite sportsmen indicates that they had a lesser stress response to the test. While this may be partially due to the elite sportsmen’s familiarity to demanding or worrying situations (media coverage, large crowds of spectators etc.) it was also found that trained (greater than 5 hours of training a week) men exhibited a stress response in between that of untrained and elite sportsmen.
The levels of cortisol released in the trained men following the stress test were not found to be significantly different to that of untrained men, however the heart rate responses were significantly different. So despite the level of cortisol release being no different to that of untrained men, trained men exhibited a reduced heart rate response, indicating a lesser stress response to the test. Rimmele et al. (2007) suggest that the disassociation between the heart rate and the cortisol response found in the trained men may have occurred due to the HPA being less sensitive to the ‘adaptive consequences of physical activity’. This implies that the HPA may take longer to adapt to the benefits of physical activity (hence the decreased levels of cortisol found in elite sportsmen and not the trained men).
The results of the study suggest that varying levels of physical activity will affect the human body’s response to psychosocial stress. So, while it is well known that exercise is an effective method for stress reduction, it should also be recognised the extent to which it can help if the right volume of exercise is completed. A reduction in psychosocial stress may not only improve quality of life through increased happiness [due to a reduction in stress] but also by decreasing susceptibility to diseases such as hypertension or depression.
Epel, E. S., et al. 2000. Stress and body shape: stress-induced cortisol secretion is consistently greater among women with central fat. Psychosom Med. 62(5): pp.623-632.
Rimmele, U., et al. 2007. Trained men show lower cortisol, heart rate and psychological responses to psychosocial stress compared with untrained men. Psychoneuroendocrinology. 32(1): pp.627-635.
Rimmele, U., et al. 2009. The level of physical activity affects adrenal and cardiovascular reactivity to psychosocial stress. Psychoneuroendocrinology. 34(1): pp.190-198.
Salmon, P. 2001. Effects of physical exercise on anxiety, depression and sensitivity to stress: a unifying theory. Clinical Psychology Review. 21(1): pp.33-61.
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About Scott Findlay
Sports science graduate from Scotland. Aspiring PhD student and professional triathlete.