The cytokine response to physical activity and training

Cytokines are soluble glycoproteins that are produced by and mediate commun ication between and within immune and nonimmune cells, organs and organ sys tems throughout the body. Pro- and anti-inflammatory mediators constitute t he inflammatory cytokines, which are modulated by various stimuli, includin g physical activity, trauma and infection. Physical activity affects local and systemic cytokine production at different levels, often exhibiting stri king similarity to the cytokine response to trauma and infection. The present review examines the cytokine response to short term exercise st ress. with an emphasis on the balance between pro- and anti-inflammatory me chanisms and modulation of both innate and specific immune parameters throu gh cytokine regulation. The effects of long term exercise on cytokine respo nses and the possible impact on various facets of the immune system are als o discussed, with reference to both cross-sectional and longitudinal studie s of exercise training. Finally, the validity of using exercise as a model for trauma and sepsis is scrutinised in the light of physiological changes, symptomatology and outcome, and limitations of the model are addressed. Further studies, examining the effect of exercise, trauma and infection on novel cytokines and cytokine systems are needed to elucidate the significan ce of cytokine regulation by physical activity and, more importantly, to cl arify the health implications of short and long term physical activity with respect to overall immune function and resistance to infection.