Endurance performances across a spectrum of distances, as well as individuals performing occupational duties, are markedly impaired by heat stress (Guy et al., 2014). In particular, reductions in endurance cycling performances are observed as environmental temperatures are elevated to, or exceed 30ºC (Racinais et al., 2015). Whereas, a diminished work capacity in uncompensable conditions is observed in firefighters and military soldiers, while wearing personal protective clothing (Montain et al., 1994; Eglin, 2007).
There are numerous contributing factors which lead to heat related illnesses and an increased inflammatory response, these include, but are not limited to; unsuccessful preparation, diverse biophysical characteristics, age, aerobic capacity, large rises in core temperature, ineffective sudomotor responses, insufficient rest and increased circulating stress hormones (Epstein, 1990; Epstein et al., 1999; Sawka et al., 2011). It has been suggested that a single predisposing phenotypic characteristic, heat acclimation state, may explain the vast inter-individual response to thermally stressful environments, and may categorise those who are more susceptible to HRI (Havenith, 1997; Heled et al., 2004).
This research is investigating the effects of acute and chronic heat acclimation on inflammatory responses, aerobic capacity and heat acclimation state. By investigating the effects of training frequency and physiological responses to heat stress, through once and twice daily heat acclimation protocols and subsequently exercise tolerance, we can identify factors which determine the vast array of heat acclimation states and individual responses to heat stress. This will enable us to individually prescribe optimal heat acclimation for athletes and occupational personnel preparing to exercise performances or work duties, while reducing the likelihood of heat related illness.