Heat shock factor activation in human muscles following a demanding intermittent exercise protocol is attenuated with hyperthermia

Abstract

[EN] Aim:The present study investigated whether increased activation of heatshock factors (HSF) following exercise relates primarily to the increasedmuscle temperature or to exercise in general.Methods:Six subjects completed 40 min of intermittent cycling (15s : 15sexercise:recovery at 300 22 W) at an ambient temperature of either20.0 1.3 or 40.3 0.7°C. Muscle biopsies were taken prior to andimmediately following the exercise protocol with samples analysed for HSFDNA binding by electrophoretic mobility shift assay.Results:Exercise at 40°C resulted in significantly increased oesophageal(39.3 0.2°C) and muscle temperature (40.0 0.2°C) at the end of theexercise protocol compared with 20°C (oesophageal, 38.1 0.1°C; mus-cle, 38.9 0.2°C). However, an increased DNA binding of HSF was notevident following exercise at 40°C (reduced by 21 22%) whereas itincreased by 29 51% following exercise at 20°C.Conclusion:It appears that increased temperature is not the major factorresponsible for activation of HSF DNA binding.