Effect of Fatigue and Active Hyperthermia on Proprioception

Abstract

PURPOSE: Proprioception is of paramount importance for motor control, with any alterations likely to alter sport performance and injury risk. Passive hyperthermia impairs proprioceptive acuity, but the effect of exercise-induced fatigue and active hyperthermia remain unclear. This study sought to determine the effect of a 30-min running time- trial in temperate and hot environments on proprioception. METHODS: Post familiarization, 11 trained runners (maximal aerobic velocity range 18 - 21.3 km.h-1) completed two 30-min running time-trials (TT) in temperate (CON, 22°C) and hot (HOT, 39°C) conditions on separate days in a counterbalanced manner. Proprioception was evaluated immediately pre- and post-TT by Active Movement Extent Discrimination Apparatus (AMEDA). Thermoregulatory [rectal (Tr) and skin temperature (Tsk)], physiological [heart rate (HR)] and perceptual [thermal comfort (TC)] responses were recorded. Data were compared via a two-way ANOVA for repeated measures. RESULTS: Tr, Tsk, HR and TC increased with exercise but reached higher values in HOT compared to CON (see Table 1, p<0.05). The average error for active movement discrimination displayed an interaction effect (p=0.029) with post-hoc analyses revealing that proprioception was impaired by running in HOT (p=0.028) but not in CON (p=0.547). CONCLUSION: Exercise-induced fatigue in HOT (but not CON) impaired proprioception and thus active hyperthermia may influence performance and injury risk during dynamic tasks requiring proprioceptive acuity.Table 1: Thermoregulatory, physiological and perceptual responses