Publication: Brain and cardiorespiratory responses to exercise in hot and thermoneutral conditions

Edwards, A.M., Deakin, G.B., and Guy, J.H. (2016) Brain and cardiorespiratory responses to exercise in hot and thermoneutral conditions. International Journal of Sports Medicine, 37 (10). pp. 779-784.

http://researchonline.jcu.edu.au/45850/

Abstract
The aim of this study was to test whether or not concurrent evaluations of brain (electroencephalography [EEG]) and cardiorespiratory responses to exercise are influenced by environmental conditions. 10 adult male participants performed a standardized incremental exercise test to exhaustion on a cycle ergometer in an environment controlled laboratory on 2 separate occasions, in a randomized order; one in a hot condition (34.5°C) and one in a thermoneutral condition (20°C). EEG, heart rate and expired air were collected throughout. EEG data were decontaminated for artefacts, log-transformed and expressed as aggregated alpha and beta power responses across electrodes reflecting the frontal cortex of the brain. Performance outcomes showed there was no difference in  V˙O₂ peak across hot (42.5 ml/kg/min) and neutral (42.8 ml/kg/min) conditions, although ventilatory threshold (V(T)) occurred at a lower threshold (68%) in hot compared to neutral condition (74%) (p<0.05). EEG alpha and beta wave responses both demonstrated significant increases from baseline to V(T) (p<0.01). EEG beta-band activity was significantly elevated in the heat compared to the neutral condition. In conclusion, elevated EEG beta-band activity in response to incremental exercise in the heat suggests that beta-band activation and cortical awareness increases as exercise becomes increasingly intense.