Effect of acute ambient temperature exposure on cardio-pulmonary and respiratory kinetics in men

Purpose: The goal of the study was to compare the kinetics responses of heart rate (HR) and pulmonary (V’O2pulm) and muscular (V’O2musc) oxygen uptake during dynamic leg exercise across different acute ambient temperature conditions in a climatic chamber.
Methods: Thirteen physically healthy, active male volunteers performed pseudo-random binary sequence (PRBS) work rate (WR) changes between 30 W and 80 W at 15°C, 25°C and 35°C, respectively. HR was measured beat-to-beat by echocardiogram and V’O2pulm by breath-by-breath gas exchange, and V’O2musc estimations were assessed by applying a circulatory model and cross-correlation functions based on the approach of Hoffmann et al. (2013).
Results: No significant differences were identified across the various temperature conditions in each case for HR, V’O2pulm, or V’O2musc kinetics (p > 0.05). Baroreflex regulation based on HR kinetics does not seem to be influenced between ambient temperatures of 15°C and 35°C during dynamic exercise.
Conclusions: The results imply that ambient temperatures of 15°C, 25°C and 35°C have no effect on HR, V’O2pulm or V’O2musc kinetics during dynamic moderate exercise. The applied approach may be of interest for assessments of the cardio-pulmonary and respiratory health statuses of individuals working or performing sports in extreme temperature environments. Furthermore, differentiation between systemic (e.g., cardio-dynamic: HR) and specific (e.g., exercising tissues: V’O2musc) determinants of the relevant physiological systems may improve the evaluation of an individual’s health status.