Revisiting Ventilatory and Cardiovascular Predictions of Whole-Body Metabolic Rate

Objective: The influence of variations in exercise mode, thermal state, and load carriage on cardiac and ventilatory predictors of metabolic rate were investigated. Methods: Fifteen males were studied at rest and during whole-, upper-, and lower-body exercise (unloaded and loaded) under thermoneutral and hot conditions. Results: Ventilatory predictions were superior in thermoneutral (residual mean square error range: 0.04 to 0.17 Lmin(-1) vs 0.21 to 0.36 Lmin(-1)) and hot conditions (0.03 to 0.07 Lmin(-1) vs 0.21 to 0.24 Lmin(-1)). Predictions derived from whole- or lower-body exercise, and unloaded or loaded exercise could be interchanged without significant error. Nevertheless, a mode-specific prediction was required for upper-body work, and mild hyperthermia significantly reduced the precision of cardiac predictions. Conclusion: Ventilatory predictions were more precise, but errors from heart-rate predictions could be minimized by using thermal-state and exercise mode-specific predictions.