Comparison of hyperthermic hyperpnea elicited during rest and submaximal, moderate-intensity exercise
- 1 April 2008
- journal article
- Published by American Physiological Society in Journal of Applied Physiology
- Vol. 104 (4), 998-1005
- https://doi.org/10.1152/japplphysiol.00146.2007
Abstract
We tested the hypothesis that, in humans, hyperthermic hyperpnea elicited in resting subjects differs from that elicited during submaximal, moderate-intensity exercise. In the rest trial, hot-water legs-only immersion and a water-perfused suit were used to increase esophageal temperature (Tes) in 19 healthy male subjects; in the exercise trial, Tes was increased by prolonged submaximal cycling [50% peak O2 uptake (V̇o2)] in the heat (35°C). Minute ventilation (V̇e), ventilatory equivalent for V̇o2 (V̇e/V̇o2) and CO2 output (V̇e/V̇co2), tidal volume (Vt), and respiratory frequency (f) were plotted as functions of Tes. In the exercise trial, V̇e increased linearly with increases (from 37.0 to 38.7°C) in Tes in all subjects; in the rest trial, 14 of the 19 subjects showed a Tes threshold for hyperpnea (37.8 ± 0.5°C). Above the threshold for hyperpnea, the slope of the regression line relating V̇e and Tes was significantly greater for the rest than the exercise trial. Moreover, the slopes of the regression lines relating V̇e/V̇o2, V̇e/V̇co2, and Tes were significantly greater for the rest than the exercise trial. The increase in V̇e reflected increases in Vt and f in the rest trial, but only f in the exercise trial, after an initial increase in ventilation due to Vt. Finally, the slope of the regression line relating Tes and Vt or f was significantly greater for the rest than the exercise trial. These findings indicate that hyperthermic hyperpnea does indeed differ, depending on whether one is at rest or exercising at submaximal, moderate intensity.Keywords
This publication has 25 references indexed in Scilit:
- Components and mechanisms of thermal hyperpneaJournal of Applied Physiology, 2006
- Mechanisms for the control of respiratory evaporative heat loss in panting animalsJournal of Applied Physiology, 2006
- Relationship between ventilatory response and body temperature during prolonged submaximal exerciseJournal of Applied Physiology, 2006
- Middle cerebral artery blood velocity is reduced with hyperthermia during prolonged exercise in humansThe Journal of Physiology, 2001
- Core temperature thresholds for hyperpnea during passive hyperthermia in humansEuropean Journal of Applied Physiology, 1995
- The role of spinal thermosensitive structures in the respiratory heat loss during exercisePflügers Archiv - European Journal of Physiology, 1974
- Effect of Body Temperature on Steady State Ventilation and Metabolism in ExerciseActa Physiologica Scandinavica, 1973
- Changes in respiratory activity and body temperature of the severely heat-stressed ox and sheepComparative Biochemistry and Physiology, 1969
- Effects of various respiratory stimuli on the depth and frequency of breathing in manRespiration Physiology, 1966
- The Influence of High Air Temperatures No. IEpidemiology and Infection, 1905