Effect of body temperature on ventilatory transients at start and end of exercise in man

Abstract

Ventilatory changes occurring within the first two breaths of the start (ON) or end (OFF) of work at various loads were studied in three healthy subjects at normal, and at elevated (+ 1.4°C) body temperature. The latter part of the study was carried out in a climatic chamber. In one subject both ON- and OFF-changes in minute ventilation were regularly greatest at the high temperature, while no significant differences between the two temperature levels were found in the other subjects. Neither steady state ventilation at equal loads nor the relative proportion of the rapid ONresponse to the steady state ventilation were different in the two conditions. A consistent finding in all three subjects was a marked overshoot of respiratory frequency in the first breath of work at high body temperature. Hyperthermia is hardly an important independent respiratory stimulus during muscular exercise. The neural stimulus at the start of work may, however, interact with the respiratory centers at elevated body temperature.