Changes in respiration in the transition from heavy exercise to rest

Abstract

Transitions from rest to exercise and vice versa are reported to be associated with instantaneous changes in minute ventilation and the changes in the off-transitions are thought to be the reverses of those in the on-transitions. Such changes have been observed mainly in mild-moderate exercise and their extrapolation to heavy exercise above anaerobic threshold is unwarranted. Hence, the purpose of this study was to determine the changes in ventilation in the transition from heavy exercise above anaerobic threshold to rest. Five healthy volunteers ran on a motor-driven treadmill at a constant work-load corresponding to 80% VO2max and above anaerobic threshold. Changes in minute ventilation and end-tidal PCO2 in the on- and off-transitions were determined breath by breath by starting and stopping the treadmill abruptly. The results indicate that, contrary to what is reported for mild-moderate exercise, an instantaneous drop in ventilation is absent in the off-transition of heavy exercise above anaerobic threshold. The gradual decline in minute ventilation may be due to a sustained respiratory drive from a central neural reverberatory mechanism, blood-borne respiratory stimuli and/or a peripheral neurogenic drive originating in the so-called metaboloreceptors.

The relation between age and time to maximal bronchoconstriction following exercise in children

“…Moreover, children and adults may not have similar abilities in shortterm or exhaustive work when corrected for size. 24 It was previously reported that the decline in postexercise hyperventilation is related to the load and duration of the exercise, 25 while it was also found that the recovery time is a function of age. 26,27 Thus it is possible that the duration of post-exercise hyperventilation in younger children is shorter than in older children, leading to earlier release of mediators, followed by earlier bronchoconstriction.…”