VENTILATORY RESPONSE AT THE ONSET OF VOLUNTARY EXERCISE AND PASSIVE MOVEMENT IN ENDURANCE RUNNERS

The present study was performed to examine whether or not the ventilat ory response at the onset of voluntary exercise and passive movement i n endurance runners is the same as in untrained subjects. Twelve long- distance runners belonging to the varsity athletic club and 13 untrain ed subjects of our university participated as subjects in this study. Maximum oxygen uptake was significantly higher in the endurance runner group [mean (SD) 70.8 (4.7) ml . kg(-1) . min(-1)] than in the untrai ned group [49.8 (6.3) ml . kg(-1) . min(-1)]. Cardiorespiratory respon ses during voluntary exercise and passive movement of alternate flexio n-extension of the right and left legs for about 15 s at a frequency o f about 60 rpm, were determined by means of breath-by-breath technique s. Minute inspiratory ventilation (VI), tidal volume (V-T), respirator y frequency (f(b)), cardiac output ((Q) over dot (c)), stroke volume ( SV) and heart rate (HR) increased significantly immediately at the ons et of voluntary exercise and passive movement. The incremental rate fo r (V) over dot (1) was greater than that for (Q) over dot (c). Average values and standard deviations of changes in (V) over dot (1) were ca lculated as the difference between the mean of the first and second br eath and the mean of five breaths preceding the exercise or movement. The rates obtained in voluntary exercise and passive movement in the e ndurance runner group [2.34 (0.82) and 1.72 (0.71 1 . min(-1)), respec tively] were significantly (P < 0.05) lower than those in the untraine d group [4.16 (2.66) and 2.71 (1.56 1 . min(-1)), respectively]. Also changes in VT and HR were significantly lower in the endurance group t han in the untrained group with regard to both voluntary exercise and passive movement. The results suggest that the magnitude of cardioresp iratory responses at the onset of voluntary exercise and passive movem ent in humans is influenced by chronic endurance training for long per iods.