Effect of External Cues for Pedal Pacing on Breathing Pattern during Cycle Exercise

Abstract

Fourteen subjects performed cycle exercise at work loads of 0 and 1 kp, each for 3 min, during which the pedal rate was kept constant by various external cues. Six cues were used in order: no cue (Ni), a speedometer dial (S), a flashing light (F), a verbal command (V), a metronome sound (M) and no cue, again (N2). An attempt was to study the effect of these cues on breathing pattern in a lower tidel volume (V_T) range during exercise, actually V_T increasing to 2 times the resting levels. In N1 and N2, exercise was performed at preferred pedal rates, which were 40±4 (mean±S.E.)rpm and 52±2 rpm, respectively. Pedaling to other four cues was kept at 50 rpm. Ventilatory responses during exercise were similar in all conditions of cue except N1. Increases in respiratory frequency (f) during exercise were similar in S but greater in F at 0-kp load and in V and M at 1-kp load, compared with N2. The greater increases in fin F, V and M were due to greater shortening in inspiratory (T_I) and expiratory (T_E) durations. In any conditions of cue, T_I and T_E decreased with increasing V_T in response to exercise. The present study indicates that (1) breathing pattern during rhythmic exercise is affected by external rhythmic stimuli like F, V and M, and (2) there is no such a V_T range that T_I and T_E remain constant in the V_T-T_I, and V_T-T_E, relations during exercise.