Entrainment of breathing in cyclists and non-cyclists during arm and leg exercise

The purpose of this study was to compare the incidence of entrainment of breathing (ENT) between cyclists (C; n=8) and non-cyclists (NC; n=8) during leg cycling (LC) and arm cycling (AC). No subjects were training regularly in upper body endurance exercise. Day 1 consisted of spirometry and a VO2max test on both an arm and leg ergometer in random order separated by at least 60 min. On Day 2, subjects performed both AC and LC exercise with each session consisting of 5 min of warm-up at 20% and three consecutive 6 min loads at 40%, 60%, and 80% of task specific peak power output (WL1, WL2, WL3, respectively). Sessions were separated by at least 45 min. The final 3 min of each load were analyzed for entrainment of pedal and breathing frequencies using integer and half-integer ratios. A total of six subjects were unable to complete at least one exercise session at WL3 and therefore this load was excluded from analysis. Mean % VO2max during exercise was not different between cyclists and controls with respect to intensity and mode (AC= approximately 50% and 70%; LC= approximately 55% and 75% at WL1 and WL2, respectively). A repeated measures ANOVA revealed no effect on incidence of entrainment (%ENT) by group, mode of exercise, or exercise intensity (p=0.12, 0.24, and 0.88, respectively). %ENT was highest in cyclists during leg exercise (cyclists: LC=32%; AC=19%; controls: LC=18%; AC=21%) however this difference was not significant (p=0.07). In all situations that would be considered unfamiliar for both groups %ENT was similar. These results suggest that during cycling exercise at intensities of 75% VO2max or less, regular training may result in higher %ENT and that ENT is not transferable to an unfamiliar mode of exercise using different muscle groups.