The purpose of this study was to evaluate the acute responses of tidal volume (TV), respiratory rate (RR) and ventilation (VE) to incremental cycle ergometery (CE) and treadmill(TM) exercise in trained athletes. Triathletes (N=16, 10 male, 6 female) underwent VO2max testing on CE and TM. Breakpoints were analyzed with a macro designed to select breakpoints by the least squared error method, and slope significance assessed by linear regression ANOVA. VE max was significantly greater for CE (157.5±29.4 vs. 145.7±27.5 l/min, CE vs. TM, respectively). The greater VE for CE was the result of a greater RR for CE (51.7±6.7 vs. 48.3±5.7 breaths/min CE vs. TM, respectively) . For both CE and TM testing VE and RR were significantly correlated to VO2max. TVmax was unrelated to VO2max for both CE and TM. TV response patterns were highly variable, with 37.5% of subjects displaying either a plateau or downward deflection at breakpoint and 62.5% displaying either a linear or upward deflection at breakpoint. Chi square analysis indicated no difference in response pattern between CE and TM, and TV response was not related to VO2max. In subjects displaying a breakpoint or downward deflection in TV, RR increased exponentially to facilitate an increase in VE. The ability to ventilate large volumes of air at maximal exercise is important in attaining high VO2max values. However, neither TVmax nor the TV pattern appears important in attaining high VO2max values. ABSTRACT FROM AUTHOR
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