A comparison of respiratory compensation thresholds of anaerobic competitors, aerobic competitors and untrained subjects

This study compared respiratory compensation thresholds (RCT) ((V) over dot CO2 inflection point) of competitors in highly aerobic events (aerobic competitors, ARC) (n=16), competitors in highly anaerobic events (anaerobic competitors, ANC) (n=15), and untrained subjects (UT) (n=25). Maximal oxygen consumption ((V) over dot O-2max), respiratory compensation threshold as a percentage of (V) over dot O-2max (RCT), and (V) over dot O-2 at RCT ((V) over dot O-2RCT) were determined during a maximal Bruce treadmill protocol. (V) over dot O-2max (ml kg(-1) min(-1)) was significantly greater (P<0.05) for ARC [67.2 (8.5)] than for ANC [50.0 (7.8)] and UT [43.8 (5.4)]. However, the difference between ANC and UT only approached significance (P=0.07). RCT was not significantly different between ARC [76.3 (8.7)] and ANC [80.7 (6.8)] but was significantly lower (P<0.05) for UT [62.5 (8.8)]. (V) over dot O-2RCT (ml kg(-1) min(-1)) was significantly greater (P<0.05) for ARC [51.6 (11.0)] and ANC [40.2 (6.6)] than for UT [27.4 (5.4)], with a significant difference also between ARC and ANC. While used as a criterion for group assignment, greater (V) over dot O-2max, as well as RCT values in ARC (vs UT), reflect chronic aerobic training adaptations. ANC demonstrated (V) over dot O-2max values intermediate to ARC and UT, with RCT very comparable to those found in ARC. The results suggest subjects competitive in highly anaerobic events do not possess excessively high (V) over dot O-2max values. These individuals, however, demonstrate a high RCT when values are expressed relative to (V) over dot O-2max. Oxygen consumption at the RCT in this group is superior to that in UT but inferior to that in ARC, which likely has important implications regarding performance.