The effect of pedal rate on pulmonary O2 uptake kinetics during very heavy intensity exercise in trained and untrained teenage boys

This study tested the hypothesis that the V˙O2 kinetic response would be slowed in untrained (UT) but not trained (T) teenage participants whilst cycling at 115 rev min−1 compared to 50 rev min−1. Eight UT and seven T boys completed two square-wave transitions to very heavy-intensity exercise pedalling at 50 rev min−1 and 115 rev min−1. In UT at the higher pedal rate, the phase II V˙O2τ was significantly (P < 0.01) slower (50 rev min−1: 32 ± 5 vs. 115 rev min−1: 42 ± 11 s) and the relative V˙O2 slow component was significantly (P < 0.01) elevated (50 rev min−1: 10 ± 3 vs. 115 rev min−1: 16 ± 5%). The phase II V˙O2τ (50 rev min−1: 26 ± 4 vs. 115 rev min−1: 22 ± 6 s) and relative V˙O2 slow component (50 rev min−1: 14 ± 5 vs. 115 rev min−1: 17 ± 3%) were unaltered by pedal rate in T (P > 0.05). These data are consistent with the notion that V˙O2 kinetics are influenced by muscle fibre recruitment in youth but this effect is attenuated in endurance trained teenage boys.