V̇O ₂ response at the onset of heavy exercise is accelerated not by diathermic warming of the thigh muscles but by prior heavy exercise

We investigated whether the elevated muscle temperature induced by the first bout influenced V̇O ₂ the response during a second-bout of heavy exercise. The control conditions were two consecutive 6-min leg cycling bouts (work rate: δ50% between LT and V̇O ₂ max) separated by a 6-min baseline at 20 W (L1-ex to L2-ex). In the experimental conditions prior to the main bout (H2-ex), the diathermic warming to the front thigh was substituted for the first-bout. The V̇O ₂ response for the second bout was significantly accelerated compared with the first bout (mean ± SD of the τ by monoexponential fitting: L1-ex: 53.8 ± 11.6, L2-ex: 38.7 ± 7.9 s, P < 0.05). The diathermic warm-up, however, could not accelerate response for subsequent supra-LT leg exercise (τ for H2-ex: 52.3 ± 7.7 s). It was concluded that the facilitation of V̇O ₂ response during supra-LT exercise after prior heavy exercise does not seem to be caused by increased muscle temperature per se and its related factors.