Department of Neurological, Neuropsychological, Morphological and Motor Sciences, School of Exercise and Sport Sciences, University of Verona, Via Felice Casorati, 43, 37131 Verona, Italy.
Eur J Appl Physiol. 2011 Jul;111(7):1517-27. doi: 10.1007/s00421-010-1786-y. Epub 2010 Dec 29.
VO₂, Q and muscular deoxyhaemoglobin (HHb) kinetics were determined in 14 healthy male subjects at the onset of constant-load cycling exercise performed at 80% of the ventilatory threshold (80%(VT)) and at 120% of VO₂max (120%(Wmax)). An innovative approach was applied to calculate the time constant (τ₂) of the primary phase of VO₂ and Q kinetics at 120%(Wmax). Data were linearly interpolated after a semilogarithmic transformation of the difference between required/steady state and measured values. Furthermore, VO₂, Q and HHb data were fitted with traditional exponential models. τ₂ of VO₂ kinetics was longer (62.5 ± 20.9 s) at 120%(Wmax) than at 80%(VT) (27.8 ± 10.4 s). The τ₂ of Q kinetics was unaffected by exercise intensity and, at 120% of VO₂max, it was significantly faster (τ₂ = 35.7 ± 28.4 s) than that of VO₂ response. The time delay of HHb kinetics was shorter (4.3 ± 1.7 s) at 120%(Wmax) than at 80%(VT) (8.5 ± 2.6 s) suggesting a larger mismatch between O₂ uptake and delivery at 120%(Wmax). These results suggest that VO₂ at the onset of exercise is not regulated/limited by muscle's O₂ utilisation and that a slower adaptation of capillary perfusion may cause the deceleration of VO₂ kinetics observed during supramaximal exercise.
在 14 名健康男性受试者中，在以 80%通气阈（80%（VT））和 120%最大摄氧量（120%（Wmax））进行的恒负荷踏车运动开始时，测定了 VO₂、Q 和肌肉脱氧血红蛋白（HHb）动力学。应用一种创新方法来计算 120%（Wmax）时 VO₂和 Q 动力学的主要阶段的时间常数（τ₂）。在所需/稳态和测量值之间的差值的半对数转换之后，数据进行线性内插。此外，VO₂、Q 和 HHb 数据拟合传统指数模型。在 120%（Wmax）时，VO₂动力学的 τ₂较长（62.5±20.9 s），而在 80%（VT）时较短（27.8±10.4 s）。Q 动力学的 τ₂不受运动强度的影响，在 120%的 VO₂max 时，它明显快于 VO₂反应（τ₂=35.7±28.4 s）。HHb 动力学的时间延迟在 120%（Wmax）时较短（4.3±1.7 s），而在 80%（VT）时较长（8.5±2.6 s），表明在 120%（Wmax）时，O₂摄取和输送之间的不匹配较大。这些结果表明，运动开始时的 VO₂不受肌肉 O₂利用的调节/限制，毛细血管灌注的适应性较慢可能导致在最大运动期间观察到的 VO₂动力学减速。
