Jones Andrew M, Carter Helen, Pringle Jamie S M, Campbell Iain T
Department of Exercise and Sport Science, Manchester Metropolitan University, Alsager ST7 2HL, United Kingdom.
J Appl Physiol (1985). 2002 Jun;92(6):2571-7. doi: 10.1152/japplphysiol.01065.2001.
The purpose of this study was to test the effect of oral creatine (Cr) supplementation on pulmonary oxygen uptake (VO(2)) kinetics during moderate [below ventilatory threshold (VT)] and heavy (above VT) submaximal cycle exercise. Nine subjects (7 men; means +/- SD: age 28 +/- 3 yr, body mass 73.2 +/- 5.6 kg, maximal VO(2) 46.4 +/- 8.0 ml. kg(-1). min(-1)) volunteered to participate in this study. Subjects performed transitions of 6-min duration from unloaded cycling to moderate (80% VT; 8-12 repeats) and heavy exercise (50% change; i.e., halfway between VT and maximal VO(2); 4-6 repeats), both in the control condition and after Cr loading, in a crossover design. The Cr loading regimen involved oral consumption of 20 g/day of Cr monohydrate for 5 days, followed by a maintenance dose of 5 g/day thereafter. VO(2) was measured breath by breath and modeled by using two (moderate) or three (heavy) exponential terms. For moderate exercise, there were no differences in the parameters of the VO(2) kinetic response between control and Cr-loaded conditions. For heavy exercise, the time-based parameters of the VO(2) response were unchanged, but the amplitude of the primary component was significantly reduced with Cr loading (means +/- SE: control 2.00 +/- 0.12 l/min; Cr loaded 1.92 +/- 0.10 l/min; P < 0.05) as was the end-exercise VO(2) (control 2.19 +/- 0.13 l/min; Cr loaded 2.12 +/- 0.14 l/min; P < 0.05). The magnitude of the reduction in submaximal VO(2) with Cr loading was significantly correlated with the percentage of type II fibers in the vastus lateralis (r = 0.87; P < 0.01; n = 7), indicating that the effect might be related to changes in motor unit recruitment patterns or the volume of muscle activated.
本研究的目的是测试口服肌酸（Cr）补充剂对中等强度[低于通气阈值（VT）]和高强度（高于VT）次最大强度循环运动期间肺氧摄取（VO₂）动力学的影响。九名受试者（7名男性；平均值±标准差：年龄28±3岁，体重73.2±5.6 kg，最大VO₂ 46.4±8.0 ml·kg⁻¹·min⁻¹）自愿参与本研究。受试者在对照条件下以及Cr负荷后，采用交叉设计进行从无负荷骑行到中等强度运动（80%VT；8 - 12次重复）和高强度运动（50%变化；即VT与最大VO₂之间的中间值；4 - 6次重复）的6分钟时长转换。Cr负荷方案包括连续5天每天口服20克一水肌酸，之后维持剂量为每天5克。VO₂逐 breath 测量，并使用两个（中等强度）或三个（高强度）指数项进行建模。对于中等强度运动，对照和Cr负荷条件下VO₂动力学反应的参数没有差异。对于高强度运动，VO₂反应的基于时间的参数没有变化，但Cr负荷后主要成分的幅度显著降低（平均值±标准误：对照2.00±0.12 l/min；Cr负荷1.92±0.10 l/min；P < 0.05），运动结束时的VO₂也是如此（对照2.19±0.13 l/min；Cr负荷2.12±0.14 l/min；P < 0.05）。Cr负荷后次最大VO₂降低的幅度与股外侧肌中II型纤维的百分比显著相关（r = 0.87；P < 0.01；n = 7），表明这种影响可能与运动单位募集模式的变化或激活的肌肉量有关。
