Jones Andrew M, Fulford Jonathan, Wilkerson Daryl P
School of Sport and Health Sciences, St Luke's Campus, University of Exeter, Heavitree Road, Exeter, UK.
Exp Physiol. 2008 Apr;93(4):468-78. doi: 10.1113/expphysiol.2007.041897. Epub 2008 Feb 1.
(31)Phosphate-magnetic resonance spectroscopy and near infrared spectroscopy (NIRS) were used for the simultaneous assessment of changes in quadriceps muscle metabolism and oxygenation during consecutive bouts of high-intensity exercise. Six male subjects completed two 6 min bouts of single-legged knee-extension exercise at 80% of the peak work rate separated by 6 min of rest while positioned inside the bore of a 1.5 T superconducting magnet. The total haemoglobin and oxyhaemoglobin concentrations in the area of the quadriceps muscle interrogated with NIRS were significantly higher in the baseline period prior to the second compared with the first exercise bout, consistent with an enhanced muscle oxygenation. Intramuscular phosphorylcreatine concentration ([PCr]) dynamics were not different over the fundamental region of the response (time constant for bout 1, 51 +/- 15 s versus bout 2, 52 +/- 17 s). However, the [PCr] dynamics over the entire response were faster in the second bout (mean response time for bout 1, 72 +/- 16 s versus bout 2, 57 +/- 8 s; P < 0.05), as a consequence of a greater fall in [PCr] in the fundamental phase and a reduction in the magnitude of the 'slow component' in [PCr] beyond 3 min of exercise (bout 1, 10 +/- 6% versus bout 2, 5 +/- 3%; P < 0.05). These data suggest that the increased muscle O(2) availability afforded by the performance of a prior bout of high-intensity exercise does not significantly alter the kinetics of [PCr] hydrolysis at the onset of a subsequent bout of high-intensity exercise. The greater fall in [PCr] over the fundamental phase of the response following prior high-intensity exercise indicates that residual fatigue acutely reduces muscle efficiency.
（31）采用磷磁共振波谱和近红外光谱（NIRS）同时评估连续高强度运动期间股四头肌代谢和氧合的变化。六名男性受试者在1.5T超导磁体的磁孔内，以峰值工作率的80%完成了两组6分钟的单腿伸膝运动，每组运动之间休息6分钟。与第一次运动回合相比，第二次运动回合前基线期用NIRS检测的股四头肌区域的总血红蛋白和氧合血红蛋白浓度显著更高，这与肌肉氧合增强一致。在反应的基本区域内，肌内磷酸肌酸浓度（[PCr]）动态没有差异（第一回合的时间常数为51±15秒，第二回合为52±17秒）。然而，由于在基本阶段[PCr]下降幅度更大，且运动3分钟后[PCr]“慢成分”的幅度减小（第一回合为10±6%，第二回合为5±3%；P<0.05），第二回合中整个反应过程的[PCr]动态更快（第一回合的平均反应时间为72±16秒，第二回合为57±8秒；P<0.05）。这些数据表明，先前高强度运动所带来的肌肉O₂可用性增加，并不会显著改变随后高强度运动开始时[PCr]水解的动力学。先前高强度运动后反应基本阶段[PCr]下降幅度更大，表明残余疲劳会急性降低肌肉效率。
