Gray Stuart R, Söderlund Karin, Ferguson Richard A
Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK.
J Sports Sci. 2008 May;26(7):701-7. doi: 10.1080/02640410701744438.
In this study, we examined the effect of muscle temperature (Tm) on adenosine triphosphate (ATP) and phosphocreatine utilization in single muscle fibres during the development of maximal power output in humans. Six male participants performed a 6-s maximal sprint on a friction-braked cycle ergometer under both normal (Tm = 34.3 degrees C, s = 0.6) and elevated (T(m) = 37.3 degrees C, s = 0.2) muscle temperature conditions. During the elevated condition, muscle temperature of the legs was raised, passively, by hot water immersion followed by wrapping in electrically heated blankets. Muscle biopsies were taken from the vastus lateralis before and immediately after exercise. Freeze-dried single fibres were dissected, characterized according to myosin heavy chain composition, and analysed for ATP and phosphocreatine content. Single fibres were classified as: type I, IIA, IIAX25 (1 - 25% IIX isoform), IIAX50 (26 - 50% IIX), IIAX75 (51 - 75% IIX), or IIAX100 (76 - 100% IIX). Maximal power output and pedal rate were both greater (P < 0.05) during the elevated condition by 258 W (s = 110) and 22 rev . min(-1) (s = 6), respectively. In both conditions, phosphocreatine content decreased significantly in all fibre types, with a greater decrease during the elevated condition in type IIA fibres (P < 0.01). Adenosine triphosphate content was also reduced to a greater (P < 0.01) extent in type IIA fibres during the elevated condition. The results of the present study indicate that after passive elevation of muscle temperature, there was a greater decrease in ATP and phosphocreatine content in type IIA fibres than in the normal trial, which contributed to the higher maximal power output.
在本研究中，我们检测了人体在产生最大功率输出的过程中，肌肉温度（Tm）对单根肌纤维中三磷酸腺苷（ATP）和磷酸肌酸利用情况的影响。六名男性参与者在摩擦制动式自行车测力计上进行了6秒的最大冲刺，分别处于正常（Tm = 34.3摄氏度，标准差 = 0.6）和升高（Tm = 37.3摄氏度，标准差 = 0.2）的肌肉温度条件下。在升高温度的条件下，通过热水浸泡使腿部肌肉温度被动升高，随后用电动加热毯包裹。在运动前和运动后立即从股外侧肌取肌肉活检样本。将冻干的单根肌纤维分离出来，根据肌球蛋白重链组成进行分类，并分析其ATP和磷酸肌酸含量。单根肌纤维分为：I型、IIA型、IIAX25（1 - 25% IIX亚型）、IIAX50（26 - 50% IIX）、IIAX75（51 - 75% IIX）或IIAX100（76 - 100% IIX）。在升高温度的条件下，最大功率输出和踏频均更高（P < 0.05），分别提高了258瓦（标准差 = 110）和22转·分钟−1（标准差 = 6）。在两种条件下，所有纤维类型中的磷酸肌酸含量均显著下降，其中IIA型纤维在升高温度条件下下降幅度更大（P < 0.01）。在升高温度条件下，IIA型纤维中的三磷酸腺苷含量也有更大程度的降低（P < 0.01）。本研究结果表明，在肌肉温度被动升高后，IIA型纤维中ATP和磷酸肌酸含量的下降幅度比正常试验时更大，这促成了更高的最大功率输出。
