Blomstrand E, Essén-Gustavsson B
Department of Physiology III, Karolinska Institute, Stockholm, Sweden.
Acta Physiol Scand. 1987 Dec;131(4):569-74. doi: 10.1111/j.1748-1716.1987.tb08277.x.
Six male subjects performed intensive cycle exercise to exhaustion after cooling their legs in water at 10-12 degrees C (muscle temperature (Tm) 28 +/- 2.6 degrees C, mean +/- SD). Exercise at exactly the same rate and duration (370 +/- 34 W, 1.5 +/- 0.2 min) was then repeated by each subject 2-5 weeks later at normal Tm (35 +/- 1.0 degrees C). Muscle biopsies were taken from the vastus lateralis muscle at rest and after exercise. The muscle tissue was freeze-dried and fragments of single fibres were dissected out. The fibres were classified and pooled into groups of type I and type II. Analyses of glycogen, glucose 6-phosphate, lactate and phosphagens were performed on pools of type-identified fibres. After exercise at reduced Tm, all subjects had higher concentrations of glucose 6-phosphate and lactate in both type I and type II fibres, and in most subjects the concentrations of ATP and phosphocreatine were lower as compared with the findings after exercise at normal Tm. During exercise the glycogen content of both fibre types decreased to a greater extent at reduced than at normal Tm in most subjects. The results suggest that during intensive dynamic exercise at reduced Tm there is a higher degree of glycolysis from glycogen in the muscle than in the normal situation. In some subjects the cause of fatigue may be related to a more rapid accumulation of lactate in the cold muscle, while in others fatigue may be related to alternative factors, e.g. low levels of ATP and phosphocreatine.
六名男性受试者在将腿部置于10 - 12摄氏度的水中冷却后（肌肉温度（Tm）为28±2.6摄氏度，平均值±标准差）进行高强度自行车运动直至力竭。然后，在2 - 5周后，每位受试者在正常肌肉温度（35±1.0摄氏度）下以完全相同的速率和持续时间（370±34瓦，1.5±0.2分钟）重复进行运动。在休息和运动后从股外侧肌采集肌肉活检样本。将肌肉组织冻干并解剖出单根纤维的片段。对纤维进行分类并归为I型和II型组。对已鉴定类型的纤维组进行糖原、6 - 磷酸葡萄糖、乳酸和磷酸肌酸的分析。与在正常肌肉温度下运动后的结果相比，在降低肌肉温度后进行运动时，所有受试者的I型和II型纤维中的6 - 磷酸葡萄糖和乳酸浓度都更高，并且在大多数受试者中，ATP和磷酸肌酸的浓度更低。在运动过程中，大多数受试者的两种纤维类型的糖原含量在降低的肌肉温度下比在正常肌肉温度下下降幅度更大。结果表明，在降低的肌肉温度下进行高强度动态运动时，肌肉中糖原的糖酵解程度比正常情况更高。在一些受试者中，疲劳的原因可能与冷肌肉中乳酸的更快积累有关，而在另一些受试者中，疲劳可能与其他因素有关，例如ATP和磷酸肌酸水平较低。
