Jansen R, Ament W, Verkerke G J, Hof A L
Department of Human Movement Sciences, University of Groningen, The Netherlands.
Eur J Appl Physiol Occup Physiol. 1997;75(2):102-8. doi: 10.1007/s004210050133.
The electromyogram (EMG) median power frequency of the vastus lateralis and flexor digitorum superficialis muscles was measured in 12 subjects during cycle ergometry with step-wise increasing exercise intensities up to 100% of VO2max. Blood lactate concentration was measured to investigate the relationship between changes in lactate concentration and shifts in the EMG median power frequency of exercising vastus lateralis and non-exercising flexor digitorum superficialis muscles. The results indicated that lactate concentration did not systematically affect median frequency: in spite of a considerable increase in blood lactate concentration, no systematic decrease of the median frequency during exercise was found, either for the vastus lateralis or for the flexor digitorum superficialis muscles. Instead of a decrease of the median frequency during exercise, as seen in isometrical protocols, an increase was seen in most subjects. An interesting finding was a decrease of the median frequency of vastus lateralis muscle during recovery in 8 subjects. The present findings showed that the relationship between EMG frequency decrease, lactate accumulation and fatigue, as observed in isometric protocols, cannot be simply applied to dynamic exercise.
在12名受试者进行自行车测力计运动期间，逐步增加运动强度直至最大摄氧量的100%，测量了股外侧肌和指浅屈肌的肌电图（EMG）中位功率频率。测量血乳酸浓度，以研究乳酸浓度变化与运动的股外侧肌和未运动的指浅屈肌的EMG中位功率频率变化之间的关系。结果表明，乳酸浓度并未系统性地影响中位频率：尽管血乳酸浓度显著增加，但无论是股外侧肌还是指浅屈肌，在运动期间均未发现中位频率有系统性下降。与等长运动方案中观察到的运动期间中位频率下降不同，大多数受试者出现了增加。一个有趣的发现是，8名受试者在恢复过程中股外侧肌的中位频率下降。目前的研究结果表明，等长运动方案中观察到的肌电图频率下降、乳酸积累和疲劳之间的关系不能简单地应用于动态运动。
