Crenshaw A G, Gerdle B, Heiden M, Karlsson S, Fridén J
Centre for Musculoskeletal Research, National Institute for Working Life, Umeå, Sweden.
Acta Physiol Scand. 2000 Oct;170(2):119-26. doi: 10.1046/j.1365-201x.2000.00765.x.
The purpose of the study was to investigate changes in intramuscular pressure (IMP) (maximal during contraction - peak IMP, and between contraction, relaxation IMP - RxIMP) and surface electromyographic activity (EMG) parameters [mean frequency of the power spectrum (fmean), and signal amplitude, root mean square (RMS)] throughout 100 repetitive isokinetic contractions for six healthy subjects. Parameters were recorded simultaneously from the vastus lateralis muscle during maximal knee extension. Regression analyses revealed significant decreases for peak IMP and fmean, and an increase in RxIMP; RMS, however, did not change. All parameters demonstrated trends of change throughout the contractions that were non-linear. Details and inter relations for RxIMP and fmean were highlighted to express intramuscular fluid accumulation and fatigue development, respectively. Individual regression analyses for RxIMP revealed significant positive correlations for all subjects (range of r=0.62 to 0.89). At group level, mean RxIMP increased from 6.0 mmHg for the 1st contraction to 14.0 mmHg for the 100th contraction. For fmean, individual regressions were significantly negative for all subjects (r=-0.75 to -0.89). Fmean decreased from 89.2 Hz for the 1st contraction to 63.3 Hz for the 100th contraction. When the data were delineated between the fatigue (contractions 1-40) and endurance phases (41-100), the slopes of increase for RxIMP, and of decrease for fmean were significantly greater during the fatigue phase. RxIMP throughout the 100 contractions correlated negatively with fmean for each subject (r=-0.54 to -0.78); when delineated, the correlation between parameters was significantly greater for the fatigue as compared with the endurance phase. Relaxation IMP trends are mainly attributed to intramuscular water accumulations during repetitive contractions. In spite of consistent correlations between RxIMP and fmean a causal association could not be established. It may be suggested that a common factor occurring during the fatiguing process governs changes in RxIMP and fmean.
本研究的目的是调查六名健康受试者在100次重复等速收缩过程中肌肉内压力（IMP）（收缩时的最大值 - 峰值IMP，以及收缩与放松之间的IMP - RxIMP）和表面肌电图活动（EMG）参数[功率谱的平均频率（fmean）以及信号幅度、均方根（RMS）]的变化情况。在最大膝关节伸展过程中，同时从股外侧肌记录这些参数。回归分析显示，峰值IMP和fmean显著下降，而RxIMP增加；然而，RMS没有变化。所有参数在整个收缩过程中均呈现出非线性的变化趋势。突出显示了RxIMP和fmean的详细信息及相互关系，分别用以表示肌肉内液体蓄积和疲劳发展情况。对RxIMP进行的个体回归分析显示，所有受试者均存在显著的正相关（r值范围为0.62至0.89）。在组水平上，平均RxIMP从第一次收缩时的6.0 mmHg增加到第100次收缩时的14.0 mmHg。对于fmean，所有受试者的个体回归均为显著负相关（r值范围为 - 0.75至 - 0.89）。fmean从第一次收缩时的89.2 Hz下降到第100次收缩时的63.3 Hz。当将数据划分为疲劳阶段（收缩1 - 40次）和耐力阶段（41 - 100次）时，RxIMP的上升斜率和fmean的下降斜率在疲劳阶段显著更大。在100次收缩过程中，每个受试者的RxIMP与fmean均呈负相关（r值范围为 - 0.54至 - 0.78）；划分阶段后，与耐力阶段相比，疲劳阶段参数之间的相关性显著更大。放松IMP趋势主要归因于重复收缩过程中的肌肉内水分蓄积。尽管RxIMP和fmean之间存在一致的相关性，但无法建立因果关联。可能提示在疲劳过程中出现的一个共同因素支配着RxIMP和fmean的变化。
