Hodgson J A, Wichayanuparp S, Recktenwald M R, Roy R R, McCall G, Day M K, Washburn D, Fanton J W, Kozlovskaya I, Edgerton V R
Department of Physiological Science, University of California, 621 Charles E. Young Dr. South, Los Angeles, CA 90095, USA.
J Neurophysiol. 2001 Sep;86(3):1430-44. doi: 10.1152/jn.2001.86.3.1430.
Continuous intramuscular electromyograms (EMGs) were recorded from the soleus (Sol), medial gastrocnemius (MG), tibialis anterior (TA), and vastus lateralis (VL) muscles of Rhesus during normal cage activity throughout 24-h periods and also during treadmill locomotion. Daily levels of MG tendon force and EMG activity were obtained from five monkeys with partial datasets from three other animals. Activity levels correlated with the light-dark cycle with peak activities in most muscles occurring between 08:00 and 10:00. The lowest levels of activity generally occurred between 22:00 and 02:00. Daily EMG integrals ranged from 19 mV/s in one TA muscle to 3339 mV/s in one Sol muscle: average values were 1245 (Sol), 90 (MG), 65 (TA), and 209 (VL) mV/s. The average Sol EMG amplitude per 24-h period was 14 microV, compared with 246 microV for a short burst of locomotion. Mean EMG amplitudes for the Sol, MG, TA, and VL during active periods were 102, 18, 20, and 33 microV, respectively. EMG amplitudes that approximated recruitment of all fibers within a muscle occurred for 5-40 s/day in all muscles. The duration of daily activation was greatest in the Sol [151 +/- 45 (SE) min] and shortest in the TA (61 +/- 19 min). The results show that even a "postural" muscle such as the Sol was active for only approximately 9% of the day, whereas less active muscles were active for approximately 4% of the day. MG tendon forces were generally very low, consistent with the MG EMG data but occasionally reached levels close to estimates of the maximum force generating potential of the muscle. The Sol and TA activities were mutually exclusive, except at very low levels, suggesting very little coactivation of these antagonistic muscles. In contrast, the MG activity usually accompanied Sol activity suggesting that the MG was rarely used in the absence of Sol activation. The results clearly demonstrate a wide range of activation levels among muscles of the same animal as well as among different animals during normal cage activity.
在24小时的正常笼内活动期间以及跑步机运动期间，连续记录恒河猴比目鱼肌（Sol）、内侧腓肠肌（MG）、胫骨前肌（TA）和股外侧肌（VL）的肌电图（EMG）。从五只猴子获得了MG肌腱力和EMG活动的每日水平，并从另外三只动物获得了部分数据集。活动水平与明暗周期相关，大多数肌肉的峰值活动出现在08:00至10:00之间。活动水平最低的时段通常在22:00至02:00之间。每日EMG积分范围从一块TA肌肉中的19mV/s到一块Sol肌肉中的3339mV/s：平均值分别为1245（Sol）、90（MG）、65（TA）和209（VL）mV/s。每24小时期间Sol的平均EMG幅度为14微伏，而短时间运动时为246微伏。活动期间Sol、MG、TA和VL的平均EMG幅度分别为102、18、20和33微伏。所有肌肉中，近似募集肌肉内所有纤维的EMG幅度每天出现5至40秒。每日激活持续时间在Sol中最长[151±45（SE）分钟]，在TA中最短（61±19分钟）。结果表明，即使是像Sol这样的“姿势”肌肉，一天中也仅活跃约9%的时间，而活跃度较低的肌肉一天中活跃约4%的时间。MG肌腱力通常非常低，与MG的EMG数据一致，但偶尔会达到接近该肌肉最大发力潜力估计值的水平。Sol和TA的活动相互排斥，除了在非常低的水平，这表明这些拮抗肌很少共同激活。相比之下，MG的活动通常伴随着Sol的活动，这表明在没有Sol激活的情况下，MG很少被使用。结果清楚地表明，在正常笼内活动期间，同一动物的不同肌肉以及不同动物的肌肉之间存在广泛的激活水平差异。
