Ratkevicius Aivaras, Quistorff Bjørn
NMR Center, Department of Medical Biochemistry and Genetics A, Panum Institute, University of Copenhagen, Blegdamsveg 3, DK-2200 Copenhagen N, Denmark.
Muscle Nerve. 2002 Mar;25(3):419-26. doi: 10.1002/mus.10064.
Metabolic costs of force generation were compared for constant-frequency and catchlike-inducing electrical stimulation. Repetitive catchlike-inducing trains consisted of 2 interpulse intervals (IPIs) at 12.5 ms, 1 IPI at 25 ms, and 5 IPIs at 50 ms. Constant-frequency trains consisted of 8 IPIs at 37.5 ms. One train was delivered to the peroneal nerve every 2.5 s for 36 times under ischemic conditions. Anaerobic adenosine triphosphate (ATP) turnover was determined using 31-phosphorus magnetic resonance spectroscopy (P-MRS) of the human tibialis anterior muscle. Compared with constant-frequency trains, catchlike-inducing trains produced a faster force generation and were more effective in maintaining the force--time integral as well as peak force. However, ATP costs of force generation were similar for the catchlike-inducing and constant-frequency stimulation (6.7 plus/minus 1.1 and 6.6 plus/minus 1.0 micromol ATP/kg wet weight/Ncenter dots, respectively, P = 0.601). This suggests that the positive effects of catchlike-inducing stimulation on force maintenance are mediated by potentiated Ca(2+) release from the sarcoplasmic reticulum rather than by lower metabolic costs of muscle force generation. Our findings also suggest that catchlike-inducing stimulation produces larger forces in fatigued muscle than constant-frequency trains and thus may be beneficial for muscle training or rehabilitation when muscle loading needs to be maintained in repetitive contractions.
比较了恒频和类捕捉诱导电刺激产生力量的代谢成本。重复性类捕捉诱导序列由12.5毫秒的2个脉冲间隔（IPIs）、25毫秒的1个IPI和50毫秒的5个IPIs组成。恒频序列由37.5毫秒的8个IPIs组成。在缺血条件下，每2.5秒向腓神经输送一次序列，共36次。使用人体胫骨前肌的31-磷磁共振波谱（P-MRS）测定无氧三磷酸腺苷（ATP）周转率。与恒频序列相比，类捕捉诱导序列产生力量更快，在维持力量-时间积分以及峰值力量方面更有效。然而，类捕捉诱导刺激和恒频刺激产生力量的ATP成本相似（分别为6.7±1.1和6.6±1.0微摩尔ATP/千克湿重/牛顿·秒，P = 0.601）。这表明类捕捉诱导刺激对力量维持的积极作用是由肌浆网中增强的Ca(2+)释放介导的，而不是由肌肉产生力量的较低代谢成本介导的。我们的研究结果还表明，类捕捉诱导刺激在疲劳肌肉中产生的力量比恒频序列更大，因此当需要在重复收缩中维持肌肉负荷时，可能对肌肉训练或康复有益。
