Willems M E, Stauber W T
Department of Physiology, West Virginia University, Morgantown 26506-9229, USA.
Aging (Milano). 2000 Dec;12(6):478-81. doi: 10.1007/BF03339880.
We examined whether the decline in isometric force and peak stretch force during repeated stretches of activated plantar flexor muscles was larger in old (24 months, N=5) compared with young (4 months, N=5) female Sprague Dawley rats. Thirty stretches were imposed on isometric contractions (stimulation time 1.9 s, rest periods 180 s) by ankle rotation from 90 degrees to 40 degrees at 50 degrees x s(-1). Even though muscle weights were similar [2094 +/- 54 (young) vs 2033 +/- 73 mg (old) (mean +/- SE)], the isometric force (IF) at 90 degrees before stretch 1 and peak stretch force (PSF) at 40 degrees for stretch 1 were lower in old rats [18.9 +/- 0.5 vs 15.5 +/- 1.4 N (p=0.024) and 25.8 +/- 1.3 vs 20.5 +/- 0.9 N (p=0.017)]. After the stretches, the IF deficit was similar [38.5 +/- 3.0% (young) vs 39.8 +/- 3.4% (old)] and did not recover after 1 hour of rest [35.1+/- 4.1% (young) vs 36.9 +/- 4.3% (old)]. The decline in PSF was/also similar [36.0 +/- 5.2% (young) vs 26.6 +/- 1.8% (old)]. Skeletal muscles of 24-month-old female Sprague Dawley rats were weaker than 4-month-old rats but had similar susceptibility to develop IF deficits after stretches of activated muscles.
我们研究了在激活的跖屈肌重复拉伸过程中，老年（24个月，N = 5）雌性Sprague Dawley大鼠与年轻（4个月，N = 5）雌性Sprague Dawley大鼠相比，等长力和峰值拉伸力的下降是否更大。通过将踝关节以50度×秒⁻¹的速度从90度旋转至40度，对等长收缩施加30次拉伸（刺激时间1.9秒，休息时间180秒）。尽管肌肉重量相似[2094±54（年轻）对2033±73毫克（老年）（平均值±标准误）]，但老年大鼠在第1次拉伸前90度时的等长力（IF）和第1次拉伸至40度时的峰值拉伸力（PSF）较低[18.9±0.5对15.5±1.4牛（p = 0.024）和25.8±1.3对20.5±0.9牛（p = 0.017）]。拉伸后，IF缺陷相似[38.5±3.0%（年轻）对39.8±3.4%（老年）]，并且在休息1小时后未恢复[35.1±4.1%（年轻）对36.9±4.3%（老年）]。PSF的下降也相似[36.0±5.2%（年轻）对26.6±1.8%（老年）]。24个月大的雌性Sprague Dawley大鼠的骨骼肌比4个月大的大鼠弱，但在激活肌肉拉伸后产生IF缺陷的易感性相似。
