Walshe A D, Wilson G J, Ettema G J
School of Exercise Science and Sports Management, Southern Cross University, Lismore, New South Wales, Australia.
J Appl Physiol (1985). 1998 Jan;84(1):97-106. doi: 10.1152/jappl.1998.84.1.97.
To isolate any difference muscular contraction history may have on concentric work output, 40 trained male subjects performed three separate isokinetic concentric squats that involved differing contraction histories, 1) a concentric-only (CO) squat, 2) a concentric squat preceded by an isometric preload (IS), and 3) a stretch-shorten cycle (SSC) squat. Over the first 300 ms of the concentric movement, work output for both the SSC and IS conditions was significantly greater (154.8 +/- 39.8 and 147.9 +/- 34.7 J, respectively; P < 0.001) compared with the CO squat (129.7 +/- 34.4 J). In addition, work output after the SSC test over the first 300 ms was also significantly larger than that for the corresponding period after the IS protocol (P < 0.05). There was no difference in normalized, integrated electromyogram among any of the conditions. It was concluded that concentric performance enhancement derived from a preceding stretch of the muscle-tendon complex was largely due to the attainment of a higher active muscle state before the start of the concentric movement. However, it was also hypothesized that contractile element potentiation was a significant contributor to stretch-induced muscular performance under these conditions.
为了分离肌肉收缩历史可能对向心工作输出产生的任何差异，40名受过训练的男性受试者进行了三次单独的等速向心深蹲，涉及不同的收缩历史：1）仅向心（CO）深蹲；2）在向心深蹲之前进行等长预负荷（IS）；3）拉长-缩短周期（SSC）深蹲。在向心运动的前300毫秒内，与CO深蹲（129.7±34.4焦耳）相比，SSC和IS条件下的工作输出显著更高（分别为154.8±39.8和147.9±34.7焦耳；P<0.001）。此外，SSC测试后前300毫秒的工作输出也显著大于IS方案后相应时间段的工作输出（P<0.05）。在任何条件下，归一化的积分肌电图均无差异。得出的结论是，肌肉-肌腱复合体先前的拉伸所导致的向心性能增强主要是由于在向心运动开始前达到了更高的主动肌肉状态。然而，也有人假设，在这些条件下，收缩元件的增强是拉伸诱导的肌肉性能的一个重要因素。
