Grabiner M D, Koh T J, Miller G F
Department of Musculoskeletal Research, Cleveland Clinic Foundation, Ohio 44106.
J Orthop Res. 1991 May;9(3):391-7. doi: 10.1002/jor.1100090311.
Fatigue rates of the vastus medialis oblique and vastus lateralis muscles were compared from static and dynamic exercise. Based upon clinical observations, it was expected that the vastus medialis oblique would demonstrate greater fatigability than the vastus lateralis. However, based upon physiological and morphological considerations, it was expected that the vastus lateralis would exhibit greater fatigability than the vastus medialis oblique. In the static exercise condition, nine subjects--having no history of knee problems--maintained an isometric knee extension torque at 30 and 60% of their maximum value until exhaustion, during which time electromyography (EMG) data were collected every 10 s. The knee angle was 20 degrees flexion. In the dynamic exercise condition, a different group of seven subjects performed exercise sets consisting of eight cycles of concentric-eccentric knee extension, with a resistance equal to 40% of the maximum isometric value. The range of motion was restricted to the terminal 30 degrees of knee extension. Each set of eight repetitions was followed by a 1 s 50% maximum isometric knee extension, during which time EMG data were collected. The raw EMG data were numerically processed to extract the median frequency of the power density spectrum, which has been shown to reflect the metabolic processes associated with fatigue. Linear regression generated a slope coefficient representing the rate of change of the median frequency, with respect to contraction duration for each subject, muscle, and condition. Analyses of variance, with repeated measures from both exercise conditions suggest that "short-arc" quadriceps exercise did not selectively fatigue either the vastus medialis oblique or vastus lateralis, thereby supporting neither clinical nor physiological expected outcomes. Therefore, the clinical contention that short-arc quadriceps exercises selectively strengthen the vastus medialis oblique is questioned.
比较了股内侧斜肌和股外侧肌在静态和动态运动中的疲劳率。基于临床观察，预计股内侧斜肌比股外侧肌表现出更大的疲劳性。然而，基于生理和形态学考虑，预计股外侧肌比股内侧斜肌表现出更大的疲劳性。在静态运动条件下，九名没有膝关节问题病史的受试者将等长膝关节伸展扭矩维持在其最大值的30%和60%，直到疲劳，在此期间每10秒收集一次肌电图（EMG）数据。膝关节角度为屈曲20度。在动态运动条件下，另一组七名受试者进行了由八个同心-偏心膝关节伸展周期组成的运动组，阻力等于最大等长值的40%。运动范围限制在膝关节伸展的最后30度。每组八次重复后进行1秒的50%最大等长膝关节伸展，在此期间收集EMG数据。对原始EMG数据进行数值处理，以提取功率密度谱的中位数频率，该频率已被证明反映与疲劳相关的代谢过程。线性回归生成一个斜率系数，代表每个受试者、肌肉和条件下中位数频率相对于收缩持续时间的变化率。对两种运动条件下的重复测量进行方差分析表明，“短弧”股四头肌运动不会选择性地使股内侧斜肌或股外侧肌疲劳，因此既不支持临床预期结果，也不支持生理预期结果。因此，短弧股四头肌运动选择性增强股内侧斜肌的临床观点受到质疑。
