Savelberg Hans H C M, Keizer Hans A, Meijer Kenneth
Department of Human Movement Science, Faculty of Health Sciences, Universiteit Maastricht, Maastricht, The Netherlands.
J Strength Cond Res. 2007 May;21(2):589-93. doi: 10.1519/R-20766.1.
It was hypothesized that both vibration frequency and muscle length modulate the strengthening of muscles that is assumed to result from whole-body vibration (WBV). Length of knee extensor muscles during vibration is affected by the knee joint angle; the lengths of the knee extensors increase with more flexed knee joint angles. In an intervention study 28 volunteers were randomly assigned to 1 of 4 groups. Each group received 4 weeks of WBV at 1 of 3 different frequencies (20, 27, or 34 Hz) or 1 of 2 different lengths of knee extensors. Voluntary, isometric knee extension moment-angle relationship was determined. Initially, stronger subjects reacted differently to WBV than weaker participants. In stronger subjects knee extension moment did not improve; in the weaker subjects considerable improvements were observed ranging from 10 to 50%. Neither vibration frequency nor muscle length during the intervention affected the improvements. In addition to strength, the knee joint angle at which the maximal joint moment was generated (optimal joint angle) was affected. When trained at short muscle lengths, optimal angle shifted to more extend joint position. WBV training at long muscle lengths tended to induce an opposite shift. The amount of this shift tended to be influenced by vibration frequency; the lower the vibration frequency the larger the shift. Shifts of optimal lengths occurred in both weaker and stronger subjects. This study shows that muscle length during training affects the angle of knee joint at which the maximal extension moment was generated. Moreover, in weaker subjects WBV resulted in higher maximal knee joint extension moments. Vibration frequency and muscle length during vibration did not affect this joint moment gain.
据推测，振动频率和肌肉长度均会调节肌肉强化，而这种强化被认为是全身振动（WBV）所致。振动过程中膝关节伸肌的长度受膝关节角度影响；膝关节伸肌的长度会随着膝关节角度的增大而增加。在一项干预研究中，28名志愿者被随机分配到4组中的1组。每组在3种不同频率（20、27或34赫兹）中的1种频率或2种不同膝关节伸肌长度中的1种长度下接受4周的WBV训练。测定了自愿等长膝关节伸展力矩-角度关系。最初，较强壮的受试者对WBV的反应与较弱的受试者不同。在较强壮的受试者中，膝关节伸展力矩没有改善；而在较弱的受试者中，观察到有显著改善，改善幅度在10%至50%之间。干预期间的振动频率和肌肉长度均未影响这些改善情况。除了力量之外，产生最大关节力矩时的膝关节角度（最佳关节角度）也受到了影响。在短肌肉长度下进行训练时，最佳角度会向更伸展的关节位置偏移。在长肌肉长度下进行WBV训练往往会导致相反的偏移。这种偏移量往往受振动频率影响；振动频率越低，偏移量越大。较弱和较强壮的受试者均出现了最佳长度的偏移。这项研究表明，训练期间的肌肉长度会影响产生最大伸展力矩时的膝关节角度。此外，在较弱的受试者中，WBV导致了更高的最大膝关节伸展力矩。振动期间的振动频率和肌肉长度并未影响这种关节力矩的增加。
