School of Physiotherapy and Exercise Science, Griffith University, Gold Coast Campus, QLD 4222, Australia.
J Exp Biol. 2010 Mar 1;213(5):707-14. doi: 10.1242/jeb.038026.
Muscle power output and efficiency during cyclical contractions are influenced by the timing and duration of stimulation of the muscle and the interaction of the muscle with its mechanical environment. It has been suggested that tendon compliance may reduce the energy required for power production from the muscle by reducing the required shortening of the muscle fibres. Theoretically this may allow the muscle to maintain both high power output and efficiency during cyclical contraction; however, this has yet to be demonstrated experimentally. To investigate how tendon compliance might act to increase muscle power output and/or efficiency, we attached artificial tendons of varying compliance to muscle fibre bundles in vitro and measured power output and mechanical efficiency during stretch-shorten cycles (2 Hz) with a range of stretch amplitudes and stimulation patterns. The results showed that peak power, average power output and efficiency (none of which can have direct contributions from the compliant tendon) all increased with increasing tendon compliance, presumably due to the tendon acting to minimise muscle energy use by allowing the muscle fibres to shorten at optimal speeds. Matching highly compliant tendons with a sufficiently large amplitude length change and appropriate stimulation pattern significantly increased the net muscle efficiency compared with stiff tendons acting at the same frequency. The maximum efficiency for compliant tendons was also similar to the highest value measured under constant velocity and force conditions, which suggests that tendon compliance can maximise muscle efficiency in the conditions tested here. These results provide experimental evidence that during constrained cyclical contractions, muscle power and efficiency can be enhanced with compliant tendons.
肌肉的功率输出和效率在周期性收缩过程中受到肌肉刺激的时间和持续时间以及肌肉与机械环境相互作用的影响。有人认为，肌腱顺应性可以通过减少肌肉纤维所需的缩短来降低肌肉产生功率所需的能量。从理论上讲，这可能使肌肉在周期性收缩过程中既能保持高功率输出又能保持高效率；然而，这尚未在实验中得到证明。为了研究肌腱顺应性如何增加肌肉的功率输出和/或效率，我们在体外将具有不同顺应性的人工肌腱附着在肌纤维束上，并在 2 Hz 的拉伸-缩短循环（2 Hz）中测量了一系列拉伸幅度和刺激模式下的功率输出和机械效率。结果表明，峰值功率、平均功率输出和效率（这些都不能直接受到顺应性肌腱的贡献）都随着肌腱顺应性的增加而增加，这可能是由于肌腱通过允许肌肉纤维以最佳速度缩短来最小化肌肉能量的使用。将高顺应性肌腱与足够大的振幅长度变化和适当的刺激模式相匹配，与在相同频率下作用的刚性肌腱相比，显著提高了净肌肉效率。顺应性肌腱的最大效率也与在恒定速度和力条件下测量到的最高值相似，这表明在测试的条件下，肌腱顺应性可以最大限度地提高肌肉效率。这些结果提供了实验证据，即在受限制的周期性收缩过程中，使用顺应性肌腱可以增强肌肉的功率和效率。
