HOPPING FREQUENCY IN HUMANS - A TEST OF HOW SPRINGS SET STRIDE FREQUENCY IN BOUNCING GAITS
HOPPING FREQUENCY IN HUMANS - A TEST OF HOW SPRINGS SET STRIDE FREQUENCY IN BOUNCING GAITS
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DOI：
10.1152/jappl.1991.71.6.2127
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发表时间：
1991-12-01
影响因子：
3.3
通讯作者：
TAYLOR, CR
中科院分区：
文献类型：
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作者：
FARLEY, CT;BLICKHAN, R;TAYLOR, CR
肌腱弹簧中弹性能量的储存和恢复在跑步、跳跃、小跑和疾驰中很重要。 我们假设，动物选择的步频，他们的行为最像简单的弹簧质量系统。 如果使用更高或更低的频率，它们将不像简单的弹簧质量系统那样工作，弹性能量的存储和恢复将减少。 我们通过让人类在跑步机上以一定的速度向前跳跃，并以一定的频率跳跃到位来测试这一假设。 该机构被建模为一个简单的弹簧-质量系统，并通过使用测力平台测量的弹簧的属性。 我们的受试者在跑步机上向前跳跃和原地跳跃时使用的频率几乎相同（“首选频率”，2.2跳/秒）。 在这个频率下，物体的行为就像一个简单的弹簧-质量系统。 与我们的预测相反，当受试者以更高的频率跳跃时，它也表现得像一个简单的弹簧质量系统，达到他们所能达到的最大值。 然而，在更高的频率下，可用于向地面施加力的时间（地面接触时间）更短，可能导致产生肌肉力量的成本更高。 在低于优选频率的频率下，正如该假设所预测的那样，身体没有以弹簧的方式表现，并且似乎弹性能量的储存和恢复减少了。 类似弹簧的行为和在优选频率下的长的地面接触时间的组合应该使产生肌肉力量的成本最小化。
The storage and recovery of elastic energy in muscle-tendon springs is important in running, hopping, trotting, and galloping. We hypothesized that animals select the stride frequency at which they behave most like simple spring-mass systems. If higher or lower frequencies are used, they will not behave like simple spring-mass systems, and the storage and recovery of elastic energy will be reduced. We tested the hypothesis by having humans hop forward on a treadmill over a range of speeds and hop in place over a range of frequencies. The body was modeled as a simple spring-mass system, and the properties of the spring were measured by use of a force platform. Our subjects used nearly the same frequency (the "preferred frequency," 2.2 hops/s) when they hopped forward on a treadmill and when they hopped in place. At this frequency, the body behaved like a simple spring-mass system. Contrary to our predictions, it also behaved like a simple spring-mass system when the subjects hopped at higher frequencies, up to the maximum they could achieve. However, at the higher frequencies, the time available to apply force to the ground (the ground contact time) was shorter, perhaps resulting in a higher cost of generating muscular force. At frequencies below the preferred frequency, as predicted by the hypothesis, the body did not behave in a springlike manner, and it appeared likely that the storage and recovery of elastic energy was reduced. The combination of springlike behavior and a long ground contact time at the preferred frequency should minimize the cost of generating muscular force.