The Royal Veterinary College, North Mymms, Hatfield, Herts, UK.
Biol Lett. 2010 Dec 23;6(6):765-8. doi: 10.1098/rsbl.2010.0256. Epub 2010 May 19.
Idealized models of walking and running demonstrate that, energetically, walking should be favoured up to, and even somewhat over, those speeds and step lengths that can be achieved while keeping the stance leg under compression. Around these speeds, and especially with relatively long step lengths, computer optimization predicts a third, 'hybrid', gait: (inverted) pendular running (Srinivasan & Ruina 2006 Nature 439, 72-75 (doi:10.1038/nature04113)). This gait involves both walking-like vaulting mechanics and running-like ballistic paths. Trajectories of horizontal versus vertical centre of mass velocities-'hodographs'-over the step cycle are distinctive for each gait: anticlockwise for walk; clockwise for run; figure-of-eight for the hybrid gait. Both pheasants and guineafowl demonstrate each gait at close to the predicted speed/step length combinations, although fully aerial ballistic phases are never achieved during the hybrid or 'Grounded Inverted Pendular Running' gait.
理想化的行走和跑步模型表明，在能量方面，在保持受压支撑腿的情况下，行走应该在那些速度和步长上得到优先考虑，甚至在一定程度上超过这些速度和步长。在这些速度下，尤其是在相对较长的步长下，计算机优化预测了第三种、“混合”步态：（反向）钟摆式跑步（Srinivasan & Ruina 2006 Nature 439, 72-75 (doi:10.1038/nature04113)）。这种步态既涉及类似行走的跳跃力学，也涉及类似跑步的弹道路径。在步周期中，质心水平速度与垂直速度的轨迹——“速度图”——对于每种步态都是独特的：逆时针为行走；顺时针为跑步；“混合步态”为 8 字形。雉鸡和珍珠鸡都在接近预测的速度/步长组合的情况下展示了每种步态，尽管在“混合”或“地面反向钟摆式跑步”步态中，完全的空中弹道阶段从未实现。
