Structure and Motion Laboratory, Royal Veterinary College, University of London, Hawkshead Lane, South Mymms AL9 7TA, UK.
J Exp Biol. 2012 Jul 15;215(Pt 14):2425-34. doi: 10.1242/jeb.066720.
The cheetah and racing greyhound are of a similar size and gross morphology and yet the cheetah is able to achieve a far higher top speed. We compared the kinematics and kinetics of galloping in the cheetah and greyhound to investigate how the cheetah can attain such remarkable maximum speeds. This also presented an opportunity to investigate some of the potential limits to maximum running speed in quadrupeds, which remain poorly understood. By combining force plate and high speed video data of galloping cheetahs and greyhounds, we show how the cheetah uses a lower stride frequency/longer stride length than the greyhound at any given speed. In some trials, the cheetahs used swing times as low as those of the greyhounds (0.2 s) so the cheetah has scope to use higher stride frequencies (up to 4.0 Hz), which may contribute to it having a higher top speed that the greyhound. Weight distribution between the animal's limbs varied with increasing speed. At high speed, the hindlimbs support the majority of the animal's body weight, with the cheetah supporting 70% of its body weight on its hindlimbs at 18 m s(-1); however, the greyhound hindlimbs support just 62% of its body weight. Supporting a greater proportion of body weight on a particular limb is likely to reduce the risk of slipping during propulsive efforts. Our results demonstrate several features of galloping and highlight differences between the cheetah and greyhound that may account for the cheetah's faster maximum speeds.
猎豹和赛狗的体型和大体形态相似，但猎豹却能达到更高的最高速度。我们比较了猎豹和赛狗的奔跑运动学和动力学，以研究猎豹如何达到如此惊人的最高速度。这也为研究四足动物的最大奔跑速度的潜在限制提供了机会，而这些限制仍知之甚少。通过结合奔跑中的猎豹和赛狗的测力板和高速视频数据，我们展示了在任何给定速度下，猎豹如何比赛狗使用更低的步频/更长的步幅。在一些试验中，猎豹的摆动时间低至与赛狗一样（0.2 秒），因此猎豹有空间使用更高的步频（高达 4.0 Hz），这可能有助于它的最高速度超过赛狗。动物四肢之间的重量分布随速度的增加而变化。在高速时，后肢支撑动物大部分的体重，猎豹在 18 米每秒时，后腿支撑其 70%的体重；然而，赛狗后腿仅支撑其 62%的体重。在特定的肢体上支撑更大比例的体重，可能会降低在推进过程中滑倒的风险。我们的研究结果展示了奔跑的几个特征，并突出了猎豹和赛狗之间的差异，这些差异可能解释了猎豹更快的最高速度。
