MECHANICS OF HOPPING BY KANGAROOS (MACROPODIDAE)
MECHANICS OF HOPPING BY KANGAROOS (MACROPODIDAE)
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DOI：
10.1111/j.1469-7998.1975.tb05983.x
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发表时间：
1975-01-01
影响因子：
2
通讯作者：
VERNON, A
中科院分区：
文献类型：
--
作者：
ALEXANDER, RM;VERNON, A
对袋鼠和小袋鼠跳跃的力台记录和电影进行了分析，以获得有关跳跃的能量学以及作用于肌肉、肌腱和胫骨的应力的数据。分析所需的定量解剖数据已从X射线照片和解剖中获得。结果表明，势能和外动能的涨落占跳跃能量消耗的大部分，内动能的涨落相对不重要。有证据表明，大量的能量储蓄的影响，在腓肠肌和跖肌腱的能量的弹性存储。弹性机制在高速下特别有效，并且似乎解释了Dawson和Taylor（1973）的观察，即氧消耗在整个跳跃速度范围内或多或少是恒定的。提出了一种跳频的数学模型。本文对袋鼠和沙袋鼠跳跃时的受力情况进行了研究，并对它们的跳跃过程进行了力台记录和影片拍摄，结果表明，袋鼠和沙袋鼠在地面上所受的最大力约为体重的6倍。在脚着地的整个过程中，作用在地面上的力改变方向，因此它总是或多或少地与质心在一条直线上。因此，在接触阶段，动物稍微减速，然后再次加速，在每一跳中发生的势能波动在高速时比低速时略小。外部动能的波动随着速度的增加而增加，并占高速跳跃的大部分能量成本。内部动能的波动（由于肢体的加速和减速）相对较小。当双脚着地时，髋关节伸肌作正功，膝关节伸肌作负功，踝关节伸肌作负功，然后作正功。通过跟腱中能量的弹性储存，跳跃的能量消耗大大减少。在袋鼠以中等速度跳跃的情况下，计算出的节省是40%。在腿部肌肉，肌腱和胫骨中开发的最大应力已被计算和讨论的肌肉，肌腱和骨骼的已知属性。当动物跳跃时，躯干会倾斜，因为两条腿同时向前和向后摆动。适当的尾部运动会减少，但不会消除，这种影响。本文提出了跳跃的数学理论，并用来研究不同跳跃技术的优点。Dawson和Taylor（1973）发现，随着跳跃速度的增加，袋鼠的耗氧率略有下降，这可能是由于在高速下弹性储能的作用增加。
Force‐platform records and films of kangaroos and a wallaby hopping have been analysed to obtain data about the energetics of hopping and about the stresses which act in muscles, tendons and the tibia. The quantitative anatomical data required for the analysis have been obtained from X‐radiographs and dissections. It is shown that fluctuations of potential energy and external kinetic energy account for most of the energy cost of hopping; fluctuations of internal kinetic energy are relatively unimportant. Evidence is presented that large savings of energy are effected by elastic storage of energy in the gastrocnemius and plantaris tendons. The elastic mechanism is particularly effective at high speeds and seems to account for the observation of Dawson & Taylor (1973) that oxygen consumption is more or less constant over the whole range of hopping speeds. A mathematical model of hopping is presented. The stresses which occur in hopping are discussed.SummaryForce platform records and films have been made of kangaroos and a wallaby hopping.The maximum forces exerted on the ground were about six times body weight. The force exerted on the ground changes direction, throughout the period when the feet are on the ground, so that it is always more or less in line with the centre of mass. Consequently the animal decelerates a little and then accelerates again, during the contact phase.The fluctuations of potential energy which occur in each hop are slightly smaller at high speeds than at low ones. Fluctuations of external kinetic energy increase with speed and account for most of the energy cost of hopping at high speeds. Fluctuations of internal kinetic energy (due to acceleration and deceleration of the limbs) are relatively small. While the feet are on the ground the extensor muscles of the hip do positive work, those of the knee negative work and those of the ankle negative work followed by positive work. The energy cost of hopping is reduced substantially by elastic storage of energy in the Achilles tendon. In the case of a wallaby hopping at moderate speed the calculated saving was 40%. The maximum stresses developed in leg muscles, tendons and the tibia have been calculated and are discussed in relation to the known properties of muscle, tendon and bone. The trunk pitches as the animal hops because the two legs swing forwards and back simultaneously. Appropriate tail movements reduce, but do not eliminate, this effect. A mathematical theory of hopping is presented and used to investigate the merits of different hopping techniques.Dawson & Taylor's (1973) discovery that the rate of oxygen consumption of kangaroos decreases a little, as hopping speed increases, is probably to be explained by the increased role of elastic storage of energy at high speeds.