 |
 |
 |
|
|
|
In this section:
SML:
See also:
 |
We investigate elastic mechanisms in locomotion in a variety of species including humans, horses, ostriches and camels. | |
The limbs of compliant animals have evolved for the purpose of both fast and economical locomotion. In contrast human limbs contain a lot of muscle. We are interested in investigating the approach used by evolutionary distinct animals to deploy limb elasticity for economical locomotion. Economical locomotion systems commonly use elastic mechanisms to store and return energy throughout the gait cycle. The most obvious of these is the 'pogo stick' like action of the equine, ostrich and kangaroo limbs during foot contact with the ground, resulting from the stretching and shortening of the flexor tendons of the limbs.
It is believed that there may also be other energy saving mechanisms in animals such as the horse. Particularly Jo Watson is investigating the role of biceps in limb protraction and the function of the large tendinous portion of this muscle-tendon unit. We are also attempting to model these elastic mechanisms in the equine forelimb and investigating the roles of antagonists muscle tendon units in these elastic movements, such as the action of the triceps muscle group. Elasticity is also important in energy storage and control of human locomotion. This is the subject of a PhD program of Glen Lichtwark.
We have recently shown that, in the horse forelimb, the biceps muscle is used as the spring in a catapult to accelerate the limb off the ground at the end of the stance phase. Large athletic animals need to maximise duty factor (proportion of the stride that a limb is on the ground) to limit limb force especially at high speeds. It is therefore critical that limbs are protracted (recovered for the next stance phase) as quickly as possible. Biceps force and elastic energy stored peak at the very end of the stance phase and the catapult is released when the carpus buckles just prior to foot off. A very large muscle would be required to achieve a similar acceleration through direct contraction.
An animation of this process can be seen in the Structure and Motion Gallery. This requires a shockwave plugin (which will download automatically if required).
The paper and diagrams of the anatomy can be viewed from the Publications page.
Jo Watson
Alan Wilson
Glen Lichtwark
Justine Robilliard
Structure and Motion Lab These pages maintained by the SML Contact: Alan Wilson
