11/04/2021
Tänk vad en muskel kan prestera 😊
Did you know that..
Horses stretch and release their biceps in
a gallop, creating 100 times the energy output of non-elastic muscle! Like a catapult! (Wilson et al. 2003)
The following is taken from Wilson et al. 2003, I just thought it was so cool to see how evolution has created such efficient mechanisms for the ultimate prey animal!
At 50% of stance, the GRF is flexing the shoulder joint (resisted by the biceps), flexing the elbow (resisted by the triceps and digital flexor muscles) and extending the metacarpo–phalangeal joint (resisted by the digital flexors and suspensory ligament).
At 90% of stance, the GRF has moved further behind the
shoulder and is now also behind the elbow joint. The GRF is therefore further flexing the shoulder and extending the elbow, both of which stretch the biceps.
Through stance, the carpus is extended by the GRF and the tendinous link of lacertus fibrosis/extensor carpi radialis, and is flexed by the digital flexors and palmar carpal ligament. When the GRF approaches the neutral axis of the carpal joint, it no longer balances the digital flexors’ moment (this occurs at around 90% of stance).
The carpus then buckles forwards, destabilizing the limb and releasing the catapult.
The GRF and the digital flexors subsequently fold the collapsed joint and the limb is accelerated forwards by recoil of the biceps.
At 101% of stance, the biceps muscle is flexing the elbow and extending the shoulder.
The biceps released 243 J in 0.11 s in a gallop (2,200 W), which equates to a muscle with a peak power output of roughly 4,400 W. Equine muscle has a peak power output of about 90 W kg-1. A horse would therefore require 50 kg of non-elastic muscle to achieve the same power output as a 0.4-kg biceps muscle. The peak power output of brachiocephalicus (identified as the main forelimb protractor) would be only 220 W.
The catapult mechanism is therefore essential for rapid protraction of the equine limb!
Wilson, Alan & Watson, Johanna & Lichtwark, Glen. (2003). Biomechanics: A catapult action for rapid limb protraction. Nature. 421. 35-6. 10.1038/421035a