Recruitment patterns in the rat hindlimb muscle during swimming.

Cycle periods and electromyographic (EMG) burst durations of selected extensors and flexors are shorter during swimming than during running at 27 m/min, while the relative ON-OFF timing of these interrelationships are similar. The mean EMG activities of the tibialis anterior and adductor longus were higher and the soleus and medial gastrocnemius were lower during swimming than during running. Both fast and slow extensors are activated during both forms of locomotion, thus demonstrating that there is not a selective recruitment of fast or selective inhibition of slow ankle extensors during swimming as measures of muscle blood flow have suggested.