Orderly recruitment of motoneurons in an acute rabbit model

Artificial muscle activation by electrical stimulation of motor nerves is characterized by poor force gradation and a relative fast onset of muscle fatigue. Muscle force gradation would improve and the onset of muscle fatigue would be delayed by mimicking the physiological recruitment order by primarily activating the small-diameter motoneurons. In this study selective anodal blocking has been used in an acute animal model to investigate the advantages of orderly recruitment. The results show that primarily activating the smaller motor units results in a reduced steepness of the recruitment curve. At low forces the twitch width increases, so a lower stimulation frequency is needed to obtain a fused contraction.