A model to investigate contribution of recruitment and rate coding in human muscle

The estimation method for the relative contribution of recruitment and rate coding is devised based on a force generation model. The necessary data for estimation are the number of MUs, their size, firing rate and the characteristics between motoneuron firing rate and force. We measured all data and applied this method to the brachialis muscle and the extensor digitorum comminus muscle. Our results showed that the relative contribution of the recruitment was 35.6% in the extensor digitorum comminus muscle at 60% of MVC, though it was 59.5% in the brachialis muscle. Almost over the whole range of muscle force, the relative contribution of the recruitment in the extensor digitorum comminus muscle was smaller than that in the brachialis muscle