I've been reading a passage from Neuromechanics of Human Movement by Enoka (4th Ed. 2008). On page 270 the author talks about how voluntary movement is made possible due to "facilitation of excitatory pathway and the suppresion of inhibitory pathways [...]."

However, this does not really explain how voluntary movement starts. Elbow flexion won't happen just because the conditions are made more favorable, right? Logically there must be a starting point (e.g. descending input directly to alpha motorneurons) to elicit such movement.

I'm almost convinced that it starts with activation of gamma motorneurons to modulate type II afferent inputs, but seems like a baseless hunch.