Fatigue diminishes motoneuronal excitability during cycling exercise

Fatigue during whole body exercise influences the efficacy of the corticospinal pathway. Specifically, the augmented motoneuronal excitability typically observed with a given increase in muscle activation during cycling in the absence of fatigue is abolished during the same exercise performed in the presence of fatigue. This suggests that the previously observed unaltered corticospinal excitability from start of intense leg cycling to exhaustion is partly determined by motoneuronal inhibition/disfacilitation obscuring the facilitatory effects resulting from muscle activation.