Task difficulty and modification of spinal motor neuron activity in motor learning

Abstract

[Purpose] The purpose of this study was to examine the progression of motor learning and the soleus H-reflex changes induced by repetitive training of two tasks with different difficulty levels. [Participants and Methods] Twenty-one healthy adults were assigned to two groups: high and low difficulty training groups. They performed a motor task on a wobble board according to their group level of difficulty. The task error, the soleus H-reflex, and electromyography were measured at baseline and at the end of the training. [Results] The amplitude of the soleus H-reflex and the tibialis anterior muscle activity declined after training in the high difficulty training group. The task error declined significantly more in the low difficulty training group. [Conclusion] The results of the present study suggest that task difficulty modulates the progression of motor learning which is accompanied by a change in spinal motor neuron activity induced by training.