A close relationship exists between hand skill and the excitability of motor neurons innervating the postural soleus muscle in right-handed male subjects.

The claim that there is no consistent inhibition of the H-reflex from the dominant leg was examined and rejected. Hand preference was assessed by the Edinburgh Inventory, and hand skill by the peg moving task. It was re-established that there is an inverse relationship between hand skill and the excitability of motoneurons innervating the postural soleus muscle in right-handed subjects without familial sinistrality. There was no significant difference between the recovery curves from the right and left sides in subjects with familial sinistrality. There was a positive linear correlation between the asymmetry index for hand skill greater than zero (right-hand dominance) and the asymmetry index for the H-reflex recovery curve greater than zero (left dominance in motoneuronal excitability). It was concluded that there is indeed a spinal motor asymmetry in postural leg muscles related to handedness.