Inhibitory influence of soleus massage onto the medial gastrocnemius H-reflex

It has previously been reported that the soleus Hoffmann (H-)reflex is diminished in amplitude during a massage of the ipsilateral triceps surae. A question arises as to the origin of this decrease. The purpose of this study was to determine whether massage does indeed diminish motoneuronal excitability or whether the decrease is an artefact associated with the experimental procedures, i.e. saturation of the transmission capacity of the afferent pathway. H-reflexes and the corresponding muscle (m-)responses were recorded from the medial gastrocnemius (MG) muscle during a 3-minute massage of the ipsilateral soleus muscle in 12 neurologically healthy adults during 4 control conditions (C1, C2, C4, C5) and 1 experimental (C3-massage) condition. Peak-to-peak mean amplitudes of the MG H-reflex obtained during massage were significantly reduced in comparison to all control values recorded while the subjects were at rest. These results suggest that massage does indeed diminish motoneuronal excitability, since these effects were not restricted to the homonymous motoneurone pool, but could also be demonstrated for a close synergistic muscle, uninvolved in the massage.