Multielectrode recordings of tibial nerve H-reflexes at various triceps surae muscle sites in the right and left legs.

The purpose of the study was to determine the laterality of tibial nerve H-reflexes recorded at various triceps surae muscle sites. In 10 college-aged adults, maximum H-reflexes and maximum M-waves were measured in the right and left legs from the following bipolar surface elctromyographic (EMG) recording sites: (1) the belly of medial gastrocnemius muscle; (2) the belly of the lateral gastrocnemius muscle; (3) proximal soleus muscle location, 1 cm below the inferior margin of the two heads of gastrocnemius; (4) mid soleus muscle location, 3 cm below the proximal site; and (5) distal soleus muscle location, 3 cm below the mid site. Peak-to-peak EMG values of the evoked muscle responses were analyzed using leg by muscle site repeated measures ANOVA models and linear regression models to determine the laterality of the tibial nerve H-reflex. This multielectrode recording technique indicated that spinal responses evoked in the triceps surae muscle are symmetrical in humans.