Sex-related Differences in H-reflex Excitability and Inhibition
Abstract
The Hoffmann reflex (H-reflex), when elicited in the soleus in healthy males and females, demonstrates sex-specific differences in the neuromodulation of spinal synaptic transmission. This study investigated the sex-related differences in H-reflex excitability and inhibition. Thirty healthy young individuals, 15M (24±2yrs) and 15F (23±3yrs) participated in the study. Surface electrodes were used to elicit and record the H-reflex. Excitability was assessed by stimulating the tibial nerve, beginning at a low-intensity voltage and increasing incrementally until the maximal amplitude of the muscle response was reached. Reciprocal inhibition (RI) was assessed with a conditioning - test stimuli protocol. No significant sex-related differences in excitability were identified; however, males exhibited significantly greater RI than females. This study will add to the growing body of knowledge surrounding differences in the modulation of spinal motor control between sexes and will contribute to the significant gap in neurophysiology research involving females.