ABSTRACT
In Recent years, recording of the H-reflex recruitment curve for assessment of the excitability of group I[a] afferent monosynaptic reflex has been growing. The purpose of this study was to evaluate the reliability of H-reflex recruitment curve parameters of gasterosoleus muscle in the assessment of motor neuron pool excitability. In this descriptive study, 50 non-athlete healthy volunteers were assessed. Percutaneously, 40 electrical pulses of 1 millisecond duration and 3 stimulations per each stimulus intensity were induced on tibial nerves and H-reflex recruitment curve were recorded in 4 phases. Also, each person was assessed in two sessions with 1-week interval. The intraclass correlation coefficients [ICCs] was obtained between 0.97-0.99 for inter-session reliability of intensity for recording the threshold, H[Max] and H[Last] reflexes, amplitude of H[Max], and the total slope of the ascending and descending arms. The inter-session correlation coefficient [test-retest] of these variables were obtained between 0.91-0.95 for soleus muscle, and the inter-session ICCs for peak-to-peak amplitude of H[Max] and the total slope of the ascending arm of gastrocnemius were obtained 0.65 and 0.67. The slope of initial and final three points of the ascending arm revealed a different reliability in inter-session and intra-session reliability analysis [0.64-0.96]. The reliability analysis showed a high inter-session and intra-session ICCs for the functional principal components of soleus recruitment curve. Also, recruitment curve parameters, such as intensity for record of threshold and H[Max] of soleus and lateral gastrocnemius muscles as well as total slope of ascending and descending arms, and peak to peak amplitude of H[Max] of soleus muscle had a very high Reliability