M‐wave and H‐reflex recruitment curves in boys and men

Description

The aim of the present study was to check whether the M-wave and H-reflex recruitment curves differ between prepubertal boys and men. Eleven boys (9-11 yr) and eleven men (18-35 yr) were magnetically stimulated at the tibial nerve in a prone position. M-wave and H-reflex maximal amplitudes (Hmax; Mmax; Hmax/Mmax), thresholds, regression slopes (Hslp; Mslp; Hslp/Mslp) were extracted from M-wave and H-reflex recruitment curves and compared between the two age groups. Overall, no significant difference in M-wave and H-reflex recruitment curve parameters was found between the two populations. Nevertheless, the size of the M-wave associated to maximal H-reflex amplitude was lower in boys as compared to men when expressed relative to maximal M-wave amplitude (MHmax/Mmax: 0.18 ± 0.06 vs. 0.31 ± 0.13; P<0.05). This result suggests that the development of peripheral nerve was completed in 9-11-year-old boys and did not affect the M-wave and H-reflex recruitment curves parameters. In neuromuscular function studies, it implies that Hmax/Mmax and Hslp/Mslp could be used indifferently to compare spinal motoneuron excitability between 9-11-year-old boys and men. Conversely, evoking H-reflexes at a given percentage of Mmax may bias the comparison between boys and men.

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