Surface recording of the H-reflex from a relaxed flexor carpi ulnaris: Reliability and normative values for healthy young adults

Objective: H-reflex recordings of the relaxed flexor carpi ulnaris (FCU) muscle are not frequently performed in clinical or laboratory settings. There are no normative values or reliability standards. This is most likely because of technical difficulties associated with this technique. This study performed surface recordings of the H-reflex of relaxed FCU muscles to establish the normative values and the reliability of these recordings. Methods: The maximum amplitude and latency of the FCU H-reflex were recorded bilaterally in 53 healthy young adults. Normative values and interclass correlation coefficients (ICCs) were calculated. Results: The amplitude of the relaxed FCU H-reflex were recorded in nearly all participants (96 %). The FCU H-reflex average maximum amplitude was 1.35 mV. The average latency was 18.8 ms. H-reflex amplitude and latency were not statistically different among gender or limb sides. Amplitude and latency were recoded reliably both within and between sessions with ICCs ranging from 0.96 to 0.99. Conclusions: Recordings of the relaxed FCU H-reflex were readily available and could be assessed reliably within and between sessions. Significance: This method might be used more frequently in clinical and laboratory settings to examine C7 and C8 spinal segments and upper limb muscle normal function or neuromuscular pathology.