Abstract
BackgroundAlthough the soleus (Sol), medial gastrocnemius (MG), and lateral gastrocnemius (LG) muscles differ in function, composition, and innervations, it is a common practice is to investigate them as single H-reflex recording. The purpose of this study was to compare H-reflex recordings between these three sections of the triceps surae muscle group of healthy participants while lying and standing during three different ankle positions.MethodsThe Sol, MG and LG muscles' H-reflexes were recorded from ten participants during prone lying and standing with the ankle in neutral, maximum dorsiflexion, and maximum plantarflexion positions. Four traces were averaged for each combination of conditions. Three-way ANOVAs (posture X ankle position X muscle) with planned comparisons were used for statistical comparisons.ResultsAlthough the H-reflex in the three muscle sections differed in latency and amplitude, its dependency on posture and ankle position was similar. The H-reflex amplitudes and maximum H-reflex to M-response (H/M) ratios were significantly 1) lower during standing compared to lying with the ankle in neutral, 2) greater during standing with the ankle in plantarflexion compared to neutral, and 3) less with the ankle in dorsiflexion compared to neutral during lying and standing for all muscles (p ≤ .05).ConclusionVarying demands are required for muscles activated during distinctly different postures and ankle movement tasks.
Highlights
The soleus (Sol), medial gastrocnemius (MG), and lateral gastrocnemius (LG) muscles differ in function, composition, and innervations, it is a common practice is to investigate them as single H-reflex recording
The planned comparisons showed the average Sol, MG, and LG H-reflex maximum amplitudes during prone lying or standing were significantly less during the ankle dorsiflexion compared to the neutral ankle position (p = .0005 and .007 for Sol, Figure 2b, c; p = .001 and .04 for MG, Figure 2e, f; and p = .0005 and .0005 for LG, Figure 2h, i), the average Sol, MG, and LG maximum amplitudes did not significantly change for ankle plantarflexion compared to the neutral ankle position during prone lying (p = .2, .19, and .47), and the Sol, MG, and LG maximum amplitude was significantly greater during ankle plantarflexion compared to the neutral ankle position during the standing posture (p = .005, .024. and .01)
The results for the Sol, MG, and LG H-reflex H/M ratio were comparable to the H-reflex maximum amplitude results during prone lying or standing for all ankle positions (Table 1)
Summary
The soleus (Sol), medial gastrocnemius (MG), and lateral gastrocnemius (LG) muscles differ in function, composition, and innervations, it is a common practice is to investigate them as single H-reflex recording. Hoffmann reflex (H-reflex) recordings from muscles around the ankle joint are useful in examining the activation and inhibition during normal function. It is useful for examining dysfunctional pathologies. H-reflex recordings from the soleus (Sol) muscle are useful electrophysiological procedures for the evaluation of patients with S1 radiculopathy [1,2]. H-reflex recordings from the lateral gastrocnemius (LG) would provide L5 diagnosis in patients with radiculopathy, given that the LG is innervated by L5 more than S1 nerve roots and the Sol is innervated mostly by the S1 nerve root [3]. These cannot be valid measurements until normal activation patterns under varied recordings condition are established
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