Mechanomyographic responses during recruitment curves in the soleus muscle

Introduction: In this study we examined relationships among mechanomyographic (MMG), electromyographic (EMG), and peak twitch torque (PTT) responses as well as test–retest reliability when recorded during recruitment curves in the soleus muscle. Methods: PTT, EMG (M-wave, H-reflex), and MMG responses were recorded during recruitment curves in 16 subjects (age 24 ± 2 years) on 2 separate days. The sum of the M-wave and H-reflex (M+H) was calculated. Correlations among variables and test–retest reliability were determined. Results: MMG was correlated with PTT (mean r = 0.93, range r = 0.59–0.99), the M-wave (0.95, 0.04–0.98), and M+H (0.91, 0.42–0.97), but was unrelated to the H-reflex (–0.06, –0.56 to 0.47). Reliability was consistently high among most variables, but normalizing to the maximum value improved MMG reliability and the minimum detectable change. Conclusion: MMG responses predicted 86%–90% of the variability in PTT, M-wave, and M+H; thus, MMG may be a useful alternative for estimating twitch torque and maximal activation. Muscle Nerve 56: 107–116, 2017.