Related Experiment Video
Updated: Jul 17, 2026
Non-invasive Assessment of Changes in Corticomotoneuronal Transmission in Humans
Published on: May 24, 2017
Characterizing Soleus Muscle Response to Targeted Plantar Nerve Modulation Using Mechanomyography
1Sonostics, Inc, Endicott, NY, USA.
Objective:
The human soleus muscles are essential for maintaining cardiac output during upright posture, but age and disuse lead to soleus atrophy, causing numerous health complications in older adults. Here, we investigate the influence of plantar nerve stimulation on soleus muscle activity focusing on ways exogenous stimulation technology can be optimized for the rejuvenation of the soleus muscles.
Materials And Methods:
Mechanomyographic (MMG) spectra were obtained to characterize soleus dynamics in adults during quiet sitting. Spectra from older women in the presence, and absence, of plantar nerve modulation, were compared with reference spectra obtained from young men and women.
Results:
The young male soleus shows remarkably high levels of tonic muscle activity during quiet sitting, with frequency peaks indicative of intensive type I and type IIa fiber involvement. Young women show lower frequency type I activity and greatly reduced type IIa activity. Spectra from older women reflect significant reductions in type I activity, consistent with disuse atrophy. The immediate response of the soleus muscle to plantar nerve modulation during quiet sitting is a significant enhancement of activity across the type I fiber spectrum (p < 0.0001), whereas sustained daily use of plantar nerve modulation by older women is associated with an enhancement in fiber dynamics characteristic of that observed in young women.
Conclusions:
MMG analysis provides a sensitive and quantitatively reproducible assessment that has confirmed the ability of plantar nerve modulation to enhance soleus muscle performance in both the short and long term. Because soleus atrophy in older adults leads to numerous detrimental health conditions in these adults, the ability to rejuvenate the soleus muscles through simple, noninvasive, nerve modulation therapy supports use of this strategy as an effective clinical intervention. Results obtained here also indicate that MMG can play an important role in optimizing nerve modulation strategies in this application area.
Related Concept Videos
01:20Motor Unit Stimulation
The latent period of contraction marks the onset of excitation-contraction coupling, when the action potential propagates across the sarcolemma, preparing the muscle fibers for contraction. As the fibers enter the contraction phase, the...
01:22Muscle Stimulation Frequency
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
01:22Somatic Spinal Reflexes
One of the most well-known somatic spinal reflexes is the stretch reflex, which is activated by the sudden stretching of a muscle. This reflex involves the activation of specialized sensory receptors called muscle spindles, which are located in the muscle tissue and detect changes in the length and speed of muscle contractions. When a muscle is suddenly...
01:14Design Example: Frog Muscle Response
When the switch connecting the RL circuit is closed, a brief muscle contraction is observed. This is because, at a steady state, the inductor acts like a short circuit,...