Fall prevention is a growing concern as our elderly population reflects a greater proportion of our population. Some muscles have been shown to exhibit a decrease in response as they become accustomed to certain types of stimulation and perturbations, dependant on the task and the muscle observed. This is possible by analyzing the relationship between muscle activity and stimulation in human participants. 

We measured the response to galvanic vestibular stimulation in the medial gastrocnemius and soleus muscles. Galvanic vestibular stimulation is when electric current is sent through pads placed over the mastoid processes on each side, which are found behind the ears. This induces a nerve impulse to be generated and sent from the vestibular nerve to the appropriate processing centers in the brain. This results in the brain thinking the body is losing its balance, since they head is being stimulated to change its orientation, causing a sway in the posture.

15 healthy participants were recruited from the local university, and screened for any neurological disease. The goal was to determine if the medial gastrocnemius and soleus muscles also experience a decrease in response, over one hour of walking with the stimulation on a treadmill. Through the analysis of the relationship between muscle activity and stimulation, we did not find any significant decrease in muscle activity over time. The results cannot however be widespread to other muscles or other tasks, and so more research is needed to better understand how muscle response to dynamic tasks is organized.