Effects of mechanical stimulation of sole support zones on the H-reflex characteristics under conditions of support unloading

The effects of mechanical stimulation of the sole support zones on the state of the m. soleus moto-neuron pool in humans have been studied under 7-day support unloading conditions, which were simulated using a dry immersion (DI) model. The excitability of the m. soleus motoneuron pool was estimated by the H-reflex amplitude normalized by the maximal M-wave amplitude before, during, and after immersion exposure. The results were compared for two groups of volunteers, i.e. a control group, which was subjected only to immersion exposure, and a test group, in which mechanical stimulation in locomotion regimens was applied daily during DI. The relative H-reflex amplitude increased during immersion in the control group, whereas such alterations were not detected in the test group.