The Influence of Hypoxic Hypoxia and Antiorthostatic Hypokinesia on the Activity of Motoneuron Pools in Man

Abstract

The paper presents study results of the possible modulating effects of intermittent normobaric hypoxic hypoxia and antiorthostatic hypokinesia on motoneuron pools activity m. soleus and m. gastrocnemius. The unidirectional conditioning of the monosynaptic spinal H-reflex was revealed under non-specific effects of hypoxia and antiorthostasis. After 19 days of exposure, an increase in the amplitudes of the H- and M- responses, activation thresholds of the action potential of Ia sensory fibers was observed, which led to the induction of a maximal H-response in both muscles at a greater stimulus level. There was also a pronounced decrease in the H-reflex depression, which is apparently associated with a weakening effect of suprasegmental control systems in the cumulative effect of a 19-day intermittent (interval) normobaric hypoxic hypoxia and antiorthostatic hypokinesia.