Influence of eye closing on the cardiovascular response to stand test on stable and unstable platforms.

Unlabelled: Check if the stimulation of the leg muscles and neuro-sensorial system during stand test influence the cardiovascular response to stand test pre and post a 7 d HDT (4 subjects).

Methods: After 20 min supine, the subject stood for 10 min, and closed the eyes for 1 min. Then he stayed 2 min stand up on ant-posterior or lateral unstable platform and closed the eyes for 30 sec. The cerebral and lower limb flow were assessed by Doppler (skin fixed sensors) and also the cerebral to femoral flow ratio (CFR).

Results: All 4 subjects were tolerant, CFR increased similarly pre and post HDT. Post HDT eye closing increased leg muscle activity, and femoral flow increased more than pre HDT, on ant-post unstable platform. The trace of the body foot pressure point was much longer post HDT on the ant-post platform.

Conclusion: Post HDT neuro-sensorial disadaptation may contribute to reduce the orthostatic tolerance at least in absence of visual references.