Liubov E Amirova1,2, Nastassia M Navasiolava3, Marie-Pierre Bareille4, Arnaud Beck4, Elena S Tomilovskaya2, Inessa B Kozlovzkaya2, Guillemette Gauquelin-Koch5, Claude Gharib6,7, Marc-Antoine Custaud8,9. 1. Laboratoire BNMI, Faculté de Médecine, UMR CNRS 6214, INSERM 1083, 49045, Angers Cedex, France. 2. Institute for Biomedical Problems, Moscow, Russia. 3. CRC, Clinical Research Center, Angers University Hospital, Angers, France. 4. Institute for Space Medicine and Physiology (MEDES), Toulouse, France. 5. National Centre for Space Studies (CNES), Paris, France. 6. Claude Bernard University, Lyon, France. 7. CIDO, Saint Etienne, France. 8. Laboratoire BNMI, Faculté de Médecine, UMR CNRS 6214, INSERM 1083, 49045, Angers Cedex, France. macustaud@chu-angers.fr. 9. CRC, Clinical Research Center, Angers University Hospital, Angers, France. macustaud@chu-angers.fr.
Abstract
PURPOSE: Walking is a complex locomotor process that involves both spinal cord reflexes and cortical integration of peripheral nerve input. Maintaining an upright body position requires not only neuromuscular activity but also cardiovascular regulation. We postulated that plantar mechanical stimulation might modulate autonomic nervous system activity and, thereby, impact blood pressure adaptation during standing. METHODS:Twelve healthy subjects underwent three randomly ordered 45-min 70°-saddle tilt tests while the plantar surfaces of the feet were stimulated using specially engineered Korvit boots in the following modes: (1) no stimulation, (2) disrupted stimulation, and (3) walking mode. Orthostatic tolerance time was measured for each trial. During testing, we obtained an electrocardiogram and measured blood pressure, skin blood flow, and popliteal vein cross-sectional area. We estimated central hemodynamics, baroreflex sensitivity and heart rate variability. RESULTS:Orthostatic tolerance time was not found to differ significantly between test conditions (37.2 ± 10.4, 40.9 ± 7.6, and 41.8 ± 8.2 min, for no stimulation, disrupted stimulation, and walking mode, respectively). No significant differences between treatment groups were observed for stroke volume or cardiac baroreflex sensitivity, both of which decreased significantly from baseline during tilt testing in all groups. Cardiac sympathetic index and popliteal vein cross-sectional area increased at the end of the tilt period in all groups, without significant differences between treatments. CONCLUSIONS:Plantar mechanical stimulation is insufficient for immediate modulation of cardiac sympathetic and parasympathetic activity under orthostatic stress.
RCT Entities:
PURPOSE: Walking is a complex locomotor process that involves both spinal cord reflexes and cortical integration of peripheral nerve input. Maintaining an upright body position requires not only neuromuscular activity but also cardiovascular regulation. We postulated that plantar mechanical stimulation might modulate autonomic nervous system activity and, thereby, impact blood pressure adaptation during standing. METHODS: Twelve healthy subjects underwent three randomly ordered 45-min 70°-saddle tilt tests while the plantar surfaces of the feet were stimulated using specially engineered Korvit boots in the following modes: (1) no stimulation, (2) disrupted stimulation, and (3) walking mode. Orthostatic tolerance time was measured for each trial. During testing, we obtained an electrocardiogram and measured blood pressure, skin blood flow, and popliteal vein cross-sectional area. We estimated central hemodynamics, baroreflex sensitivity and heart rate variability. RESULTS: Orthostatic tolerance time was not found to differ significantly between test conditions (37.2 ± 10.4, 40.9 ± 7.6, and 41.8 ± 8.2 min, for no stimulation, disrupted stimulation, and walking mode, respectively). No significant differences between treatment groups were observed for stroke volume or cardiac baroreflex sensitivity, both of which decreased significantly from baseline during tilt testing in all groups. Cardiac sympathetic index and popliteal vein cross-sectional area increased at the end of the tilt period in all groups, without significant differences between treatments. CONCLUSIONS: Plantar mechanical stimulation is insufficient for immediate modulation of cardiac sympathetic and parasympathetic activity under orthostatic stress.