Effects of plantar stimulation on cardiovascular response to orthostatism.
OBJECTIVE
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.
Laboratoire BNMI, Faculté de Médecine, UMR CNRS 6214, INSERM 1083, 49045, Angers Cedex, France.|Institute for Biomedical Problems, Moscow, Russia.
Liubov E
LE
Amirova
CRC, Clinical Research Center, Angers University Hospital, Angers, France.
Nastassia M
NM
Navasiolava
Institute for Space Medicine and Physiology (MEDES), Toulouse, France.
Marie-Pierre
MP
Bareille
Institute for Space Medicine and Physiology (MEDES), Toulouse, France.
Arnaud
A
Beck
Institute for Biomedical Problems, Moscow, Russia.
Elena S
ES
Tomilovskaya
Institute for Biomedical Problems, Moscow, Russia.
Inessa B
IB
Kozlovzkaya
National Centre for Space Studies (CNES), Paris, France.
Guillemette
G
Gauquelin-Koch
Claude Bernard University, Lyon, France.|CIDO, Saint Etienne, France.
Claude
C
Gharib
Laboratoire BNMI, Faculté de Médecine, UMR CNRS 6214, INSERM 1083, 49045, Angers Cedex, France. macustaud@chu-angers.fr.|CRC, Clinical Research Center, Angers University Hospital, Angers, France. macustaud@chu-angers.fr.
Marc-Antoine
http://orcid.org/0000-0002-3721-9407
MA
Custaud
D000222:Adaptation, Physiological / Q000502:physiology; D000328:Adult; D001794:Blood Pressure / Q000502:physiology*; D002302:Cardiac Output / Q000502:physiology*; D005528:Foot / Q000502:physiology; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology; D010275:Parasympathetic Nervous System / Q000502:physiology; D010812:Physical Stimulation / Q000379:methods*; D004856:Postural Balance / Q000502:physiology*; D011187:Posture / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology; D014110:Touch / Q000502:physiology; D016138:Walking / Q000502:physiology*
Autonomic nervous system; Korvit; Proprioception; Tilt test; Weightlessness
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