Arterial baroreflex modulation influences postural sway

Objective Although considered mainly a random function, postural sway is influenced by physiological factors such as respiration. A direct effect of the autonomic nervous system (ANS) on posture has never been demonstrated. To test this hypothesis, we used a pure motion-independent autonomic stimulus (neck suction) to modulate the carotid baroreceptors on a broad frequency range, distinct from that of respiration. Methods Thirteen healthy subjects (age 26 ± 5 years) were studied upright, eyes closed, and on a force platform during controlled breathing (15 breath/min, 0.25 Hz), with and without stimulation of arterial baroreceptors by sinusoidal neck suction (0 to −30 mmHg pressure) at different frequencies (0.05, 0.10, 0.125, 0.15, 0.175, 0.20, 0.30 Hz), for eight periods lasting 2 min each. The increase in sway, R–R interval and blood pressure induced at each stimulation frequency was measured by spectral analysis. Results With neck suction, we observed a significant ( p