Maintaining upright posture is a complex neuromotor process involving control of multiple factors including thoracic and abdominal pressures. Control of airflow by glottal structures, a primary determinant of thoracic pressure, should therefore be important for efficient control of postural stability. This study aimed to investigate the effect of modulation of airway control on upright postural stability during postural perturbations. Standing balance was gently perturbed in the sagittal plane during 7 breathing/voicing tasks that ranged from completely closed, to partially opened or completely open glottal conditions in 11 health adult participants. Dependent measures were peak amplitude of displacement of the thorax and center of pressure (CoP). When the glottis was completely open, thoracic displacement in response to the perturbation was greater than in all other conditions, regardless of direction of perturbation. The absolute amplitude of CoP displacement was greater with backward perturbation across airway conditions and was greater at both extremes of glottal modulation. Perturbation of CoP was least during the partially opened glottal condition.These results show that airway modulation effects postural control during upright perturbations. The thorax was most stable with a static breath-holding maneuver, but optimal control of CoP displacement was during the natural dynamic mid-range airway modulation of voicing. This study suggests that glottal control may be a relevant considertation during balance training.
