Postural Sway and Counterpressure Maneuvers for Pediatric Syncope

Movements that can aid in delaying or preventing syncope by recruiting skeletal muscle pumping (via compression of major veins by contracting muscle to eject blood through cardiovascular circuit) and increased sympathetic drive (via sustaining an isometric muscle contraction). In this trial, we will be evaluating two clinically recommended isometric maneuvers (crouching, and leg crossing with muscle tensing) and two novel dynamic maneuvers that comprise discrete movement that the investigators have identified in prior work (exaggerated anterior-posterior postural sway, rhythmic gluteal clenching).

Participants will stand quietly for 5-minutes on a force platform to allow the investigators to assess their typical response to orthostasis.