IMU-based Outcome Assessment

The IMU battery consists of five standardised sub-assessments administered in a fixed sequence from least to most physically demanding, with a total duration of approximately 30 minutes. Outcome assessors conducting all IMU-based assessments are blinded to group allocation, with separate administrative systems preventing calendar access. The trial uses a validated wearable system of five wireless IMUs integrated with a pressure platform, communicating via Bluetooth Low Energy at 60 Hz with angular resolution of 0.1°. Scapular retraction with a standardised resistance band was selected as an upper extremity IMU assessment because it replicates the pulling and hauling movements central to adapted sailing. Postural control (COP path length and sway area) and upper extremity kinematics (movement smoothness) are designated the highest-priority IMU parameters, reflecting the two primary physical demands of sailing.