Overview
The Y Balance Lower Quarter Test is a standardized, reliable, and widely used clinical assessment tool designed to evaluate an individual’s dynamic single-leg balance and neuromuscular control at their “limits of stability.” It is often employed to identify injury risk, track rehabilitation progress, and determine readiness for return to sport.Instructions
Stand barefoot on one leg (the stance leg) in the center of a specialized platform or marked “Y” shape on the floor. While maintaining balance on the stance leg, use the mobile leg to reach as far as possible in three specific directions:- Anterior (forward): Reaching directly forward from the stance foot.
- Posteromedial (backward and inward): Reaching diagonally backward and across the body.
- Posterolateral (backward and outward): Reaching diagonally backward and away from the body.
Example Videos
Left
Right
Dimensions
Required inputs for processing:- Footedness: The foot maintaining balance [‘left’, ‘right’]
- Direction: The direction of the reach [‘Anterior’, ‘Posteromedial’, ‘Posterolateral’]
Generic Outputs
Every capture includes session metadata, standard joint angle/velocity time series, and 3D keypoint positions common to all movements. See Generic Outputs for the full list.Events
Discrete Metrics
Notes
- Kinematic data typically captured at 30-60 Hz for stability activities
- Test requires footedness specification (‘left’ or ‘right’)
- Leg length is used to normalize reach distance. Relative reach distance of 1.1 = reaching 110% of average leg length.
- Knee medial translation is a valgus displacement measure: how far did the knee move laterally?