Movement Control
Single Leg Squat Test
Knee valgus and trunk control analysis during single leg squat.
The Single Leg Squat Test analyses lower limb alignment and trunk control during a single leg squat using front-view video. It quantifies movement quality indicators such as inward knee collapse (dynamic valgus), pelvic drop and lateral trunk lean.
What Is It Used For?
- Assessing neuromuscular control on one leg
- Monitoring movement quality in knee and hip rehabilitation
- Pre-season screening and side-to-side comparison in athletes
- Following the effect of an exercise programme on movement pattern
Measured Parameters
- Knee valgus angle (frontal plane projection angle)
- Pelvic drop (lowering of the opposite side of the pelvis)
- Lateral trunk lean angle
- Squat depth
- Left-right comparison
Setup and Camera Placement
- Place the camera directly in front of the client (frontal plane).
- The camera should be fixed at hip height, about 2.5–3 metres away.
- The whole body must be in frame from head to toe.
- The client stands barefoot, or in the same shoes each time, on a flat non-slip surface.
Tips for Accurate Measurement
- Prefer shorts so the hip, knee and ankle are clearly visible.
- The client should face the camera squarely with the foot pointing forward.
- Allow one or two practice repetitions before recording.
- Use a similar depth and speed each time; valgus can increase with depth.
- If the client loses balance, discard the repetition and try again.
How Is the Test Done?
- Select the client and the leg to be tested.
- The client stands on the test leg with the other foot off the floor and hands on hips or crossed on the chest.
- Start recording; the client squats in a controlled manner to a comfortable depth and returns.
- The movement is repeated 3–5 times.
- Repeat for the other leg and save the results.
What Will I See on the Results Screen?
- Knee valgus angle at the deepest point
- Pelvic drop and trunk lean values
- Joint points and alignment lines overlaid on the video
- A left-right comparison summary and a record stored in the profile
Interpreting the Results
- A higher valgus angle may indicate that the knee moves further towards the midline; this can relate to factors such as hip strength, ankle mobility and motor control.
- Marked pelvic drop or lateral trunk lean can be considered in terms of control around the hip.
- Side-to-side difference and change in the same leg over time are more informative than a single value.
- Two-dimensional video is a projection of three-dimensional motion; results do not predict injury risk on their own.
Clinical Use Example
In rehabilitation after anterior cruciate ligament (ACL) reconstruction, single leg control is followed with monthly serial measurements. Valgus angle and trunk lean on the operated side approaching the uninvolved side are considered, alongside other clinical criteria, when deciding on progression to the next phase.