Knees moving inward during a squat, often called “going out” or “caving in,” is known as dynamic knee valgus. This movement pattern is a common challenge regardless of experience level. When the knees collapse inward, it indicates a loss of alignment between the hip, knee, and ankle joints under load. Understanding this requires looking at both technique errors and physical limitations.
Identifying Technique Flaws
Knee valgus results from incorrect execution. Errors include a stance that is too narrow or too wide, preventing the femur from tracking correctly. Not turning the toes out slightly limits the external rotation needed for the knee to follow the foot’s line.
The squat should start by bending at the hips and knees simultaneously. If the movement begins by pushing the knees forward, the lower leg moves ahead of the mid-foot, forcing the knees inward for balance. A lack of core bracing permits pelvic tilt or rotation, translating into knee collapse.
Physical Limitations Causing Instability
Instability is often caused by weak gluteal muscles (Gluteus Medius and Minimus). These muscles stabilize the hip and promote external rotation. If they cannot counteract internal rotation, the knees are pulled inward.
Tight adductor muscles on the inner thigh can overpower the weaker gluteals, contributing to the inward pull. Adductors act as powerful hip extensors. When they dominate the movement, they pull the femurs into internal rotation and adduction, causing collapse.
Limited ankle dorsiflexion (the shin’s ability to move forward over the foot) is a frequent limitation forcing compensation. If the ankles lack the necessary range of motion for descent, the body seeks an alternative path. This involves the foot pronating and the knee tracking inward, resulting in knee valgus. Restricted dorsiflexion significantly increases the peak knee-valgus angle.
Immediate Adjustments During the Squat
Immediate cues can improve knee stability during a set. Cueing the lifter to “screw your feet into the floor” involves externally rotating the hips to create tension. This activates the hip abductors and external rotators, pre-tensioning the glutes. Maintain the outward tracking of the knees, ensuring alignment over the middle of the foot throughout the range of motion.
Maintaining a rigid, stable core is important. Bracing the abdominal and lower back muscles stabilizes the pelvis, the foundation for the legs. This core tension prevents the torso from shifting or tilting, overriding compensation patterns.
Targeted Exercises for Correction
Strengthening the Hips and Glutes
Addressing instability requires consistent, targeted exercises to improve strength and mobility. Effective exercises to strengthen the hip abductors and external rotators include:
- Clamshells and Glute Bridges, especially with a mini-band above the knees. The band forces the lifter to push the knees outward, reinforcing the proper movement pattern.
- Banded squats, which aid motor control training. The band cues the knees outward, helping the individual feel muscle activation.
- Lateral band walks, which isolate and strengthen the gluteal muscles.
Improving Ankle Dorsiflexion
Limited ankle dorsiflexion requires dedicated mobility drills. The half-kneeling ankle mobility drill involves driving the knee forward over the ankle while keeping the heel planted, systematically improving range of motion. This addresses tightness in the calf muscles (soleus and gastrocnemius) that restrict forward knee travel. Improving ankle flexibility allows the knee to track properly, reducing valgus compensation.
When Instability Signals Injury Risk
While a momentary inward movement (“valgus twitch”) can occur, persistent or painful instability signals a higher injury risk. The inward collapse places undue stress on the ligaments and cartilage. This stress increases the risk of conditions like patellofemoral pain syndrome or ACL injury over time.
Red flags that warrant immediate professional attention include:
- Sharp, localized pain in the knee joint, especially under load.
- The sensation of the knee “locking up” or catching.
- An audible clicking sound during the movement.
- Instability that persists even when performing bodyweight squats without external load.
- Swelling or a feeling of joint laxity.
If these symptoms occur, consult a physical therapist or sports medicine physician to rule out underlying structural damage.