The overhead squat (OHS) is often used as a dynamic assessment tool to evaluate the body’s ability to maintain stability and mobility under load. This assessment quickly reveals movement compensations that indicate muscle imbalances, which might increase the risk of injury. One of the most common faults observed is knee valgus, where the knees collapse inward toward the midline of the body during the downward phase of the squat. Analyzing this movement identifies the underlying muscular causes, involving a combination of overactive, tight muscles and underactive, weak stabilizers.
Understanding Knee Valgus in the Overhead Squat
Knee valgus is a complex movement pattern characterized by a three-part action at the hip, knee, and ankle joints. The fault begins at the hip, where the femur rotates internally and adducts (moves toward the center of the body). The knee follows this inward movement, shifting stress away from the center of the joint and onto the medial structures. This deviation is often compounded by the foot over-pronating, or flattening, to compensate for the lack of stability further up the kinetic chain.
This inward collapse places excessive strain on the ligaments, tendons, and cartilage of the knee, particularly the anterior cruciate ligament (ACL). Repeated or high-load movements with knee valgus can significantly increase the risk of a non-contact ACL tear. Furthermore, this compensation pattern represents inefficiency, as misdirected forces prevent the gluteal muscles from maximizing their strength to power the squat. Addressing this movement dysfunction is crucial for both injury prevention and performance enhancement.
Identifying the Primary Overactive Muscle Groups
Overactive muscles are excessively tight and actively pull the hip and knee into the valgus position. The adductor complex, located on the inner thigh, is a primary culprit, including the adductor magnus, longus, and brevis. When overactive, the adductors pull the femur toward the midline, directly contributing to the inward collapse of the knee. This tension is often exacerbated by prolonged sitting, which keeps the adductors in a shortened position.
Another significant group is the Tensor Fasciae Latae (TFL), a small muscle on the outside of the hip that connects to the tough iliotibial band (IT Band). The TFL is a hip flexor and internal rotator; when tight, it increases the inward rotation of the femur, pulling the knee into valgus. The short head of the biceps femoris, one of the hamstring muscles, is also implicated. This muscle contributes to the internal rotation of the lower leg, which further destabilizes the knee joint during the squat motion.
The Role of Underactive Stabilizers
Movement faults like knee valgus are caused by an imbalance where stabilizing muscles are too weak to counteract the pull of tight muscles. The most consistently identified underactive muscles are the Gluteus Medius and Gluteus Maximus. The Gluteus Medius is responsible for hip abduction and resists the inward collapse of the knee by externally rotating the femur. When weak, it allows the hip to adduct and internally rotate, initiating the valgus movement.
The Gluteus Maximus, the largest muscle of the hip, is a powerful external rotator and extensor that should dominate the squat movement. Insufficient activation forces other, less-efficient muscles to compensate, contributing to the overall imbalance. Additionally, the Vastus Medialis Oblique (VMO), the teardrop-shaped muscle on the inner thigh, is often underactive. The VMO helps stabilize the kneecap and provides medial knee support; its weakness reduces the knee’s ability to resist the inward pull.
Corrective Strategies for Overactive Muscles
Addressing overactive muscles requires techniques that focus on reducing tension and restoring the muscle’s proper length. Self-myofascial release (SMR), commonly performed with a foam roller, is an effective way to inhibit the overactivity of the adductor complex and the TFL. Applying sustained pressure to these tender areas signals the nervous system to relax muscle fibers, improving tissue extensibility. Foam rolling the inner thigh muscles helps release the inward pulling force on the knee.
Following SMR, static stretching should be used to lengthen the inhibited muscles. Targeted stretches for the adductor complex involve a wide-stance stretch, while the TFL is stretched by positioning the hip in extension and adduction. These lengthening techniques increase the range of motion in the hip and thigh, allowing for proper alignment in the squat. Prioritizing the release and lengthening of these tight muscles prepares the body for the activation and strengthening of the underactive stabilizers.