By Paul Oneid
Knee valgus is the term given for an inward tracking of the knees, otherwise known as knees caving, or knees collapsing, and is a common movement fault across all sports. It occurs when the knee begins to track inside the vertical line of the heel and is caused by excess internal rotation of the hip and/or the collapsing of the arch of the foot. In an ideal scenario, the knee should track in a vertical line with the heel. In this position, the proper musculature is engaged, the skeleton is supported and the lines of drive through the body are maintained. Typically, in the sporting world, knee valgus is of special concern because of the increased risk of Anterior Cruciate Ligament (ACL) tears that can occur when the knee is in this position. In powerlifting, the injury risk is greatly reduced, because the feet are in a fixed position and the loading is only in the frontal plane – there is no rotation involved. Once rotation is introduced, such as in certain strongman, or throwing events, the risk of injury skyrockets.
The tracking of the knee is mainly controlled by the interaction of the gluteus medius and the vastus medialis oblique. The gluteus medius is a hip external rotator, while the VMO is a terminal knee extensor. These muscles interact to ensure that the patella (knee cap) remains in an ideal position for the quadriceps (primary knee extensors) to produce force. The tracking of the knee is also controlled eccentrically by the hamstrings (primary knee flexors). During a loaded movement, if these 3 muscles remain properly engaged, the knee should track optimally. This system can fail for a few reasons: strength, position and sequencing. The muscles need to be strong enough, the skeleton needs to be oriented in the proper fashion for them to function and the coordination of the movement needs to be appropriate to load them during the movement.
Muscular strength is an easy fix. If the external loading is greater than the force production capacity of the musculature, the system will fail. Therefore, loading is progressed appropriately over time to allow adaptation to occur. SELDOM IS THIS THE CAUSE OF KNEE VALGUS. In most cases, knee valgus is caused by a loss of position, or an improper loading sequence. If a lift is missed, we want the lifter to maintain their ideal positions, but simply not be able to overcome the external load. Yes, this rarely happens and breakdown is seen somewhere in the chain, but a missed lift with perfect positioning is ultimately the safest way to miss a lift. From a coaching standpoint, this is the toughest way to miss, because it does not direct the training towards a goal and it implies that the attempt improperly prescribed. A technique, or positional breakdown during a lift directs future training towards a goal.
The orientation of the body influences the capacity of the musculature to produce force. In the case of knee valgus, this relates primarily to the position of the feet (if we were discussing the squat, the height of the barbell would influence positioning as well). The ideal position for the feet is completely individual. This is dependent on the limb proportions, shape of the hip joint, mobility capacity across all joints and injury history. If the feet are set too wide, the hip sockets are too shallow and the lifter lacks the requisite hip mobility to externally rotate the femur to a great degree, the knee will track inward and the lifter will not be able to reach appropriate depth in the optimal position to produce force. This is the most common positional fault when it comes to knee valgus – a lifter who is trying to squat too wide for their capacity. If the toes are pointed out too far, optimal force production of the glutes is negatively impacted. If the feet are too close, same issue. Find the foot position that works for you. This may take some experimentation.
The final contributor to knee valgus is perhaps the least acknowledged, but most important – movement sequencing. The loading pattern of the musculature during a movement impacts the ability to absorb and produce force. For a lifter to use a muscle optimally in the concentric portion of a lift, they must load it during the eccentric. An elastic band won’t snap if you don’t stretch it first. Using the squat as an example, we want to begin by bracing the core and hinging at the hip. When doing this, we place the glutes and hamstrings under tension. We then drive the knees out and sit straight down while trying to maintain that tension through the hamstring. This further loads the glutes and as the angle of the knee decreases (descent), the quads are loaded. When depth is achieved, the glutes and quads contract to bring the lifter above parallel, where the hamstrings can be more active and the movement is finished with a strong contraction of the glutes and quads. If this loading sequence is followed, there should be no knee valgus. However, faults can occur and it is important to understand the consequences.
Team PRS member Lisa Guggisberg in Inzer Gripper Knee Wraps
If there is no hip hinge, the eccentric load is place on the quads, instead of the hamstrings. The glutes won’t be optimally loaded either. The VMO will have a greater role in knee tracking, so due to its medial orientation, it will have an internal force on the femur. When loads are light, valgus may be avoided, but when the loads are more challenging the movement flaw will be glaring. If the lifter hinges properly, but does not maintain hamstring tension throughout the range of motion, the knee will track forward excessively in the bottom position. When ascent is initiated, the body will “search” for that hamstring tension and push the hips back. This moves the fulcrum of the movement (hips) further away from the loading vector (vertical line of the barbell). More stress will be placed on the lumbar spine and in many cases with heavier loads, the spine can flex. When the lumbar spine is in flexion, gluteal force production decreases which can allow for internal rotation of the hip and knee valgus to occur. Finally, if the knees are not driving out during the eccentric, more specifically in the bottom position, the knee may travel too far forward and surpass the mobility capacity of the ankle into dorsiflexion. In this position, the arch of the foot will collapse inward to compensate for the lack of mobility. This will decrease the force production capacity of the glutes and possibly lead to knee valgus.
Team PRS member Paul Oneid in Inzer Black Beauty Knee Wraps
When the knees cave in a squat, there are some negative repercussions. Some people may be able to squat in this fashion without any impact to their health, while some may become injured very quickly. As you can see from the above examples, knee valgus occurs when there is a loss in tension somewhere in the muscular chain. That tension doesn’t disappear. It needs to go somewhere. Where the tension typically lands is on the connective tissue. In powerlifting, because there are no forces in the horizontal plane, rotation is minimal and the stress on the ligaments is usually minimal, although ACL/LCL/MCL issues can be seen in extreme cases. In most cases the force falls onto the meniscus, which can tear in this hip internally rotated and knee flexed position. The IT band can also stiffen/ hypertrophy/ shorten to bolster that lateral line of the thigh. This can cause a lot of inflammation and IT band syndrome. This is usually accompanied by patellar tendinopathies from repetitive improper knee tracking under excessive loads.
The overreaching point is this – muscles are meant to support load, not connective tissue. While you may not immediately notice the ramifications of a movement fault, the effects can be chronic. Droplets of water can chew through rock over time. Think of every poor loaded movement pattern as a droplet of water and your joint integrity as the rock. You’re better off to stop the leak before it becomes a flood.