Why Your Knees Hurt – Valgus Knee Collapse

Chronic knee pain is one of the most common and frustrating issues in both the gym and athletic world. While high impact collisions to the knee are sometimes unavoidable, many knee injuries are largely preventable through superior training and a greater awareness of optimal mechanics.

For today’s post, I’m going to focus primarily on the control and positioning of the knee during movement and why it’s important. In particular I’ll focus on the concept of Knee Valgus collapse and its relevance to the squat. Part two of this blog post series will look at how we can overcome the reasons for valgus collapse in more detail.

What is Knee Valgus Collapse & why is it Important to Avoid?

Knee valgus refers the collapse or caving of the knees inward, typically when the hips are in a flexed position such as during the squat. Here the hip adducts and internally rotates while the knee itself actually abducts and externally rotates. This is a highly undesired position to be in. Why? Knee valgus collapse is a significant contributing factor for knee injuries such as acute ACL (anterior cruciate ligament) tears, plus other more chronic issues such as Patellofemoral (knee tracking) pain and ITB syndrome (illiotibial band). In addition, it can impact movement efficiency during the squat and be more energy costly which will limit performance potential. Thus, we want optimal knee control and tracking, with the knee joint moving down its correct “tracks” just like a train stays on its tracks. Deviate and you’re going to crash causing damage to the knee joint structures. This will even have a flow on effect all the way down to the foot and can cause excessive pronation (though this isn’t the focus in this post).

Why does Knee Valgus Collapse Occur?

It typically occurs due to a combination of strength imbalances and tightness or restriction in key areas. However, it should be noted that some individuals are also more predisposed to valgus knee collapse than others (primarily females). The chief reasons are typically as follows:

1 – Weak Hips 

2 – Tight or Overactive Adductors

3 – Tight Hip Flexors 

4 – Insufficient Ankle Mobility 

5 – Structural Imbalances Around the Knee

6 – Coordination and Technical Errors

Weak Hips

Weak hips, in particular the glute medius will impact the positioning of the femur (thigh bone) and decrease stability at the knee. Simply, weak glutes will allow the knee to drift inwards and be poorly aligned with knee structures. A strong and active glute medius is absolutely integral for optimal squat mechanics and without it you’re asking for trouble. When I first observe knee valgus collapse I’ll typically start here and assess gluteus function before expanding outwards for contributing factors.

Tight or Overactive Adductors 

When the adductor muscles are tight or overactive, this can contribute to the femur rotating inwards. This can restrict the ability to sufficiently open the hips during the squat descent and force a movement compensation to occur to perform the better. The result is suboptimal mechanics and a greater predisposition to injury. Tight adductors can cause a flow on effect throughout the body which can contribute to issues at both the knee and ankle.

Tight Hip Flexors

The concept of reciprocal inhibition states that when one muscle is tight or short it’s antagonist muscle is typically weak. An antagonist muscle is essentially the sister or opposite muscle which must relax during a movement of the agonist, the primary movement driver muscle.

Thus, tight flexors can contribute to the weakness in the glutes (the antagonist muscle) due to a down regulation of neural signalling to these muscles. This problem is commonly pronounced due to the excessive amount of sitting we as a society do on a daily basis. Excessive sitting leads to a constant contraction of the hip flexors, which can lead to a chronic shortening and overactivity of the hip flexors. The end result is often weak glutes as illustrated below.

Poor Ankle Mobility

When an individual lacks sufficient ankle range of motion (dorsiflexion), the other joints are forced to compensate by providing additional movement to complete a pattern. The problem is that the primary job of the knee joint is that of stability and not mobility. Thus, there is commonly a flow on effect whereby the foot goes into pronation (rolling inwards), which causes the tibia (shin bone) to internally rotate, which then contributes to knee valgus collapse. A healthy ankle can typically achieve roughly five inches or ten to twelve centimetres of dorsiflexion. This can be tested using the knee to wall test as shown here.

Structurally Imbalances Around the Knee

Our muscular system is essentially an elaborate system of cables and pulleys designed to work together in unison. However, when one muscle becomes overly weak or strong, the balance within the body becomes distorted which can cause structural issues. The knee joint has numerous muscles connecting to it via tendons and if function and mechanics are poor this can cause control issues. For instance, the Vastus Medialis or VMO muscle (inner quad/thigh) needs to have sufficient strength to work together with the far larger Vastus Lateralis (outer quad / thigh). Imbalance here can lead to “tracking” issues, which can lead to an accumulation of wear and tear before the onset of pain. Other muscles located around the knee such as the Hamstrings and Gastrocnemius can also play a role in knee stabilisation and need to be sufficiently strong as well.

Coordination Issues

Sometimes the problem may not be physical but mental, with the individual simply moving with poor technique. If the individual is able to improve their movement pattern by responding to coaching cues and feedback, coordination would likely have been the culprit. In addition, research has shown that when it comes to cueing and reinforcing the learning process, external cues are superior to internal cues for movements. The external cues help to make the learning “stick” whereby the coaching cue is better understood and remembered. In regards to the squat, “knees out” is an internal focused cue we can use at the bottom squat. While this does indeed work, an externally focused cue such as “open the clam”, which can be condensed to simply “open” is far superior for memory retention. This is important when coaching beginners in particular and the more novel the cue, the more likely it is to be remembered.

Next Up in the Blog Series, I’ll focus more on how to fix these issues.