Identifying the What and Why of Valgus Collapse (Part 2: Identifying the Why of Valgus Collapse)

Published on 1/6/2012 by Dr. Robert Butler in FMS Research

 

Previously, we discussed how valgus collapse is often related to a number of movement related pathologies. The construct of “valgus collapse” has previously been suggested to come primarily from a combination of hip adduction, hip internal rotation and knee external rotation. Now the question begs as to whether valgus collapse is modifiable and if so why does valgus collapse occur? Is it just a strength issue, is it a muscle activation issue, is it a proprioceptive issue or is it something entirely different?

Multiple studies examining valgus collapse have suggested that it is modifiable. Multiple studies have suggested that neuromuscular training programs can reduce the amount of valgus collapse. Reductions in valgus collapse during jump landing have also been observed when using imagery techniques.  The bottom line here is that valgus collapse is modifiable. Now that we know it is modifiable it is important to determine what are the factors associated with this movement dysfunction in order to develop efficient intervention strategies.
The first item that is often thought of to correct valgus collapse is maximum muscle strength. Research on the relationship between strength and valgus collapse has suggested that no relationship exists between these parameters. While maximum strength alone is not related to valgus collapse, it does appear that a component of strength, muscle endurance, is related to hip internal rotation during running (a component of valgus collapse). Souza et al., (2009) reported that the only factor that predicted hip internal rotation during running, when considering multiple lower extremity strength and anthropometric measures, was hip extension (Gluteus maximus) endurance (r² = 0.20).  The results of this study help in understanding what factors are related to 1 of the 3 components of “valgus collapse”. So the question remains as to what else may be related to this movement construct.
The next item that is often discussed when attempting to explain valgus collapse is muscle activation. Little work has been conducted in this area likely due to the delicate nature and difficulty in the collection and interpretation of these data. One study has suggested that an earlier onset of the gluteus medius and maximus were correlated with hip adduction motion while an earlier onset of the gluteus maximus was correlated with hip internal rotation motion during running (Willson et al., 2011). It was interesting to note that the timing of onset exhibited a stronger relationship than peak or average muscle activity of the gluteus medius and maximus during running. However, since correlation does not equal causation it is important to look further into the literature. Follow up studies have revealed that the strongest predictors (Willson et al., CSM 2011; r² = 0.45) of hip adduction during running is the onset and length of activation of gluteus medius. These findings would suggest that neuromuscular training that causes an early onset of the gluteal muscles would be beneficial in optimizing movement retraining as related to correcting valgus collapse.
So to date, the best hypothesis that we have as to how to normalize “valgus collapse” is by focusing on gluteal muscle endurance and pre-activation. It is important to note that both of these studies occurred in during running as opposed to jump landing which may bring about a different model for retraining due to the bilateral nature of the task. I think one question that remains is regarding at what level of resistance does the dysfunctional pattern appear?  Jump landings and running place about 2.5-5 bodyweights on the lower extremity on the body and when our bodies respond with valgus collapse it is not because it is physiologically optimal rather it is due to an inherent need to utilize secondary planes of motion to keep the body upright and to maintain a cranial acceleration of 1 g. If this were a resistance exercise we would simply reduce the amount of weight (i.e. take a plate off or change barbells) to examine under what load the compensatory strategy occurred, however, these are dynamic motions which we cannot offload so easily. This is what we will discuss in our next two postings. How do we breakdown the higher level constructs of running and jump landings to determine at what level dysfunction exists?