On the last post of this series I discussed the myth of ‘Not letting your knees go past your toes when you squat.’ You can view that here.
This week, we’ll be talking about the myth of the importance of the vastus medialis oblique (VMO).
Even as a student, I realized this myth still entrenched within the field of physical therapy. All of my clinical instructors, with the exception of one, emphasized the importance of this area of the quadriceps.
As a student, you should always keep an open mind and be respectful to your CI’s. But, as a clinician, you should also seek to constantly grow. There are a lot of things I believed in a year ago that I don’t believe in now. That’s because I researched and changed my opinions based on what the evidence revealed.
With that being said, I believe there is no evidence to suggest that concentrating on the VMO is useful. Additionally, I believe some of the ways clinicians often attempt to isolate (unsuccessfully) the VMO can actually be deleterious.
How it Probably Started
In a biomechanical study from 1968, it was indicated that fibers of the VMO ran at approximately a 50 degree angle from the long axis of the femur. It was, therefore, thought that these fibers could counter-balance the lateral subluxation of the patella and focusing on this muscle region presumably (I was born in 1988 so I don’t really know) became a focus of the physical therapy field.
John Snyder wrote a fantastic, much more detailed, article on this subject. The image below is from his blog post.
With that being said, there are three main questions I would like to dive into.
- Is the VMO selectively atrophied in individuals with patellofemoral pain?
- Is it possible to preferentially activate the VMO compared to other regions of the quadriceps?
- Can methods to (unsuccessfully) preferentially activate the VMO actually be causing more harm than good?
Is the VMO selectively atrophied in individuals with patellofemoral pain?
A 2015 study, published in the Journal of Orthopedic and Sports Physical therapy, demonstrated that among 70 individuals with patellofemoral pain, there was no selective atrophy of the VMO compared to other areas of the quadriceps. But that there was significantly decrease in cross-sectional area of ALL muscles that comprise the quadriceps when comparing the symptomatic limb to the individual’s asymptomatic side (Giles, 2015)
Is it possible to preferentially activate the VMO compared to other regions of the quadriceps?
In 1995, an EMG study that compared quadriceps exercises with modifications that included variations in hip and tibia position, only one exercise demonstrated a higher VMO/VL ratio. This was terminal knee extension (like a SAQ) with internal hip rotation compared to external hip rotation. But the difference in this ratio was only 0.2. In my opinion (and I’m far from an expert on fine wire EMG studies), this would likely not be clinically significant.
I also think it’s funny that most therapists that believe you can preferentially activate the VMO, do so with hip external rotation. That’s even less supported by this study.
Additionally, no exercise that combined hip adduction with knee extension, like when you see therapists having patients squeeze a ball between their knees and performs LAQs, increased the VMO/VLO ratio (Cerny, 1995)
Those are the two areas I wanted to highlight the most because they are articles I’ve read entirely.
Two of my favorite physical therapy websites also have posts regarding the lack of research for isolating the VMO. These posts contain information, and references, regarding additional information such as the inability to preferentially hypertrophy the VMO, the lack of association with improved long-term outcomes, and about how VMO transection (in rats) does not even. alter patellofemoral joint contact forces.
Can methods to (unsuccessfully) preferentially activate the VMO actually be causing more harm than good?
I think so.
Without looking at individuals studies of the VMO, I also believe it makes sense that certain ways of attempting to isolate the VMO can even be harmful.
Specifically, putting a ball between a patient’s knees and having them performs squats, wall slides, or bridges is essentially teaching hip adduction and IR during hip/knee extension. That’s called dynamic knee valgus and is usually something we seek to avoid.
If you want to externally rotate your hip during a straight leg raise (not a good quad exercise anyway), knock yourself out. But I would seriously stop putting balls between patients knees and telling them to squeeze it when they squat. I’ve seen this from more than one clinician within the past 2 years. I don’t know of any studies to confirm this technique’s deleterious effects but it certainly does not make sense.
If you disagree, I would love to hear your opinion and read research, that I may not be aware, of to support your claims.
- Cerny, K. (1995). Vastus medialis oblique/vastus lateralis muscle activity ratios for selected exercises in persons with and without patellofemoral pain syndrome. Physical therapy, 75(8), 672-683.
Giles, L. S., Webster, K. E., McClelland, J. A., & Cook, J. (2015). Atrophy of the quadriceps is not isolated to the vastus medialis oblique in individuals with patellofemoral pain. journal of orthopaedic & sports physical therapy, 45(8), 613-619.
- Lieb, F. J., & Perry, J. (1968). Quadriceps function: an anatomical and mechanical study using amputated limbs. JBJS, 50(8), 1535-1548.