I've been doing split squats lately, partly to help strengthen my VMO

I've read in a number of places that you should track your front knee over your toes in order to place more load on your VMO.

But this goes against a lot of other advice I've read or been told in the past, that you should never let your knees go past your toes with any leg exercises... and that doing so would leave you prone to injury.

Is there just some sort of exception with split squats or something?

1 Answer 1


The origin of the old dictate of keeping the knees behind the toes is unclear. Wherever it came from, however, it subsequently became the standard dogma within general fitness circles—a dogma that persists to this day. The notion likely stems from observations that patellofemoral compressive loads increase with the depth of the squat. And since untrained individuals also tend to lack the mobility to achieve a full (or deep) squat, their attempting to do so, therefore, necessarily compromises other aspects of its safe performance.

However, the doctrine ignores the fact that it is entirely natural to squat to full depth, and that in order to do so, the knees must travel a considerable distance past toes. Indeed, for a very large subsection of the world's population, full squatting is a part of daily life. And elite weightlifters routinely and safely squat to full depth with enormous relative and absolute loads. (See below.) Furthermore, keeping the knees behind the toes unnaturally increases the joint moment in the knee, as well as increasing compressive and sheer forces on the spine.

enter image description here

There is some justification for the advice that you have been given: the vastus medialis oblique (VMO) does indeed appear to be more active in deeper squats, although we might have reason to question the choices of knee angles (20°, 50°, and 80°) investigated. But whilst I am not an expert in remedial exercise, my memory is that the VMO is most effectively activated by squatting with a shallow knee bend, performing an isometric squeeze at the top of the range of motion. And this notion is supported here. Interestingly, it is the trailing leg of the split squat (a split jerk is shown below) that approximates this motion. And it is standard in the split squat to encourage the lifter to distribute the load evenly between the legs, thereby requiring a more vertical tibia. But, as I hope my earlier discussion demonstrates, there is nothing fundamentally wrong with allowing the knee to pass the line of the toes.

enter image description here

I hope that is helpful.

  • Thank you for your answer... with regards to the trailing leg in the split squat, are you saying that this would work the VMO? or would that be more with the front leg?
    – user33566
    Aug 9, 2020 at 9:22
  • 1
    @RR88: Possibly, yes. I deliberately chose an image of a weightlifter (in this case Lidia Valantín) with a particularly straight trailing leg. I know of no specific research that verifies this idea, but it is consistent with the paper above which suggests that micro-squats activate the VMO well. And that exercise approximates the types of exercise that are often prescribed by sports doctors and physiotherapists to engage the VMO. (I am not an expert in rehabilitation, but that seems consistent with what I know of the subject.)
    – POD
    Aug 9, 2020 at 10:30

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