As I mentioned in Monday’s email, today I’m going to breakdown one of the most prevalent myths in existence in the fitness/training world.
I first heard this one when I was in my first year at the University of Waterloo and was working as a volunteer in the physio clinic on campus.
“Keep your knees behind your toes.”
This is often cued during lower body movements, especially squats and lunges.
First, let me present to you Exhibit A, which are pictures from athletes in a wide variety of sports in intense action. Please direct your attention to the position of their knee relative to their toe:
This isn’t unshakeable evidence to destroy the myth but my point in sharing these images is to illustrate the fact that the knees going in front of the toes is a position that athletes will find themselves in.
When I was training pro MMA fighters full-time one of the things I’d say to all my athletes was, “I’m going to take your body beyond what you might experience in a fight because if the first time you experience an intense level of fatigue or muscular or lungs burning is in a fight, it’s not gonna be pretty.”
Now don’t think this just applies to athletes – the next time you go up or down stairs, notice where your knees go relative to your toes!
So if you never train your body in this range, how do you think it’s going to respond when you enter this range at full speed in sport?
Oh and don’t forget – USE IT OR LOSE IT!
Biomechanically, it’s actually beneficial for your knees to go in front of your toes when you do lunges or squats. And with some people with particularly long femurs, necessary to squat to a reasonable depth.
Here’s a relative ROM comparison of the knees behind the toes myth vs. allowing the knees to translate forward during a back barbell squat exercise:
As you can see, to achieve the oft-prescribed “hips just below knees” squat depth, if you try to keep your knees from going in front of your toes here’s how the biomechanical requirements differ:
- Greater hip flexion (hinging), requiring greater lumbar extensor activation and potentially greater shear on the lumbar spine because of the force vectors resulting from the barbell on the shoulders effect on the lumbar spine (this makes any muscular activation error of the deep and superficial lumbar stabilizers potentially dangerous)
- Lower knee flexion with a higher hamstring:quad activation ratio, potentially decreasing knee joint compression forces while increasing shear forces
- Lower ankle dorsiflexion and less potential to drive through the forefoot (aka metatarsal pressure, which all my Lower Limb Controllers know all too well as you’re forced to drive predominantly through the heels, which is another myth we’ll discuss in a future installment
A 2003 study corroborates these points, as they found when keeping the knees behind the toes results in 28% greater knee stress and 1000% greater hip stress and they concluded that, “Although restricting forward movement of the knees may minimize stress on the knees, it is likely that forces are inappropriately transferred to the hips and low-back region. Thus, appropriate joint loading during this exercise may require the knees to move slightly past the toes.” 
The question then becomes, “Is 28% greater knee stress worth 1000% greater hip stress?”
I’d wager both of my knees that it is NOT.
While the hips are a larger joint with more and stronger muscles, 1000% is a lot to absorb versus 28%.
The last bullet point with respect to ankle dorsiflexion is an important one because it’s a range many adults have lost and if we’re at least using our full range by allowing our knees to travel in front of our toes, we’re going to maintain that range.
It’s also funny because people with limited ankle dorsiflexion are forced to put 2.5 pound weight plates under their heels to safely achieve greater squat depth!
Ironic and hilarious, no?
Now, if you’re doing a squat or lunge by only flexing the knees because your hips are as stiff as a wet glove left out in the heart of winter (my Northern climate friends should appreciate this analogy) then trying to get the hips moving as much as possible by keeping the knees behind the toes may be helpful, but this phase should only last up to 8 weeks, because hip mobility for this individual should be a top priority as opposed to adopting a less functional movement pattern.
After that, it’s time to train and program the most efficient M/AP possible for any given movement.
And this is what we do here at Precision Movement with our Control series of courses, which is to first restore adequate mobility, then progress to functional, multi-joint and closed chain movement that transfers to the gym, sport and the movements of everyday life.
To those of you who are have completed or are currently enrolled in a Control course, thank you for your trust in us and commitment to improving yourself. We truly appreciate both.
To those of you who have not yet experienced what it’s like to attain full control of a joint, I invite you to signup for whatever area you think needs the most help, whether Spine, Hip, Shoulder or otherwise – the experience of reclaiming lost ranges of movement and restoring the strength of atrophied muscles is addictive and once you get a taste you’ll want to do the same for every part of your body.