Don’t let your knees go past your toes when squatting
Should you always avoid letting your knees go past your toes when squatting?
We hear this “rule” repeated like a mantra by a great many coaches and fitness professionals: “Don’t let your knees go past your toes when you squat!”
The reality is that there isn’t much scientific evidence to support this claim. It is true that the knees travelling forward during a squat increases the load on the knee joint. But there is no “magic point” beyond which the load on the knee joint suddenly becomes especially dangerous. The vertical plane running up from the toes is often viewed in far too black-and-white a way. Keeping your knees behind your toes is not as clearly dangerous or safe as it is so often made out to be.
There are situations, and individual quirks of the body, bones and joints, in which rigidly never letting the knees pass the toes can actually create additional problems, for example in the other joints that also work during a squat.
This topic was covered quite thoroughly and illustratively by Fry and his colleagues (Fry, Smith & Schilling 2003). They observed seven trained male subjects squatting. For three of the subjects the knees were restricted from moving past the toes, for three they were not. The restriction was, quite literally, a wooden board placed upright in front of the person squatting. As expected, comparing knees past the toes with knees stopping at the vertical plane of the toes, the load on the knee joint during the squat was greater for those who let their knees go past the toes (150 vs 117 newton-meters). That makes it sound as if consciously keeping the knees behind the toes when squatting is justified, a good and right thing to do, doesn’t it?
But let’s not rush
Squatting with restricted knee movement, on the other hand, shifted a markedly greater load onto the hip joints than squatting with the knees allowed past the toes. The difference was as large as 302 vs 28 newton-meters, and in the hip joint’s “favor,” so to speak.
Perhaps even more problematic with these results is that the load shifted onto the hip joint when knee movement was restricted came from having to lean the upper body far forward from the hips to keep balance. The knees don’t go past the toes, but to maintain balance and your center of gravity you have to lean forward quite a lot. Studies have in turn shown that a large forward lean during a squat with heavy weight carries a very high risk of lower back injury. And compared with other joints, the lower back is a very fragile area. So it is not exactly a good trade-off.
So what should you take away for your own squatting, and what is the message of this discussion? Let me quote Fry himself, who sums up the topic quite well: “It is critically important to reduce the excessive forces on the knee joints that come with squatting, but it is also important that the hip joints not come under undesirable load. Too much constant load on the hip joints soon passes on to the lower back in turn. When analyzing the movement, it is important to work out the optimal movement structure for all the joints involved in the exercise. Technique guidelines for exercises (including the squat) should not focus solely on the safety of one joint (the knee joint) while neglecting the injury risk of the other joints involved in the movement (the hips and lower back).”
Original article here: Knees-Past-Toes During the Squat
To be continued…
Related articles:
Don’t let your knees go past your toes when squatting. Myth or reality? Part II
Author: Janar Rückenberg (translation)
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