You've probably heard the cue: “Don’t let your knees go past your toes in the squat.”
This is bad advice.
It’s also one of the most pervasive misconceptions in the world of fitness and it has significant negative effects on the body.
Squat With Knees Past Toes
Doing deep squats in which your knees go past your goes toes protects the knee, strengthening connective tissue that allows you to move pain free. Deep squat training involves something known as "the wrapping effect," which allows for enhanced distribution of the load over the knee joint.
There's also evidence that deep squats reduce inflammation in the knee joint. Regularly loading the knee with full-range motions improve synovial fluid, which has a therapeutic effect on the knees.
Why Keep You Knees From Going Past Toes Is Bad Advice
When you restrict the forward motion of the knee and don’t let it pass over the toe in the squat two things happen:
First, keeping the knees from going past the toes in the squat makes you bend forward more, which puts greater stress on the lower back. This increases risk of injury or pain. Keeping the knees from passing the toes in the squat is a key reason more and more people are developing back pain.
Second, restricting the knee means you can’t squat as deep. You can only squat down to about parallel when you restrict your knees from going past the toes. Even that depth is only reached if you are very flexible in the hips.
It just so happens that the part of the squat that places the highest compressive force on the knee is at a 90-degree flexion angle where the thigh is parallel to the ground. As you squat lower, the contact between the back of the thigh and the calf reduces the knee-joint forces.
Knees Past Toes Is A Natural Motion
There are numerous natural motions in everyday life when the knee must pass over the toes:
- Every time you walk up or down the stairs, the knees pass over the toes. Try restricting this motion and you’ll notice that it puts a lot of pressure on the hip, and is very inefficient. Training full squats can help prevent knee pain associated with stairs so that you can navigate them with grace.
- Picking objects up off the ground is a necessary motion of daily life. Bending over from the waist is a huge no-no because it puts incredible pressure on the lower back. Going into a deep squat and lifting with your legs is a much safer motion. Unrestricted squats train you to do this safely.
- Many motions in athletics from pivoting to sprinting to bicycling require the knees to pass the toes. Strong and healthy knee and ankle joints are necessary to avoid injury and optimize performance. Training heavy full-range squats can get you where you need to be.
Finally, consider that the athletes with the healthiest knees are those who regularly perform full-range, unrestricted squats in their training:
Weight lifters who perform the clean and snatch and go into a deep squat at the finish of these exercises have a very low rate of knee injury.
The Bottom Line:
Restricting the knee motion of the squat places increased stress on the knee and hip, while putting the lower back at risk. Further, keeping the knees from going past the toes during squats is less effective for training strength in the muscles surrounding the knee and ankle joints. To optimize lower body strength and power, full-range, unrestricted squats are the way to go.