Your knees are designed to bend and travel past your toes.
Stop listening to what your phys ed teacher, coach or trainer said to you in the past. The advice "don't let your knees go over your toes" is by definition, a myth. This is not a radical statement, as it has been proven by science repeatedly.
In this article, I will outline why you should not only allow your knees to travel past your toes during training but emphasize it!
In an effort to keep this as short and concise as possible I will focus on two key points, the science and the evidence.
The Science
In a study conducted in 2003 in the Journal of Strength and Conditioning Research aimed to examine the "Effect of Knee Position on Hip and Knee Torques During the Barbell Squat" Fry, Smith, and Schilling used trained men with at least 1 year of experience using the traditional back squat. They had the subjects perform two variations of the squat. The first, allowed the subject's knees to travel forward past the toes. The second restricted the forward travel of the knee using a barrier. The researchers tested the shearing forces experienced at both the knee and ankle joint in both squat variations.
They found that when knees travelled over the toes it did increase the shearing forces on the knee joint from 117.3 N/m to 150.1 N/m, which is an increase of 28%
This information seems to validate the myth until you look at the shearing forces of the hips and lower back.
The researchers concluded the shearing forces increased from 28.2 N/m to a whopping 302.7 N/m a 1007% increase!
Increased shearing forces on the joints can increase the likelihood of dysfunction, pain or injury.
Inhibiting the knees from travelling past the toes causes subjects to lean further forward for balance and place an enormous amount of force on the lower back which could lead to pain and injury.
"Barbell squat technique should incorporate techniques that optimize forces at all the involved joints" (Fry, Smith, and Schilling, 2003)
Or in my own words...Allow your knees to travel over your toes when squatting!
The Evidence
Now that you understand the science lets look at someone everyone has been talking about lately with the new documentary "The Last Dance". Michael Jordan.
Success leaves clues...
This image illustrates two key points...
The first is that the knee is clearly travelling past the toe. Ask yourself, shouldn't you train the same positions you will be in your sport? Take a close look at athletes in other sports and you will notice the same. The knees travel over the toes all the time.
The second is, Oh my God Ankle Range of Motion! Michael Jordan had insanely flexible and strong ankles. This allowed him to play lower to the ground than his opponents.
Any basketball coach will tell you that the player who gets lower, wins. Their lower centre of gravity allows for quicker acceleration and change of direction and MJ was one of the greatest ever at playing lower to the ground than his opponents.
MJ (6'6) getting lower than John Starks 6'3) and blowing past him. Look at the knees way over the toes!
I don't believe it's a stretch to say this has a major influence in Jordan's athletic ability on the court and his overall success. He even got nicknamed "Black Cat" for his agility and ability to elude his defenders.
And who can argue with the results...
Thank you for reading,
-Matt
References:
Fry, Andrew C, J Chadwick Smith, and Brian K Schilling. “Effect of Knee Position on Hip and Knee Torques During the Barbell Squat.” Journal of strength and conditioning research 17.4 (2003): 629–633. Web.
List, Renate et al. “Kinematics of the Trunk and the Lower Extremities During Restricted and Unrestricted Squats.”Journal of Strength and Conditioning Research27.6 (2013): 1529–1538. Web.
Russel, P.J., And S.J. Phillips. A preliminary comparison of
front and back squat exercise. Res. Q. Exerc. Sport 60:201–208.
1989.