Knees should not pass tiptoes… BULL**IT!

I have heard many times that the knees should not go past the top of the feet or that squats performed with the knee bent high (all the way down) cause pain, and for me, these two “myths” are closely related and can cause more problems with posture and biomechanics, unless we do the opposite.

In today’s article, we will talk about each one separately and we will see if they are as dangerous or as wrong as some people claim!

The fear of performing a squat with the knees over the top of the feet revolves around the idea that the ligaments/tendons will jump out of place.

A valid argument, that’s why we have to see what forces can cause problems: when we squat, two types of forces are applied to the knee: shear force and compressive force.

Shear forces refer to how much two bones slide over each other, in this case, the femur and the tibia, and this type of pressure could be dangerous for the ligaments ( ACL, PCL ).

ACL – anterior cruciate ligament

PCL – posterior cruciate ligament

*A secret, bones work ONLY by rotation!

Compression forces refer to the pressure created when two bones press against each other, this type of pressure affects the meniscus more, which has the role of absorbing the force.

*Another secret, the bones never TOUCH!

Now that we have determined the “dangers”, we have to see what the specialized literature says. People fear or have been taught that the knees should not go past the tops of the feet/do not go below 90 degrees, all because of some studies from the ’50s that have spread over time and entered so strongly in the minds of some trainers that, even after they were dismantled and a lot of studies appeared that show the complete opposite, it is still practiced.

Returning to the pressure applied to the ligaments, we must know that the greatest pressure applied to the LIA is when the knee flexion angle is somewhere between 15-30 degrees (at the beginning of the movement), and the lower we go, it decreases due to the shearing forces which no longer stresses the ligaments. Interestingly, during squats, the maximum force applied to the ligaments is only 25% of their maximum breaking capacity. In the case of LIP, the force applied during the movement is 50% of the maximum capacity.

In other words, the body is a much more resilient system than we think!

If we talk about squats, the only “problem” could arise due to the compression forces that increase when we are at the bottom of the squat, but even here the evidence is small or even non-existent. If these theories were true, then most people who lift weights, especially weightlifters or powerlifters, would suffer from constant problems, which is untrue.

In addition to these, squats with a high flexion of the knee (ass to grass and knee over toes) create a greater degree of stability, this is also said by studies where knee stability was measured in powerlifters, runners, and basketball players after the end of the effort (an hour of playing on the field, running 10 km and squatting). At the end of the measurement, the highest degree of stability was found among the powerlifters. This is another reason we must introduce squats in the training program and give up the outdated and wrong concepts!

Before moving on, we have to summarize: the body’s superpower is the fact that it adapts! This means that both tendons and ligaments become stronger when we expose ourselves to forces!

When performing squats, it is necessary to follow some indications that apply, regardless of the anatomical construction: VERTICAL TRAJECTORY OF THE PELVIS, the bar/weight moves on a vertical line above the middle of the leg, the knees are in the extension of the tips, the sole is completely on the ground.

Here we must remember that there may be small differences or changes that we create depending on the anatomical construction of each one (femur length – short/long, trunk long compared to the legs, joint capsule depth – deep/superficial, anteversion/retroversion), all to respect the genuflection pattern.

“Why do the knees go past the tops of the feet?”

“I still don’t understand!”

Here comes the circular arc (Limb Arc) which tells us that any movement we make happens in a 3D space, and to access certain amplitudes, the skeleton must change its shape.

In other words, during a squat, we go from external rotation to internal rotation and back to external rotation.

Let’s talk a little about each stage:

Zone 0-60 degrees

Here we are talking about the bones of the pelvis and the femur, tibia, and foot. All must rotate externally to be able to start moving.

Area 60-90 degrees

The area where the knees MUST go over the tops of the feet to maintain the vertical trajectory of the pelvis. Here the skeleton rotates internally to be able to stop the weight approaching the ground. Think of knees going inwards.

Area 90-120 degrees

Here we are again talking about the external rotation of the femur, pelvis, and foot to be able to access the last part of the movement. Here the knees must move backwards, not forwards.

Everything I wrote above follows only one thing, the VERTICAL TRAJECTORY OF THE PELVIS.

We must remember that the knees MUST move forward to be able to go below 90 degrees and maintain the correct trunk position during the movement.

As a summary: the knees MUST go over the tops of the feet, what is important is WHEN this happens!