The pre-exhaustion technique using leg extensions before squats is an old school bodybuilding technique that has been used for decades by some of the best bodybuilders in the world. Just make sure to use smooth mechanics on the leg extensions and eliminate momentum in order to avoid placing too much stress to the knees.
 

The Problem with Sissy Squats

It doesn’t take an expert in biomechanics and functional anatomy to realize that the stress placed on the knee joint during sissy squats is less than ideal as the weight is shifted excessively and unnecessarily forward into the knee joint. 

Yes, some folks who’ve been blessed with genetically resilient knee joints can get away with these. However, just because an individual can get away with a movement doesn’t mean it’s ideal or optimal.  If, in fact, dysfunctional and aberrant mechanics are employed during a movement (which one could argue is the case with the sissy squat), eventually there will be consequences. 

As I’ve stated multiple times in various posts “Poor mechanics is like smoking. It can take anywhere from months to decades before the consequences are felt. Eventually it does affect your health and quality of life. It’s just a matter of time.” Read more about Pain Science & Body Mechanics here.

So yes, generally speaking I don’t recommend consistently performing traditional or even modern day variations of the sissy squat movement as I believe there are far safer and more effective movements. Additionally, when it comes to understanding functional movement and optimal biomechanics for the human body it could be argued that the sissy squat is highly dysfunctional as in no way shape or form does it represents a movement we would ever do in everyday life or sports particularly under perfectly vertical force scenarios. In fact, if we were to observe an athlete assume such a position during sports or athletic events on a consistent basis we would consider that very poor biomechanics and a very un-athletic movement in need of a serious overhaul.
 

The Truth About Knees Over Toes

One of the biggest debates currently trending in the fitness industry is the question of whether allowing the knees to move in front of the toes is dangerous or not. In reality, there’s nothing wrong with the knees going past the toes in terms of anterior knee drift with the caveat being that the force vectors of the body must match the incoming force vectors of the movement/environment.  

Simply, it’s not so much about knee position (i.e. knees past toes) as it is a question of where the force vectors are coming from. For instance, all of the squat variations shown in this article, performed on the toes or the balls of the feet, include both vertical and horizontal force vectors (i.e. angular forces), similar to going down the stairs or during certain forward athletic movements (i.e. acceleration). In such scenarios the knees will, and oftentimes should, move past the toes. The key here is to match up our force vectors with the incoming forces. 

If you were to take snapshots of any of the squats shown in this article, rotate the image 30-45 degrees, it would look nearly identical to a traditional squat as they would illustrate the same joint mechanics and positions as traditional 90-degree squats, with proper joint stacking of the ankles, knees, and hips. And although the lifter would be on their toes their ankle or shin angle would be no different than a traditional squat (i.e. the degree of dorsiflexion would be the same). Instead, they would have shifted every component of the squat equally to match the incoming force vectors. In such instances there would be relatively equal joint stress across the hips and knees while simultaneously placing greater tension on the muscles of the quadriceps. 

In contrast, when we allow the knees to move past the toes during a traditional squat where there’s only vertical force vectors, we’re now producing a horizontal force vector against a primarily vertical force, which represents a mismatch of force vectors. This not only compromises force production and absorption, it also places undue strain on the joints and connective tissue as the muscles are in a biomechanically disadvantageous position to absorb and produce force. The same is true of a lunge or split squat.

With that said attempting to sit back into the heels and minimize anterior knee drift by not allowing the knees to travel forward on any of the squats shown in this article not only feels very unnatural but it actually places even more stress on the knees.  That’s right, trying to inhibit the knees from going forward during movements such as those shown in this article is actually just as dangerous and counterproductive as attempting to produce excessive anterior knee drift during movements that involve perfectly vertical force vectors such as traditional squats. 

In fact, I can tell you from personal experience having experimented with the movements I highlight in this article, attempting to eliminate anterior knee drift and inhibiting the knees from traveling past the toes feels miserable on the knees not to mention very unnatural and dysfunctional.  Therefore, it is quite obvious that the question of “knees over toes” being good or bad all comes down to the context and is predicated on whether or not there is a matching or mismatching of force vectors.

When force vectors are matched, performing a movement with the knees traveling significantly past the toes and shifting weight to the ball of the foot is not only extremely functional and transferable to athletic performance, it’s also a tremendous quad and thigh builder. It’s also a great way to strengthen the connective tissue around the knees while simultaneously ensuring the muscles are doing their job of absorbing force in the most effective and efficient manner. 

In contrast, attempting to force the knees past the toes when force vectors are mismatched, is not only a subpar strength and hypertrophy stimulus for the quads, or any muscle, it’s potentially dangerous on the knee joints not to mention it reinforces dysfunctional movement patterns into the CNS that are likely to transfer to other movements and ultimately compromise athletic performance and quality of movement.  Read more in my book MOVEMENT REDEFINED.

If You Insist

If you insist on performing sissy squats and feel they work well for your body there are several recommendations I would make.

1. Don’t go beyond 90 degree joint angles at the knee.

2. Stop performing them if you feel any pain or discomfort.

3. Minimize the volume and simply use 1-2 sets as a quad finisher.

What About the Sissy Squat Machine