Knees Over Toes Is Not Only Safe, But Necessary

We’ve all heard it: “Don’t let your knees go over your toes!”. 

Often touted by well-meaning trainers, physios and coaches in the context of lunging or squatting, this recommendation is based on the idea that the anterior (or forward) translation of the knee over the toes will place undue stress on the joint, rendering one more susceptible to injury. While the first part of this statement is true (certain structures in the knee are indeed loaded more as the knee goes over the toes), the notion that this will lead to injury and is therefore something to be avoided or feared is absolute folly! In fact, incorporating exercises with this knee over toe moment into your program is a great way of strengthening your knees and reducing your risk of injury- especially in a sporting context. 

Firstly, let’s discuss the way knees over toes is a very normal movement, and certainly nothing to be demonised or feared! You move your knees over your toes hundreds of times a day without thinking about it. Going up and down stairs? Knees over toes. Bending down to tie your laces? Knees over toes. In fact, when you’re done reading this blog, you’ll stand up and your knees will go over your toes. It’s a natural position/movement, so why are we so worried about it? 

The old wives’ tail originates from a 1978 Duke University study that found maintaining a vertical lower leg as much as possible during a squat reduced shearing forces on the knee, leading researchers to recommend trainees squat to parallel and no further. In 2003, University of Memphis research confirmed that knee stress increased by 28% when the knees were allowed to move past the toes while performing a squat. The study also found, however, that restricting forward movement of the knees during a squat increased hip stress by nearly 1000%! 

So, what actually happens when we allow our knees to go over our toes? Well, it’s true that there is an increased torque (rotational force) and shearing force placed on your knees. In this case, torque refers to the force applied by your quadriceps eccentrically controlling knee flexion, or concentrically producing knee extension. In healthy people, however, these forces are greatly below the body’s capabilities; meaning, your knees can handle it. This is especially true when the movement is slow/controlled, and low-resistance/bodyweight. 

Now, let’s talk biomechanics and squatting under load. When it comes to barbell squats, you’re aiming to maintain your centre of mass over your midfoot. Based on this, both your anatomy and the position of the bar will influence back angle and anterior knee translation. As you can see in the image below, during front squats (left) the knees travel further forwards than with low-bar back squats (right). With this, the quadriceps have a larger moment arm and are able to produce more torque around the knee. This does indeed place more load through certain structures at the front of the knee (the patellofemoral joint, the patella tendon, and the quadriceps tendon), however that’s not something to be concerned about! 

Bar position largely determines back angle and knee translation while squatting. Note the bar remains over the midfoot in each case. (Via Rippetone and Kilgore)

As with anything, your body’s ability to tolerate a given movement depends on the capacity of the tissues involved. So yes, if the muscles around your knee aren’t quite developed enough to stabilise the joint and diffuse the forces associated with a movement (especially one that is repetitive, high velocity, or heavily loaded), you may pull up with sensitivity, pain, or injury. However, that doesn’t mean the movement or position is inherently bad or ill-suited to you. Generally speaking, with adequate training you can build tissue capacity to be able to tolerate these forces without any problem! This is the beauty of progressive overload, and training adaptations.

Now, let’s apply these principles to an athlete. For example, a basketball player. Throughout the course of a game, the player’s knees will travel over his toes (at high velocity and with significant force) many times. If the player is restricting his knees from coming over his toes during training, it’s virtually impossible for him to build the capacity in surrounding tissues necessary to tolerate this force, and he’s very susceptible to injury on the court. In order to give himself the best chance of remaining injury-free, the player should be emphasising knees over toes in the controlled environment of the gym. With functionally specific exercises, the player can develop strength in the muscles that surround, support and offload the knee during movement, and improve neuromuscular control to engrain safer, more optimal movement patterns. 

So, in summary, knees over toes is a natural and safe movement. It’s something you’ll do many times throughout the day, especially if you’re someone who plays sport. To give your body the best chance of remaining injury free, you should be incorporating this movement into your training rather than shying away from it. That way, you build strength and develop motor control through this functional range of motion.