Among the various mechanics and form cues of the squat movement, one often repeated in error throughout much of fitness-related literature is to always keep one’s knees over their toes, never allowing the knees to surpass the toes vertically so as to prevent injury.
This is not entirely true, as further studies involving joint torque and force reveal that doing so may even be detrimental for certain exercisers, thus making this particular form cue dependent on the exerciser’s own comfort.
Keeping the knees over the toes during a squat is an outdated cue that nonetheless still holds some amount of truth to it - allowing exercisers to use it as a sort of “soft rule” that can aid in their adherence to safe and proper squat form.
This particular form cue is performed exactly as it is named; with the exerciser ensuring that their knees never surpass their toes perpendicularly in a horizontal plane. If needed, one may imagine that they are squatting with the tips of their toes touching a wall, preventing the knees from extending beyond that point.
This is meant to ensure that the exerciser equally distributes the load and pressure of the squat between their hips and knees, as well as to reduce total torque force placed on said knee joint.
However, this has been partially disproven, as it has been noted that the force tolerance of the knees is more than sufficient enough to allow for them to bend forward beyond the toes, so long as certain other form cues are properly met as well.
Such a technique is also at odds with the fact that the exerciser must reach an appropriate squat depth at the bottom of the repetition, forcing the knees past the toes. Failing to reach proper squat depth as a consequence of adhering to this particular form cue can result in injury or reduced total training stimulus.
As an added note, preventing the knees from bending forward beyond the toes must not be confused with a similar form cue wherein the knees are meant to maintain alignment with the ankles and avoid caving inwards - a serious form error known as knee valgus.
As was mentioned in the previous section of this article, keeping the knees over the toes while squatting is wholly unnecessary, though it must be noted that doing so to an excessive degree should generally be avoided as this breaks proper squat form by forcing the pelvis forward.
Otherwise, no; keeping the knees aligned vertically with the toes is not necessary, though it does indeed reduce pressure placed on the front of the patellar joint, making it a useful cue for individuals with a history of injury in that particular area.
The main benefit and primary reason this particular form cue is even still utilized in modern lifting is the fact that it does indeed shift pressure and loading demands to other parts of the body than the knees.
However, the caveat to this is that, if the knees move past the toes, the sort of pressure and force applied to the knees is not otherwise damaging unless the exerciser is utilizing far too much weight or is not performing the exercise with correct form.
As such, while keeping the knees over the toes is technically correct in its purpose, there is no need to do so save for specific situations or conditions that require it.
There are several key disadvantages to always keeping the knees over the toes during the squat, the first of which is the fact that it can shift great amounts of force to the lower back and hips if the exerciser is of insufficient flexibility.
Such a disadvantage is in combination with the fact that, also due to mobility requirements, keeping the knees over the toes can reduce total range of motion and squat depth, thereby reducing the effectiveness of the exercise and increasing the risk of injury in other joints of the body.
Finally, there is also the fact that obeying this particular rule of the squat may be incompatible with individuals that possess particularly long femurs and short shins, changing their biomechanics to one that makes keeping the knees over the toes nearly impossible without bending the torso forward as well.
If the exerciser wishes to adhere to this particular form cue and always keep their knees above their toes, doing so is relatively simplistic, as they need only push the pelvis backwards at the start of the repetition while ensuring that the shins are bent as little as possible throughout the full squat range of motion.
This, of course, is in combination with other form cues that are considered to be vital to the performance of the squat, such as ensuring that the spine remains in a neutral angle, that the feet are pointed in an outwards direction, and that the knees do not cave in towards one another.
One must also keep in mind that certain variations of the squat make keeping the knees over the toes difficult to maintain without losing balance, excluding these particular exercises from this specific form cue.
In order to achieve a complete range of motion that entails an effective squat, the exerciser will need to move their knees beyond their toes at the bottom of the repetition - and as such, exercisers should generally not attempt to keep the knees over the toes throughout the repetition.
This is not to say that the knees should always be extended forward, however, as proper squat mechanics dictate that the total load and pressure of the exercise should be evenly distributed throughout much of the lower body - and extending the knees beyond the toes shifts this unevenly.
Ideally, the exerciser will begin a repetition with their pelvis thrust backwards and the knees parallel or behind the toes prior to the knees crossing beyond this point the closer the exerciser gets to full squat depth.
1. Hartmann, Hagen & Wirth, Klaus & Klusemann, Markus. (2013). Analysis of the Load on the Knee Joint and Vertebral Column with Changes in Squatting Depth and Weight Load. Sports medicine (Auckland, N.Z.). 43. 10.1007/s40279-013-0073-6.
2. Lorenzetti S, Ostermann M, Zeidler F, Zimmer P, Jentsch L, List R, Taylor WR, Schellenberg F. How to squat? Effects of various stance widths, foot placement angles and level of experience on knee, hip and trunk motion and loading. BMC Sports Sci Med Rehabil. 2018 Jul 17;10:14. doi: 10.1186/s13102-018-0103-7. Erratum in: BMC Sports Sci Med Rehabil. 2020 Jan 29;12:7. PMID: 30026952; PMCID: PMC6050697.
3. Fry AC, Smith JC, Schilling BK. Effect of knee position on hip and knee torques during the barbell squat. J Strength Cond Res. 2003 Nov;17(4):629-33. doi: 10.1519/1533-4287(2003)017<0629:eokpoh>2.0.co;2. PMID: 14636100.