Debunking the "Knees Can't Cross the Toes" Myth in Squats: A Functional Fitness Perspective

If you've spent any time in the fitness world or followed any workout trends, you’ve probably heard the phrase, “Don’t let your knees pass your toes during a squat.” For years, this advice has been handed down by trainers, physical therapists, and fitness enthusiasts alike. It’s been a part of the “perfect squat form” mantra, and for some, it’s been seen as a golden rule to avoid injury.

But here’s the truth: the idea that your knees should never cross your toes during a squat is an oversimplified, outdated myth. In reality, allowing your knees to move past your toes can be perfectly safe and even necessary depending on your body, your squat technique, and the specific goals of your movement.

At The Impact Initiative Physical Therapy and Performance, we often see the confusion surrounding this common piece of advice. So let’s take a closer look at why the knees-can’t-cross-toes rule doesn’t hold up—and how to approach squatting in a way that’s both safe and effective for your body.

What Happens When You Squat?

When you perform a squat, several factors come into play: hip flexion, knee flexion, ankle mobility, and trunk stability, among others. The goal of a squat is to lower your body with control and maintain a solid posture throughout the movement. This involves coordinating multiple muscle groups, particularly the quadriceps, hamstrings, glutes, calves, and core.

The Myth: Knees Shouldn't Cross the Toes

The origins of the “knees can’t pass the toes” rule stems from a desire to prevent excessive force on the knees. This makes sense if we look at squat mechanics from a very narrow lens—focusing purely on the knee. According to Effects of Knee Position on Hip and Knee Torques During the Barbell Squat (Fry AC, Smith JC, Schilling B.K.), when we do not perform a full depth squat, there are "decreased forces on the knee by 22% and increased hip torque 1070% and increased torso inclination."

In truth, however, there are many factors that influence squat form, and the knee’s position relative to the toes is just one piece of the puzzle. Restricting the knee’s ability to move forward can result in poor squat mechanics, and an increase in force on the hips and low back.

Why the Myth Doesn’t Hold Up

Ankle Mobility Plays a Key Role One of the main reasons the “knees-can’t-pass-toes” rule doesn’t always work is that ankle mobility is a huge factor in squat depth and form. For people with limited ankle dorsiflexion (the ability to bring the foot upwards towards the shin), keeping the knees from passing the toes would require the torso to lean excessively forward, increasing stress on the lower back. Instead of overcompensating with a forward lean, letting the knees move forward—if done in moderation—can actually allow for a more upright torso and reduce undue pressure on the spine.
If you have limited ankle mobility, our Physical Therapists can help you to address these limitations.
Individual Anatomy Matters Every body is different. The length of your femur (thigh bone) relative to your tibia (shin bone), the shape of your hip joint, and your overall body proportions all influence how your squat looks. Someone with longer legs relative to their torso might naturally have knees that pass the toes as they squat deep, while someone with shorter legs may be able to squat without allowing the knees to pass the toes.
Rather than adhering to a rigid, one-size-fits-all rule, it’s important to learn how your body moves and adjust your squat mechanics accordingly. A squat that works for one person might look different from what works for another.
Squats Are Functional Movements Squatting is a functional movement pattern that mimics real-life activities, such as bending down to pick something up or sitting and standing from a chair. In many of these tasks, the knees naturally move past the toes—whether it’s during a deep squat or as you lean forward to grab something from the floor.
Restricting your knees from passing your toes can result in less effective functional movement patterns and, over time, could lead to compensations in your hips, knees, or back. If your knees never cross your toes during a squat, you're potentially sacrificing depth and range of motion that may be important for optimal functional movement and performance.
It’s Not Just About the Knees The most important aspect of a squat is ensuring that you maintain good overall form. This means keeping your weight evenly distributed through your feet, maintaining a neutral spine, and activating the appropriate muscles in the hips, core, and legs. Focusing too much on the position of your knees can distract from these key elements of the squat, leading to a less effective and potentially risky movement.

How to Practice Safe Squatting

If you’re uncertain about your squat form or experience discomfort, click the link below to book a FREE discovery call with one of our Physical Therapists. They can assess your mechanics and help guide you to better movement patterns.

Conclusion

In the world of fitness, the knees-can’t-cross-toes myth is just that—a myth. While the idea of preventing excessive knee travel may have been popularized to promote safety, it’s not a universal rule. In fact, for many individuals, allowing the knees to move forward during a squat is not only natural, it’s beneficial for maintaining a more upright torso and achieving better squat depth. The key is not to follow one rigid rule, but to focus on proper movement mechanics, individual body structure, and mobility.

At our clinic, we believe in helping you move better, feel better, and perform better—no matter your fitness goals. If you’re ready to optimize your squat form, address mobility limitations, or train for better overall movement, The Impact Initiative Physical Therapy and Performance is here to help. Click the link before to book a FREE discovery call and meet your goals!

Citations: 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.

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