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Squat Depth: How Low Should You Go?
- Ryley Humrighouse
- Feb 3, 2023
- 4 min read
Introduction
When it comes to squats, one of the most common questions is, “How deep should I go?” Is it quarter squat, 90 degrees, parallel, or ass to grass? The truth is, it depends. Every person has different goals, anatomy, and mobility that can affect how deep they can and should squat, so we can't answer those questions without knowing you specifically. However, what we can do is provide information on muscle recruitment during squats at various depths to help you decide for yourself. This information is provided by a study done in May 2019, is measured in percent maximum voluntary isometric contraction (% MVIC), and can help you determine the right depth for you.
The Data
Knee Extensors in the front squat (front of the leg):
60 degrees of knee flexion - 32.2% MVIC
90 degrees of knee flexion - 53.1% MVIC
120 degrees of knee flexion - 44.8% MVIC
Hip Extensors in the front squat (back of the leg):
60 degrees of knee flexion - 20.3% MVIC
90 degrees of knee flexion - 34.5% MVIC
120 degrees of knee flexion - 33.2% MVIC
Knee Extensors in the back squat:
60 degrees of knee flexion - 35.5% MVIC
90 degrees of knee flexion - 59% MVIC
120 degrees of knee flexion - 62.4% MVIC
Hip Extensors in the back squat:
60 degrees of knee flexion - 27.7% MVIC
90 degrees of knee flexion - 43.7% MVIC
120 degrees of knee flexion - 35% MVIC
According to the data, between 60° and 90° of knee flexion, squatting to 90° recruits a higher percentage of motor units, as long as it can be done safely. When front squatting to 90°, the knee extensors are recruited 20.9% more, and the hip extensors are recruited 14.2% more than when front squatting to 60°. The same goes for back squats: if you squat to 90°, your quads are recruited 23.5% more, and your hamstrings and glutes are recruited 16% more than when squatting to 60°.
Considerations for "ass to grass" squatting
So, what about squatting ass to grass, or 120° of knee flexion? Is the hype real? Squatting to this depth only recruits the highest percentage of motor units for the knee extensors in the back squat, and it is only by 3.4%. Outside of that, 90° recruits most. Now, I know what you may be thinking. What is with all these people promoting full depth squatting then? Well, there's a few more considerations to take into account:
The full contraction: These measurements are taken as a freeze frame at each depth. They do not consider the eccentric or concentric components necessary to get to and from that point. This means that in order to get to 120°, you have to pass through 90° on the way down, and on the way up. In other words, just because the % MVIC is a little less at 120° than 90°, this doesn't mean you're losing those contractions at 90°.
Time under tension: 120° requires more distance covered than 90°. This means if you squat at the same velocity, you will spend more time under tension performing an "ass to grass" squat, which can be beneficial for hypertrophy, ligament/tendon strength, and mobility.
Mobility: If your mobility allows you to passively get into certain positions, training through those ranges of motion is a wise consideration as it can enhance your performance in competition by preparing your body to stabilize and produce force in a variety of positions. By loading different ranges, you can ensure that your body is neurologically prepared for any potential competition scenarios.
Olympic lifting: If you are someone training to get better at the olympic lifts (clean and jerks and/or snatches), it is imperative you devote at least some training to squatting full depth. The lower you can comfortably receive a barbell, the lower you need to pull it, and ultimately the more weight you'll be able to lift.
It’s important to keep in mind that what 90° or 120° of knee flexion looks like for one person may not be the same for another. This is due to differences in anatomy and mobility at various joints, such as the ankles. This is why it is important to pay attention to the actual angles created at the hip and knee more so than if someone looks like they're getting "to parallel" or "below parallel."
Important Takeaways
With all this said, the most important take away is that there are benefits to squatting deeper, but only to the capabilities of your body. This means that if you can only get to 75° degrees without your back rounding and heels coming off the ground, that's as far as you should go until we can improve your form through technical work, mobility work, or find a way to promote more depth safely, such as adding a heel lift. If you have the ability to squat to below 90°, it would be wise to go to at least 90°, and understand that there are benefits of going deeper than that, if they apply to you, and when you should implement that training stimulus.
Conclusion
In conclusion, while there is no one-size-fits-all answer to the question of the correct squat depth, the data clearly shows that squatting to 90° recruits a higher percentage of motor units. And as we know, there are benefits to squatting below that. As long as it can be done safely, it comes down to deciding what you're training for and if the benefits of squatting "ass to grass" apply to you, or if going to 90° will fulfill your training needs.
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