How Deep Should You Squat? Full, Parallel or 90 Degrees?

If you want bigger quads, how deep should you squat? Is squatting to parallel good enough? Or is arse-to-ankles, which basically means as low as you can get, the only way to go?

Who’s right? We’ll find out in a moment.

First, I want to define what a parallel squat is, take a closer look at how it’s done, before digging into the research comparing parallel with full-depth squats.

What is a Parallel Squat?

Squatting to parallel involves squatting down to the point where your femur, the large bone in your thigh, ends up roughly parallel to the floor.

Viewed from the side, your hip crease (called the inguinal crease) will drop slightly below the level of your knee joint.

The middle squat below (image B), which comes from this study, gives you a better idea what a parallel squat looks like.

That’s a parallel squat. Anything above that doesn’t really count.

It’s actually lower than you think, and involves flexing the knees to around 125 degrees. Very few people in the gym get that low, and most will stop a few inches short of hitting parallel.

How to Do a Parallel Squat

In the video below, Canadian bodybuilding champion Jeff Nippard shows you how to do the back squat.

Here’s how it’s done:

• Rest the bar across your traps and keep tight hold of the bar.
• Step back from the rack and assume a (roughly) shoulder width stance.
• Your toes should point slightly outwards rather than straight ahead.
• Maintain this stance throughout the exercise.
• Brace your abs before starting the descent.
• Your knees and toes should point in the same direction while you descend.
• Maintain the natural arch in your lower back throughout the exercise.
• Bend at the knees until your thighs are parallel to the floor.
• Don’t let your heels lift off the floor. If you’re having trouble keeping your heels down, you can always try wearing some weightlifting shoes. These shoes keep your heels in an elevated position, and provide a lot more stability than regular running shoes.
• Return to the starting position.

What Muscles Do Squats Work?

The barbell squat is a highly effective way to train the quadriceps, which is made up of four different muscles:

• Vastus Medialis
• Vastus Lateralis
• Vastus Intermedius
• Rectus Femoris

Of the four, the squat works mainly vastus medialis, vastus lateralis and vastus intermedius. Rectus femoris is recruited, but not to the same extent as the other three muscles that make up the quads.

The gluteus maximus, erector spinae and adductors are also involved, but to a lesser degree.

Is it Bad to Squat Past Parallel?

Done properly, squatting past parallel is safe and effective. However, you should squat no deeper than the point where you lose the arch in your lower back. This may be slightly above or slightly past the parallel position.

That is, some people will find that a parallel squat is as deep as they can go. Others will need to stop slightly above parallel. Only a very small number of people can do ass-to-grass squats without losing the natural curvature in their spine.

In fact, one of the classic signs that your squat technique needs some work is so-called butt wink, where your pelvis tucks under and the lumbar spine rounds excessively.

If you blindly follow the advice to squat arse-to-ankles (or even to parallel) while ignoring what’s happening to your lower back, the potential for some kind of disc injury is greatly increased.

Neutral spine isn’t a single position that your back never deviates from. Think of it more like a neutral zone, or a range that your spine can move within while still posing a low risk of tissue damage.

In this video, Professor Stuart McGill, an expert in spine function and injury prevention at the University of Waterloo in Canada, explains exactly why losing neutral spine position during the squat, especially when you’re lifting heavy loads, isn’t doing your lumbar spine any favors.

Your ability to maintain a neutral spine during the squat depends on a number of factors. These include:

• The strength of the muscles around the hip
• The flexibility/mobility of the hip and knee joint
• The relative lengths of your torso and thighs.

If you have relatively long thighs, for example, you’ll have to shift your weight back by leaning forward as you squat.

Combine this with a lack of flexibility/mobility in the hip area, or lack of strength in the spinal erectors, and you’ll find it very difficult to get below parallel without losing the arch in your lower back.

Bret Contreras explains more about how differences in anatomy from person to person affect squat depth in the video below.

“If squatting makes your joints cranky, consider setting your depth to a point that allows you to load up and still feel great afterwards,” explains Geoff Girvitz of Bang Fitness.

“Sometimes the difference of a single inch of depth can be huge in terms of impact to hip or low-back health.”

Is Squatting Past Parallel Bad for Your Knees?

Many health professionals recommend squatting no lower than parallel or higher. This is based on the idea that going too deep can generate dangerously high forces at the knee joint, increasing the risk of a knee injury.

It’s true that squatting past parallel tends to increase forces at the knee, even accounting for the fact that you’re lifting lighter loads [5].

However, whether this is going to increase your risk of a knee injury depends every much on the individual in question.

There are many potential sources of painful knees, and something that has an adverse effect on knee health in one context isn’t necessarily going to have the same effect in another.

The fact that an exercise puts “stress” on a particular joint isn’t necessarily a bad thing.

Tendons, ligaments and even bone can adapt to various stresses in such a way that they’re better able to cope with that stress in future.

That’s how your muscles grow. You expose them to a level of stress they’re not accustomed to, which in turn stimulates a positive adaptation, namely muscle growth.

The problem with stress is when it’s applied in such a way that whatever tissue being stressed can’t adapt.

But that doesn’t necessarily make squatting past parallel a bad idea, just a bad idea for some people in certain situations.

Are Parallel Squats Effective?

If you can’t squat arse-to-ankles, don’t worry. Squatting to parallel is still an effective way to make your quads grow.

In fact, research that compares the full-depth and parallel squat shows very little difference in muscle activity between the two.

Dr Rafael Escamilla, a Professor in the Department of Physical Therapy at California State University, reviewed a total 70 studies on the subject of knee biomechanics during the squat [1].

He found that squatting roughly to parallel is enough to achieve very high levels of muscular activity in the quadriceps, which is going to make your legs bigger and stronger.

Researchers from Edge Hill University looked at muscle activity during full-depth, parallel and shallow squats (quarter squat), using relative 5-rep-max loads [3].

In other words, subjects lifted the most weight during the shallow squat, and the least during the full squat.

Muscle activity in the hips and thighs was greater during parallel and deep squats compared to the partial squat. However, the differences between the full-depth and parallel squat were, to quote the study authors, “negligible.”

There is research to show that muscle activation of the glutes is maximized during deep squats [2]. However, the main weakness with this study is the fact that subjects used the same weight for both the full and parallel movement.

Why is that a problem?

Most people can lift heavier loads when they only go to parallel. And muscle recruitment is highly dependent on the amount of weight you’re lifting. Squatting with heavy weights will call into action more muscle fibers than squatting with a lighter weight.

Follow-up studies that take into account the fact that you can lift heavier weights in a parallel versus a full squat show that the glutes are just as active with parallel as they are with full-depth squats [3].

How Squatting to Parallel Affects Muscle Growth

While it’s always interesting to look at how this or that exercise affects different muscles, short-term differences in muscle activity don’t always translate to long-term differences in muscle growth.

That is, you can’t always rely on EMG to tell you which exercise will lead to more muscle being gained.

For that, we need research to look directly at long-term changes in muscle mass, rather than short-term differences in muscle activation.

One such study, published in the European Journal of Applied Physiology by a team of Japanese researchers, looked at the rate of growth in various muscles after 10 weeks of squatting [4].

• Group one squatted to 90 degrees of knee flexion.
• Group two went all the way down, defined as 140 degrees of knee flexion.

The image below, which comes from this study, give you an idea what those knee flexion angles look like:

A = Above parallel (roughly 95 degrees knee flexion)
B = Parallel (roughly 125 degrees of knee flexion)
C = Below parallel (roughly 140 degrees of knee flexion)

So, what happened? Which group gained the most muscle?

MRI scans taken at the start and end of the study show no significant difference in the rate of quad growth between the two groups.

That is, whether the men squatted to 90 degrees of knee flexion, or arse-to-ankles, the increase in quad size was virtually identical.

What about the hamstrings?

Neither the full squat nor the 90 degree squat led to a change in hamstring size over the course of the 10-week study.

That’s because hamstring muscle activation during the squat is relatively small. If you want to train your hamstrings, your workouts will need to include exercises like the Romanian deadlift or leg curl.

The squat isn’t an effective way to train the calves either. They are involved in the exercise, but not to a degree that’s sufficient to stimulate much in the way of muscle growth.

If you want bigger calves, your lower body workouts will need to include exercises like the standing or seated calf raise.

Although full squats didn’t make the quads grow any faster than squatting to 90 degrees, they did lead to a faster rate of muscle growth in both gluteus maximus and the adductors.

Gluteus maximus

• Full + 6.7%
• 90 degrees + 2.2%

Adductors

• Full + 6.2%
• 90 degrees + 2.7%

Of course, this doesn’t mean that if you don’t do full squats, your glutes are doomed to stay in the muscle-building slow lane.

Squats aren’t the only show in town. There are plenty of other lower-body exercises you can do, such as the same leg chain lunge, step ups or the Bulgarian split squat.

These exercises allow you to work through a larger range of motion while your torso remains upright. As a result, they’re harder on your glutes while simultaneously being a lot easier on your spine.

Same Leg Chain Lunges

Bulgarian Split Squat

Step Ups

Some people will tell you that if it’s not arse-to-ankles, squatting won’t make much of a contribution to gains in lower body strength and size because it wasn’t done through a full range of motion.

Many of these same people will then go on to recommend the deadlift as one of the best overall mass building exercises for the entire body. That’s despite the fact there is not one muscle group that is taken through a full range of motion during the deadlift.

Bottom line?

Unless you’re an athlete trying to improve your performance in a sport where you need to be strong in a deep squat position, don’t worry if you can’t get below parallel.

In the sport of powerlifting, for example, the typical requirement is that you must squat below parallel in order for your lift to count.

The International Powerlifting Federation, for example, requires the lifter to squat down until “the top surface of the legs at the hip joint is lower than the top of the knees.”

If you’re a competitive powerlifter, you’ll need to make sure you hit that depth in your training sessions. But if you’re not a powerlifter, and all you care about is making your legs bigger, there’s no special reason to go that low.

SEE ALSO: Squat Alternatives: Bad Knees, Back or Hips?

Frequently Asked Questions

Is squatting to 90 degrees the same as parallel?

Squatting to 90 degrees isn’t the same as parallel. Squatting to parallel involves squatting down to the point where your femur ends up roughly parallel to the floor, which is roughly 125 degrees of knee flexion. Squatting to 90 degrees is actually slightly above parallel.

Is it better to squat heavy or light?

If you want to get strong, squatting with heavy weights and low reps is the way to go. For building muscle, you can train with heavy weights and low reps, or light weights and higher reps, and you’ll see a similar level of muscle growth.

How many days a week should I do squats?

Some advanced strength athletes have made impressive strength gains by squatting 4-6 days a week. But for most people, most of the time, squatting 1-3 days a week will do the job.

Final Thoughts

Contrary to what the exercise police might say, there is no one size fits all recommendation when it comes to squat depth, and the ideal range of motion will vary from person to person.

You should squat to a depth that allows you to maintain good form. By that, I mean you should go no deeper than the point where you lose the tight arch in your lower back. This may be slightly below or slightly above parallel.

It’s far better to be an inch or two on the high side than go too deep and end up with a crippling back injury because of it. Even squatting above parallel is still deep enough to make your quads bigger and stronger.

However, it is important to reach a consistent depth, so you have a point of reference to measure your progress.

Don’t delude yourself into thinking that you’re increasing your strength when all you’re really doing is decreasing your depth in order to lift heavier weights. Have a firm standard for what constitutes a squat, and stick to it.