ISSA, International Sports Sciences Association, Certified Personal Trainer, ISSAonline, The Squat: Muscles Worked, Form, Variations, and More

Corrective Exercise

The Squat: Muscles Worked, Form, Variations, and More

Reading Time: 6 minutes 19 seconds


Date: 2021-12-09T00:00:00-05:00

When compared to other strength training exercises, squats aren’t overly complicated. They can also be modified to make them easier or more difficult. This makes squatting a good option for clients of all fitness levels.

Yet, as a trainer, it’s your responsibility to know which clients would benefit most from adding this exercise into their workout. This includes knowing when to suggest the squat as a bodyweight exercise and when to use additional weight. Or when a squat variation might be best.

We’ll go over all of this. But first, let’s start with identifying the muscle groups that are worked when squatting.

Muscles Worked During Squats

Squats activate a variety of lower body muscles. This includes the:

  • Glutes (gluteus maximus, medius, and minimus)

  • Hip flexors (iliacus, psoas major, and sartorius)

  • Quadriceps (vastus lateralis, vastus medialis, and rectus femoris)

  • Hamstring muscles (semitendinosus, semimembranosus, and biceps femoris)

  • Calves (gastrocnemius, soleus, and plantaris)

The form used when squatting helps determine the level to which some muscles are activated. For example, one study involved subjects doing squats with their knee displaced either anteriorly or medially. When the knee was displaced medially, there was less activation of the quads. When the knee was displaced anteriorly, there was greater activation in the vastus lateralis and rectus femoris during the initial ascent. Activation of the biceps femoris and gastrocnemius was greater in both misalignments when compared to a control.

Benefits of the Squat Exercise

What are some reasons to add squats to a client’s weightlifting workout? One is that they can increase lower body strength. This is helpful for performing everyday movements such as walking, running, or hiking. Strong legs also make it easier to push a mower or pull kids in a sled.

Certain athletes benefit from increased muscle strength in the lower body. This includes those that play soccer or basketball. Track and field runners, gymnasts, and swimmers also benefit from strong legs, glutes, and hips.

Research indicates that “the squat is among the top three prescribed exercises for sports training, rehabilitation and prehabilitation.” When used in sports training, it can improve an athlete’s performance. This includes improving sprint speed and vertical jump height. As a means of rehab or prehab, squats can be used to improve balance or reduce muscle loss in older adults.

Bodyweight Squat vs Weighted Squats vs Resistance Band Squats

The amount of weight used when squatting changes its level of intensity. Using one’s bodyweight makes this exercise less intense than using a barbell, for instance. Using dumbbells or a kettlebell fall in between the two.

The bodyweight version can also be beneficial for clients who want to work out at home or while traveling. Because it requires no equipment, they can do this exercise anywhere. Conversely, they’re more likely to do a barbell squat while in the gym.

Using bands offers another resistance training option suitable for almost any exercise setting. Start with a band that offers lighter weight resistance. Once that weight feels easy, move up to the next resistance band. Or, if using an actual weight, increase that weight by five or ten pounds.

Proper Squat Form

As previously mentioned, proper form is necessary to activate the desired muscles. Using good form can also prevent injuries. What does proper form look like when doing squats?

Have the client stand with their feet shoulder width apart. Their back is straight, shoulder blades back and down, and abs pulled in. When squatting, they should push their hips back and lower their body toward the floor. The goal is to get the thighs parallel to the ground.

If they struggle with form, ask the client to imagine that they’re getting ready to sit on an imaginary chair. This should help them get into the proper position. Once they’ve completed the squat, the exercise concludes by having them stand back up.

Common Squat Mistakes

One thing to watch for as a trainer is that the client’s knee does not extend beyond their toe. If it does, this can increase the stress on the knee joints.

Another common squat mistake is an excessive forward lean. When doing squats, the upper body should only lean forward slightly. If the client is bending too much at the hips, ask them to keep their torso more upright. This can help protect the back and hips from injury.

Also pay attention to the client’s squat depth. If their goal is to build a better physique, a greater squat depth can help. But if their goal is to jump higher, a more shallow squat is best.

The client’s fitness level also impacts how far they can squat. When first starting out, they might find it difficult to get the thighs parallel to the floor. As they become more fit, they will likely find it easier to squat to lower levels. In this way, the squat can be used to measure their progress.

ISSA, International Sports Sciences Association, Certified Personal Trainer, ISSAonline, The Squat: Muscles Worked, Form, Variations, and More, Overhead Squat

Squat Variations

The great thing about squats is the many different variations from which to choose. Some of these variations make the exercise easier while others make it harder. Using different forms of this movement also keeps exercise fun. You don’t get bored doing the same basic squat over and over again.

Here are a few variations to consider when mixing up your client’s lower body routine:

  • Partial squats. If a client struggles with squats, only have them lower down part of the way. Start by having them squat a few inches. As they develop more strength, begin to increase the squat depth.

  • Assisted squats. This variation is good for clients with balance issues. It involves holding a chair or wall while squatting down.

  • Air squat. The air squat is just another name for a bodyweight squat. As such, no weights are used as you work only against your own body’s weight for resistance.

  • Sumo squat. In a sumo squat, the feet are wider than hip width apart. Also, the toes point out to the side versus pointing forward. This wider stance helps better target the inner thighs.

  • Split squat. A split squat is a combination between a lunge and a squat. The legs are staggered so one foot is in front of the other. Next, the body is lowered toward the ground. The back remains upright and core muscles engaged.

  • Jump squat. You can make the squat more explosive by adding a jump at the end. After dropping into a squat, the client pushes off their heels to lift their entire body into the air. The arms start out extended in the air, then swinging them down to the sides during the jump. This helps propel the body upward.

  • Box squat. If clients use a barbell, they can add variety to their lower body routine by doing box squats. This move involves holding the barbell on the back of their shoulders. Next, they lower down until their butt barely touches the box before standing back up.

  • Overhead squat. Another option when using a barbell is an overhead squat. This requires lifting the barbell overhead and holding it there while doing a squat. Proper form is important for protecting the lower back.

  • Goblet squat. You use a kettlebell or dumbbell for this squat. To do it, the weight is held in the front and center of the body. The arms are fully extended, holding the weight as the body lowers toward the floor.

  • Squat thrust. This variation involves lowering into a squat, then kicking the feet back and lowering your body into a plank position. It’s like doing a burpee with no jump when you stand back up.

  • Pistol squat. More advanced clients might prefer a pistol squat. This one-legged squat involves doing a squat with the other leg extended outward. Holding the arms out front can help keep balance while in this unstable position.

Who Should Not Do Squats

Some clients may want to avoid doing squats. This includes those with knee pain such as patellofemoral syndrome. Talking to their doctor can help determine if squats or a squat variation are safe to perform given their physical condition. Or the doctor may suggest using knee wraps to provide additional support.

If the client experiences knee pain only while doing the squats, an improper form may be to blame. Watch their knees as they lower their body. Look for knees that cave inward (knee valgus) or that bow outward (knee varus). Work with them to keep the knees straight during the entire movement.

Clients with back pain might also want to skip squats and do another lower body exercise instead. This is especially important if they typically use weight while performing the squat.

Earning your certification as a Corrective Exercise Specialist can teach you the skills needed to help clients with movement limitations and pain. This includes learning how to analyze their movement and restore their structural alignment, enabling them to meet their fitness goals in a way that suits them best.


Slater, Lindsay V., and Joseph M. Hart. 2017. "Muscle Activation Patterns During Different Squat Techniques". Journal Of Strength And Conditioning Research 31 (3): 667-676. doi:10.1519/jsc.0000000000001323.

Vecchio, Luke Del. 2018. "The Health And Performance Benefits Of The Squat, Deadlift, And Bench Press". MOJ Yoga & Physical Therapy 3 (2). doi:10.15406/mojypt.2018.03.00042.

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