What Muscles Do Squats Work? Maximize Your Benefits from the King of Leg Exercises

• Initial Phase: Before beginning the descent, brace your core by taking a deep breath through your belly, increasing pressure within your abdominal cavity. This technique enhances lower back rigidity and overall posture. Consider using a lifting belt for added support. To keep the brace in your core, breathe through your nose, and do not allow your shoulders to rise during your initial breath. 

• Descending Phase: As you lower into the squat, ensure your hips move downward and slightly back to distribute the weight evenly across your mid-foot. The goal is to maintain proper alignment between your knee and hip joints. Aim to reach a comfortable depth, with your thighs near parallel to the ground or slightly lower.

• Ascending Phase: During the ascent, pay attention to potential “sticking points” as the load gets heavier. When your strength gets challenged, technique becomes crucial. The better your technique is from start to finish, the more likely you can battle through that sticking point to complete the lift. Return upright to a full lockout.

By following each of these steps and maintaining proper form throughout the movement, you’ll maximize head-to-toe muscle engagement and reduce the chances of common mistakes, ensuring a successful and effective squat.

Muscle Recruitment During Squats

Time to dig deep into the anatomy of the barbell back squat, exploring the primary muscles and secondary muscles required to perform the movement.

The barbell back squat recruits a combination of primary and secondary muscles, with the quadriceps and glutes taking the lead in knee and hip extension, respectively. Proper engagement of these muscle groups, and the support of secondary muscles, is crucial for executing a safe and effective squat.

Primary Muscles

A primary muscle is the main targeted muscle used during an intended movement. The muscles tend to be the larger muscles of the anatomy, especially during a compound movement which involves moving at multiple joints — in the squat, you’re moving at the hips, knees, and ankles. The primary muscles of the squat are the quadriceps and the glute maximus.

Quadriceps 

• The quadriceps are a group of four muscles located at the front of the upper leg. 
• The primary function of the quadriceps is knee extension, which is crucial during the ascending phase of the squat. They play a pivotal role in straightening the knee joint as you lift the weight.
• The quadriceps are heavily engaged when an athlete relies on their knee joint to move the weight. The knee joint might be prioritized during a high-bar squat, a squat to full (below parallel) depth, or when the athlete’s knees begin to break far in front of their toes. 

Glutes 

• The gluteus maximus, the largest of the gluteal muscles, forms the bulk of the hip joint. 
• The glutes are responsible for hip extension, which is crucial for rising from a squat position. They provide the power needed to straighten the hips.
• The gluteus maximus is heavily engaged when an athlete starts to rely more on their hip joint to drive the weight up. The hip joint might be prioritized when an athlete performs a low-bar squat, box squat, or when the athlete has “vertical shins,” which means they are putting more weight on their heels than their toes. 

Secondary Muscles

A secondary muscle tends to be a relatively smaller muscle group that aids the primary muscle(s) with executing an exercise. The secondary muscles that provide support and stabilization during the squat are the hamstrings, calves, lower back, and core muscles.

Hamstrings

• The hamstrings are located at the back of your upper leg, running from your hips to you knees.
• While primarily responsible for knee flexion (like leg curls), the hamstrings assist in hip extension (straightening your upper leg in line with your torso). Your hamstrings help control the descending phase of the squat, acting as stabilizers.

Calves

• The calves are comprised of the gastrocnemius and soleus muscles, and are located behind your lower leg.
• The primary function of the calf muscles is the extension of the ankle joint — “pointing” your foot down. While not directly involved in the squat, they help stabilize the ankle joint, especially when pushing through the mid-foot. If you want to have a great squat, you want to keep your feet flat during each rep, meaning you need great ankle mobility, which relies on flexible calf muscles. 

Erector Spinae (Lower Back)

• The erector spinae muscles run along your spine’s length, supporting and stabilizing your lower back, especially. 
• The erector spinae muscles are responsible for spinal extension, helping to maintain an upright torso position during the squat.

Core

• Your core includes muscles such as the rectus abdominis, obliques, and transverse abdominis.
• Core muscles provide stability to the torso, helping maintain proper posture and preventing excessive spinal flexion or extension. They work in conjunction with the erectors, as well.

How to Emphasize Key Muscles

As mentioned earlier, the primary muscles used to squat are the quadriceps and the glutes. However, to emphasize one muscle group over the other depends on adjusting your setup and movement, including foot placement, stance, depth, and barbell placement. (4)

Maximizing Quadriceps Recruitment

For those seeking to grow and strengthen their quadriceps, start by positioning your feet closer together, either at shoulder-width or slightly narrower. This narrower stance magnifies the involvement of your quadriceps during the squat, intensifying their engagement.

To further emphasize quadriceps recruitment, favor a high-bar placement with the barbell on your upper back. Placing the bar higher on your back shifts your center of gravity forward, ensuring that your quadriceps take the brunt of the load.

This strategic bar placement is a key element in effectively targeting and strengthening the quadriceps, especially for those in a hypertrophic (muscle-building) phase of training. 

Another trick toward quad-dominance is going below a parallel depth. This increased depth tends to cause the shins to lean forward, putting the ankle within a great range of motion (also known as “dorsiflexion”) which will put more strain on the knee joint. This causes the quadriceps to be more activated.

Maximizing Glute Recruitment

If your objective centers on maximizing glute engagement, widen your stance beyond a shoulder-width position and point your toes out. This can influence your shins to stay upright, redirecting the focus to your glutes and intensifying their involvement.

You should also use a low-bar position to shift the weight distribution at your hip joints. This helps you get a better hip hinge, which accentuates glute recruitment. Placing the bar lower on your back ensures that the glutes play a more dominant role in the squat.

For those who struggle with feeling glute recruitment, try including a “pause” in the bottom position, or even use a box squat variation, as the box enforces the cue to push your hips backward instead of down. That’s a key point— if your hips move further back, your glutes can be more engaged.

Squatting straight down pushes your upper thighs forward as you descend, causing your knees to be more recruited, which would cause a more quadriceps-dominant action.

Squat Variations

There are a few other squat variations that can be used to further emphasize recruitment of either your quadriceps or glutes. By making changes to the bar position or, in some cases, avoiding the standard barbell completely, you can force your body to recruit different muscles while performing the same fundamental squatting movement.

Front Squat

In this variation, the barbell is positioned on the front of your shoulders rather than across your upper back. To achieve this unique position, you can either cross your arms over each other to hold the barbell or use an Olympic weightlifting-style “rack” position that puts your arms parallel to each other with your arms bent and the bar near your fingertips.

The defining feature of the front squat is its demand for a more upright torso posture. This is what would make the movement more quadriceps-dominant than glute-dominant, similar to a high-bar squat. 

The front squat promotes improved posture and spinal alignment. It strengthens your upper back while reducing the risk of forward-leaning tendencies often associated with the classic barbell back squat.

SSB Squat

The SSB (safety squat bar) is a specialized barbell that has pads and forward-pointing handles that hold the weight on top of your shoulders and upper back. The weight distribution creates a forward-leaning upper body angle compared to a standard barbell , which significantly impacts the mechanics of the squat. This makes it a more quadriceps-dominant variation.

The SSB squat is an ideal choice for individuals who may have mobility limitations in certain areas like the shoulders. Additionally, the SSB squat places a substantial focus, not only on the quadriceps, but also the upper back and the posterior chain. It delivers a great challenge to not just quadriceps strength, but postural strength as well. 

In terms of muscle engagement, the primary target during the SSB squat is your quadriceps. However, the angled handles also bring your upper back and posterior chain into play. This shift in muscle emphasis sets it apart from the classic barbell back squat, which primarily targets the quadriceps but doesn’t engage the upper back and posterior chain to the same extent.

Belt Squat

The belt squat is unlike the front squat or SSB squat. Instead of placing a barbell on your upper body, you wear a belt around your waist attached either to a specially designed platform or to a barbell on the ground set in a landmine unit. The belt distributes weight across your hips, which makes it a glute-dominant variation of the barbell squat.

The belt squat offers an effective means of challenging the lower body without placing weight on your torso and spine, making it particularly suitable for individuals dealing with back issues.

Additionally, the belt squat targets your legs with little to no upper body involvement. This would be a great exercise for those with specific limitations, including poor shoulder mobility, spinal compression issues, or an inability to hold a barbell with one or both arms.

Time to Squat

The barbell back squat is a top exercise that engages multiple muscle groups and delivers massive benefits, from increasing strength and power to building more muscular legs. Overall muscle recruitment during squats is a crucial variable that can be manipulated by your stance, movement, and bar position. No matter how you do it, the squat is an iconic lift that can improve anyone’s success in building size, strength, and athleticism. 

References

1. Myer, G. D., Kushner, A. M., Brent, J. L., Schoenfeld, B. J., Hugentobler, J., Lloyd, R. S., Vermeil, A., Chu, D. A., Harbin, J., & McGill, S. M. (2014). The back squat: A proposed assessment of functional deficits and technical factors that limit performance. Strength and conditioning journal, 36(6), 4–27. https://doi.org/10.1519/SSC.0000000000000103
2. Wilk, M., Petr, M., Krzysztofik, M., Zajac, A., & Stastny, P. (2018). Endocrine response to high intensity barbell squats performed with constant movement tempo and variable training volume. Neuro endocrinology letters, 39(4), 342–348.
3. Ribeiro, Alex & Santos, Erick & Nunes, João Pedro & Amarante do Nascimento, Matheus & Graça, Ágatha & Bezerra, Ewertton & Mayhew, Jerry. (2022). A Brief Review on the Effects of the Squat Exercise on Lower-Limb Muscle Hypertrophy. Strength and Conditioning Journal. Publish Ahead of Print. 10.1519/SSC.0000000000000709.
4. Larsen, S., Kristiansen, E., Helms, E., & van den Tillaar, R. (2021). Effects of Stance Width and Barbell Placement on Kinematics, Kinetics, and Myoelectric Activity in Back Squats. Frontiers in sports and active living, 3, 719013. https://doi.org/10.3389/fspor.2021.719013

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