Squats have developed a reputation as a booty-building exercise — but the truth is that they strengthen almost every muscle in your lower body. When you do squats, the muscles worked include your quads, glutes, hamstrings, calves and even your core muscles.
When you do squats, you're working your glutes and quads, in addition to your hip adductors, hamstrings, calves and core muscles.
Muscles Worked in a Squat
Your quadriceps and glutes are the most powerful of the muscle "engines" that drive you through the squat motion. As you're coming up out of the squat position, your quadriceps fire to straighten your legs at the knee, while your glutes straighten your body at the hips. The end result of this simultaneous action? You stand up.
The reverse happens as you sink back down into the squat: Your quadriceps and glutes both lengthen under load as you flex at the hip and the knee, a movement known as an eccentric contraction. This lengthening under load is what controls your descent and keeps you from simply plopping onto the floor at the mercy of gravity.
However, as you might expect, there's more going on during this exercise than the brute force of your quads and glutes. When you do squats, the muscles worked also include:
Your soleus muscle, the smaller of your two primary calf muscles, is responsible for plantar-flexing your foot (or to put it another way, pointing your toes) when your knee is bent. And although your heels never come off the ground during a squat, plantar-flexion is still the motion that helps return your shin to a vertical position from the slight forward lean it assumes when you're in the "down" position of the squat.
Because your knee is bent while plantar-flexion is happening, your gastrocnemius — the bigger, meatier muscle that sits on the outside of your calf — isn't providing much power to the movement, but it does help stabilize your leg.
Hamstrings and Adductor Magnus
When you do squats, the muscles worked also include your hamstrings. As noted in a very useful squat analysis from ExRX.net, the hamstrings counter the direct forces of your quadriceps to help stabilize your knee, reducing shearing forces and strain across the joint.
Another notable muscle, the adductor magnus, keeps your hamstrings company on the posterior (rear) part of your thigh. This muscle also kicks in to help your glutes power the movement, extending your leg at the hip.
Because your hips hinge backward, a certain amount of forward torso lean is necessary to make squats happen — which means your core muscles all play an important part in maintaining proper squat form and preventing injury.
The further forward you lean, the more your erector spinae muscles are involved in holding your back straight, while your rectus abdominis (the so-called "six-pack muscle") and obliques counter the pull of the erector spinae to keep you stable.
Proper Squat Form
Of course, you're only going to get that sort of muscle engagement if you use proper form. Squats are an endlessly versatile exercise that you can do with only your body weight for resistance, or using dumbbells, kettlebells or a barbell for extra weight.
The barbell squat (or to some, back squat) is a great example for teaching the key points of proper form. In addition to that barbell, you're going to need a squat rack — a sturdy metal frame with equally sturdy pins that you can rack, or rest, the barbell on. Here's how you get into proper position to do a squat:
- Rack the barbell at just below shoulder height and, if necessary, add weight plates. Note: If you're just starting out, it's best to practice this exercise with no weight at all, working up to using the barbell (which usually weighs 45 pounds on its own) and, then and only then, adding weight to the bar.
- Duck under the barbell and situate yourself so that it rests on the meaty portion of your upper back, just behind your neck. The barbell should not rest directly on your neck. Some people will need the aid of a "neck roll" (padding that wraps around the bar) to make this position comfortable.
- Squeeze your abs (think "chest up, shoulder blades together and down") to stabilize your core as you stand up, lifting the bar off the rack. Take a step back so that the bar will clear all portions of the rack when you squat.
Once you've accomplished that, the actual process of doing your squats is quite straightforward — although proper attention to form is still critically important for avoiding injury.
- Place your feet slightly wider than shoulder-width apart.
- Squat down as if you were sitting in a chair; the motion starts in your hips as they sink back and your torso tilts forward, just a bit, to keep the barbell centered over your feet. Squeeze your core muscles to keep your back flat and chest up as your torso hinges forward and your knees bend, sending your hips down and back.
- Stop when your hips break the plane of your knees.
- Drive through your feet and legs as you stand back up.
If you're just starting out, one or two sets of eight to 12 repetitions is a good goal. Once you're done with your set, step forward and carefully lower the bar back onto the racking pins. Make sure it's safely racked on both sides before you step out from under it.
Make sure you put weight collars on your barbell when you add plates. These spring-loaded clips stop the weight plates from sliding off if you tip the bar to either side.
Watch for These Mistakes
Squat injuries are often caused by mistakes in form — so at the risk of repetition, it's worth recapping key issues to avoid. Some common mistakes to avoid, and their fixes, include:
1. Letting Your Knees Cave Inward
Reduce the amount of weight you're lifting and use a mirror or a lifting buddy for feedback as you focus on keeping your knees "up" instead of letting them sag in. It might help to pay close attention to your feet: Sometimes reminding yourself to push through your entire foot (instead of just the inside edge) will help correct this.
Here's another useful cue that might help: Your toes should point straight forward or slightly out and, from your perspective as you look down the length of your body, your knees should always point in the same direction as your toes.
2. Tilting the Bar
The barbell may tip to the side if you're lifting too fast, lifting too much weight or if one side of your body is weaker than the other. The solutions are easy: Slow down, reduce the weight, and/or use a mirror or a buddy for feedback as you focus on driving or sinking equally through both legs in a smooth, controlled motion. If an imbalance persists, a medical or fitness professional might prescribe unilateral (one-sided) exercises to strengthen the weaker leg.
3. Not Hinging at the Hips
Some people try to do squats without leaning forward from the hips at all — but this places a lot of pressure on your knees. Your hips actually start the motion, moving down and back, which in turn requires your knees to bend and your torso to tilt forward slightly.
4. Lifting With Your Back
Have you ever heard the directive "Lift with your legs, not your back"? That certainly applies to squats — so, when you begin to stand back up, think of pressing through all of both feet and driving with your legs to initiate the motion. If you try to start the motion in your back instead, you'll get hurt.
Variations on the Squat
You'll find almost endless variations on the squat, usually based on where you place your feet, what sort of weight you use or where you hold the weight. A few key variations to be aware of include:
Front squats: In this exercise, you hold the barbell across the fronts of your shoulders. As confirmed by EMG (electromyography) analysis in a small study of 12 participants, published in the Journal of Sports Sciences, the front squat emphasizes quadriceps activity and decreases trunk lean. That makes it potentially a good choice for those with back concerns, but a poor choice for those with knee issues.
The goblet squat, in which you hold a single kettlebell in front of you by the "horns" or handle, is a variation on the front squat.
Wide squats: You can do squats with an increasingly wider stance until you hit the wide, toes-out stance of the plié squat — as long as you follow the cardinal rules of proper form: Your knees must always point in the same direction as your toes, and don't let your knees cave in toward your midline.
As noted in the ExRX.net squat analysis, a wide stance emphasizes the involvement of your hip adductors, or inner thigh muscles. Glute activity increases when you do wide squats with a heavy load, and it's worth noting that hip torque increases as well — so if you struggle with hip pain, this probably isn't the squat variation for you.
Dumbbell squats: Doing your squats with dumbbells means giving up some of the overall stability of the barbell — but in return, you get more flexibility in the way you hold the weights. Two of the most common variations are letting your arms rest by your sides (so the dumbbells "ride along" on the outsides of your body throughout the squat) or holding the dumbbells racked at shoulder level. The latter more or less mimics the positioning of a barbell, but gives you greater flexibility in the angle at which you hold your hands.
Another dumbbell variation is holding a single weight by one end and letting it dangle between your legs as you squat. This variation sometimes makes it easier for beginners to achieve proper form, and it allows you to do wide squats. But, depending on the size of the weight you're using, the lower end of the weight may contact the ground and thus limit your range of motion.
What About Smith Machines?
Whether or not Smith machines are an acceptable tool for doing squats is a subject of some controversy. The Smith machine has a couple of very useful safety features, such as height-adjustable stoppers that will support the bar if you get "stuck" at the bottom of the squat, and a self-spotting hook on the bar that you can rotate to lock the bar in place. Like the adjustable stoppers, this gives you a graceful (and potentially injury-avoiding) "out" in case of emergency.
But more to the point, a Smith machine also traps the bar in a vertical track. While not everybody will feel comfortable with this vertical range of motion, it can be helpful for beginners who are familiarizing themselves with the motion, who don't have a spotter available or who feel pain doing normal barbell squats, because the motion-restricted bar allows you greater flexibility in where you put your feet.
Ultimately, the best way to see whether the Smith machine will suit you (or not) is to simply give it a try.
- ExRX.net: "Squat Analysis"
- ExRX.net: "Barbell Squat"
- Loyola University Medical Education Network: "Adductor Magnus"
- American Council on Exercise: "Back Squat"
- Debunking Fitness Myths: "Squats"
- American Council on Exercise: "Myths and Misconceptions: Lunges and Squats"
- Journal of Sports Sciences: "Kinematic and EMG Activities During Front and Back Squat Variations in Maximum Loads"
- ExRx.net: "Author's Analysis of Smith Squat"