Squats are a lower-body exercise where you bend your hips and knees to lower your body toward the ground, then push back up to standing. They’re one of the most effective exercises for building strength in your legs, glutes, and core, and they show up in nearly every strength training program, physical therapy plan, and sports performance routine for good reason.
How the Movement Works
A squat is built around two main joints: the hips and the knees. As you lower yourself, both joints bend (flex), and as you stand back up, both joints straighten (extend). During the descent, gravity is pulling you down, and your muscles are working to control the speed. During the ascent, those same muscles fire harder to push you back to the top.
Your trunk plays a bigger role than most people realize. The muscles of your core and lower back have to stay engaged throughout the movement to keep your spine stable and your torso upright. If your upper body tips too far forward, it shifts more demand onto your lower back and hips. The relationship between how much your torso leans and how much your shins angle forward actually determines how the effort is distributed between your hip muscles and knee muscles.
Muscles Squats Target
Squats are a compound exercise, meaning they work multiple muscle groups at once. The primary movers are your quadriceps (the front of your thighs), your glutes (the large muscles of your buttocks), and your hamstrings (the back of your thighs). Your core muscles, lower back, and even your upper back all contribute as stabilizers.
Muscle activation data gives a clearer picture of what’s happening. During the upward phase of a squat to 90 degrees of knee bend, the quadriceps fire at roughly 53 to 56% of their maximum capacity, while the glutes hit about 56% and the hamstrings reach around 58%. On the way down, the effort drops significantly: glute activation falls to about 23%, and the quadriceps settle around 41%. This makes sense because the lowering phase is about controlling gravity rather than generating force. The standing-up phase is where the real work happens.
How deep you squat also matters. Deeper squats (around 140 degrees of knee flexion, well below parallel) increase quadriceps activation slightly compared to a parallel squat, while glute activation is actually a bit higher at the shallower depth. Stance width changes things too. A wider stance increases inner thigh (adductor) activity during the upward phase by roughly 50% compared to the downward phase.
Benefits Beyond Muscle
Building stronger legs is the obvious payoff, but regular squatting delivers benefits that go well beyond visible muscle. Squats are one of the most effective exercises for improving bone mineral density at the hip and lumbar spine, two of the most fracture-prone areas as people age. Progressive resistance training programs that include squats have been shown to increase both lean mass and bone density at these sites, reducing the risk of hip and vertebral fractures.
Squats also improve functional movement patterns you use every day: sitting down and standing up, climbing stairs, picking things up from the floor. Strengthening these patterns helps maintain independence as you get older and reduces injury risk during sports or physical labor. Because squats demand so much muscle mass at once, they also trigger a strong hormonal response. High-intensity squat sessions with sufficient volume (six or more sets) produce significant post-exercise increases in growth hormone, which supports muscle repair and recovery.
Common Squat Variations
The bodyweight squat is the simplest version. You stand with feet roughly shoulder-width apart, lower yourself by bending your hips and knees, and stand back up. No equipment needed, and it’s where most beginners should start.
The goblet squat adds a dumbbell or kettlebell held at chest height. The front-loaded weight naturally encourages an upright torso, making it easier to maintain good form. It’s an excellent bridge between bodyweight squats and barbell work.
The back squat places a barbell across the upper back. This allows you to load the movement with significantly more weight than other variations, making it the go-to for building maximum strength. Because the weight sits behind your center of gravity, your torso tends to lean forward more, which increases the demand on your hips and lower back.
The front squat positions the barbell across the front of the shoulders. Like the goblet squat, the front-loaded weight keeps your torso more upright and shifts emphasis toward the quadriceps. Both front-loaded variations also place a stronger demand on the core and upper back compared to back squats, since those muscles have to work harder to prevent you from folding forward.
Getting Your Form Right
Stance width is more personal than most people think. Research categorizes a narrow stance as roughly shoulder width, a medium stance as about 1.25 to 1.5 times shoulder width, and a wide stance as 1.5 to 2 times shoulder width. There’s no single “correct” width. Your hip anatomy, leg length, and mobility all influence what feels natural and allows you to reach good depth without discomfort.
A few principles hold true regardless of stance. Your feet should angle outward slightly (typically 15 to 30 degrees), and your knees should track in the same direction as your toes throughout the movement. As you descend, think about sitting back and down rather than just bending your knees forward. Keep your chest up and your weight balanced across your whole foot, not shifted onto your toes.
Depth is another variable with some flexibility. A parallel squat, where your thighs reach roughly horizontal, is the standard benchmark. Going deeper increases the range of motion and slightly changes which muscles work hardest, but it also requires more hip and ankle mobility. If your lower back starts to round (often called “butt wink”) at the bottom, you’ve gone past what your current mobility allows. Working on ankle and hip flexibility over time will let you squat deeper safely.
Who Should Squat
Almost everyone. Squats are used in rehabilitation settings for people recovering from knee or hip injuries, in strength programs for competitive athletes, and in general fitness routines for people who just want to stay healthy. The movement pattern is fundamental to human biomechanics. You squat every time you sit in a chair.
If you’re new to exercise, start with bodyweight squats and focus on controlling the descent for two to three seconds before standing back up. Once you can do three sets of 15 with good form, you’re ready to add weight. Progress to goblet squats first, then to barbell variations if your goals call for heavier loading. The key with any version is consistency: squatting two to three times per week, with gradual increases in difficulty, produces steady gains in strength, muscle, and bone density over months and years.