What Muscles Do Squats Work?
Squats get called a leg exercise, and that is true as far as it goes. It just misses most of what is happening. So what muscles do squats work, exactly? Once you add up everything that has to fire to lower you down and stand you back up under control, the list runs from your feet to your upper back.
Squats work the quadriceps, glutes and adductors as the main movers, with the hamstrings, calves, core and spinal erectors working hard to keep you stable and upright. That is why squats are usually described as a full lower body exercise rather than a thigh exercise.
The bit most articles get wrong: your hamstrings and your abs are both routinely listed as muscles squats train hard. Neither claim really holds up. There are honest sections on both below, because knowing what squats do not cover tells you what else your week needs.
Every muscle a squat uses, at a glance
Here is the whole picture before we go through it properly. “Prime mover” means the muscle actively producing the movement. “Stabiliser” means it is working hard, often very hard, but holding a position rather than creating the motion.
| Muscle | Where it is | Role in a squat |
|---|---|---|
| Quadriceps | Front of thigh | Prime mover, straightens the knee |
| Gluteus maximus | Buttocks | Prime mover, straightens the hip |
| Adductor magnus | Inner thigh | Prime mover, assists hip extension |
| Gluteus medius | Side of hip | Stabiliser, stops knees caving in |
| Hamstrings | Back of thigh | Stabiliser, less active than people assume |
| Erector spinae | Either side of the spine | Stabiliser, keeps your back from rounding |
| Core (deep and outer) | Trunk | Stabiliser, braces the middle |
| Calves (soleus mainly) | Lower leg | Stabiliser, controls the shin over the foot |
| Upper back and shoulders | Between shoulder blades | Only when holding a weight in front or on the back |
If you are counting, that is nine muscle groups for one movement. It is the clearest example of what people mean by a compound exercise, and it is why a beginner routine can get a long way with very few movements.
The three muscles doing the actual work
Quadriceps
Four muscles on the front of your thigh, and the reason your legs shake on the last rep. Their job in a squat is knee extension, which is the straightening of your knee as you come back up.
Squat depth changes how much they get. Coming down to roughly parallel, where your hip crease drops to about knee height, loads them considerably more than a shallow quarter squat. This is the single biggest reason half-squats feel easy: you are cutting out the range where the quads work hardest.
Gluteus maximus
The largest muscle in the human body, and the main hip extensor. It contributes most in the bottom portion of the squat, in the first drive out of the hole, and it tails off as you approach standing.
Glute involvement climbs as you go deeper and as you sit your hips further back. If someone tells you squats are all quads and no glutes, they are describing a shallow squat with an upright torso, not squats in general.
Adductor magnus, the one nobody mentions
Your adductors are your inner thigh muscles, and most lists file them under “also worked a bit”. That undersells adductor magnus badly. It attaches from the pelvis to the back of the thigh bone, and functionally it behaves as a hip extensor, meaning it helps drive you up out of the bottom alongside your glutes.
Practically, this is why inner thighs are frequently the sorest part of a beginner after their first proper squat session, and why people are confused by it. Nothing has gone wrong. You have just used a muscle you did not know was involved. If that soreness is what brought you here, this covers what actually helps with it.
The muscles holding you together
These do not move you. They stop you from folding, and they are working the entire time the weight is on you.
Gluteus medius
Sits on the side of your hip. Its job during a squat is stopping your knees from drifting inward toward each other. If you have ever been told to “push your knees out”, you were being told to use your gluteus medius. Weakness here is one of the most common reasons beginner squats look wobbly.
Erector spinae and the core
The erectors run either side of your spine and hold your back from rounding forward. Your abs and obliques work with them, bracing the trunk so that the force from your legs actually reaches the floor instead of being lost in a collapsing middle.
This is genuine, meaningful core work. It is also a completely different kind of core work from crunches, which we will come back to.
Calves
Mostly the soleus, the deeper of the two calf muscles. It controls how far your shin travels forward over your foot as you descend. Squats will not build calves the way calf raises do, but stiff, restricted calves are a very common cause of heels lifting off the floor at the bottom of a squat.
Upper back and shoulders
Only relevant once you are holding weight. A goblet squat with a dumbbell at your chest makes your upper back and shoulders work isometrically to stop the weight pulling you forward. A bodyweight squat does essentially none of this.
Do squats work your abs?
Yes, but as a bracing muscle, not as a muscle being trained through its range. Your abs work in a squat the way they work when you carry something heavy: holding a rigid position against a force trying to bend you.
That is worth having. It is not the same stimulus as flexing your spine against resistance, and it will not on its own do what direct core work does. If your goal includes visible abs, it is worth being clear that no exercise, squats included, reduces fat over the stomach specifically. That is covered properly in how to get a flat stomach.
So squats belong in your week, and so does a dedicated core session. They are not substitutes for each other.
Do squats work your hamstrings? Honestly, not much
Almost every article on this topic lists hamstrings as a prime mover. The reality is more awkward than that, and it matters for how you build your week.
The hamstrings cross two joints. They extend the hip, which helps in a squat, but they also bend the knee, which opposes what you are trying to do in a squat. Those two roles partly cancel each other out. The hamstrings stay under fairly steady, moderate tension throughout the movement rather than contracting and shortening the way the quads and glutes do.
What this means in practice: squatting alone leaves your hamstrings comparatively undertrained. If squats are your only leg exercise, you are building a lopsided lower body. Add a hip hinge movement, meaning something where your hips travel back and your knees stay relatively straight. Glute bridges are the easiest starting point, and Romanian deadlifts with dumbbells are the natural progression. Both appear in the dumbbell leg workout.
How different types of squats change the muscles worked
Every squat variation trains the same broad set of muscles. What changes is the emphasis, and the shifts are large enough to be worth choosing deliberately rather than picking whichever version you saw first.
| Variation | Shifts emphasis toward | Good for |
|---|---|---|
| Bodyweight squat | Balanced, light throughout | Learning the pattern, daily movement |
| Goblet squat | Quads, plus upper back holding the weight | The best first loaded squat for most beginners |
| Sumo squat | Adductors and glutes | Inner thigh work, people with stiff ankles |
| Split squat | One leg at a time, gluteus medius | Fixing side-to-side differences, balance |
| Bulgarian split squat | Glutes of the front leg, heavily | Serious leg work with very little equipment |
| Front squat | Quads and upper back | Later on, with a barbell |
| Back squat | Glutes and spinal erectors | Loading heavy, once form is solid |
| Wall sit | Quads, held still | Building tolerance when knees are cranky |
Two things worth pulling out of that table.
Stance width is the biggest single lever. Taking a wider stance with toes turned out, as in a sumo squat, meaningfully increases adductor and glute demand. A narrower stance pushes work toward the quads. You do not need new equipment to change what a squat trains, you need to move your feet.
Single-leg variations are not just harder versions. Standing on one leg forces your gluteus medius to control the pelvis in a way a two-legged squat never will. That is a different training effect, not simply more of the same.
How to actually feel the right muscles working
Knowing the anatomy is not much use if your squat does not reach the muscles it should. Four adjustments cover most beginner problems.
- Go deeper, within reason. Aim for thighs roughly parallel to the floor. Both quads and glutes get noticeably more work at depth, and shallow squatting is the most common reason people feel nothing.
- Sit back, not just down. Push your hips backward as you descend, as if reaching for a chair behind you. Straight down loads the quads almost exclusively.
- Push the floor apart. As you stand up, imagine spreading the floor sideways with your feet. This switches the gluteus medius on and keeps your knees tracking over your toes.
- Pause for a second at the bottom. Removing the bounce means the muscles, not momentum, do the work. It also makes a bodyweight squat considerably harder without any weight.
If your heels lift at the bottom, that is usually ankle stiffness rather than weakness. Standing with your heels on a folded towel is the standard fix, and working on ankle mobility solves it properly over time.
If squats bother your knees
Squats do not inherently damage knees. The old advice about knees never travelling past the toes has not held up, and for most people some forward knee travel is normal and necessary, particularly if you have long thighs.
That said, if squatting hurts, the useful adjustments are: reduce depth to the range that does not hurt and rebuild from there, widen your stance slightly, and slow the lowering phase down. Box squats, where you sit back to a chair and stand up again, let you control depth precisely. There are more joint-friendly options in the low-impact beginner workout.
Pain that is sharp, that swells, or that persists after you stop is not a form problem to solve on your own. See a physiotherapist or your GP.
How many squats, and how often
For a beginner, two to three sessions a week with squats in them is plenty, with a day between them. Three sets of eight to twelve bodyweight reps is a sensible starting point.
Once thirty comfortable bodyweight reps stops being difficult, adding reps is no longer the most efficient path. Add load with a goblet squat, or move to single-leg work. Both give you more stimulus in less time. If you want a sense of what load is reasonable for your bodyweight, the strength calculator will give you a starting range.
A light set of bodyweight squats can also be done daily without much thought, and that is exactly how they appear in the seven exercises to do every day. Daily gentle squatting and twice-weekly hard squatting are different things with different purposes.
Where squats fit in your week
Squats cover a genuinely large share of your lower body in one movement, which is why nearly every sensible beginner programme includes them. What they do not cover is the hamstring-dominant hinge pattern, direct calf work, and anything for your upper body.
Build around them rather than on them alone. The beginner leg workout at home pairs squats with the hinge work they are missing, the full-body beginner routine shows how they slot into a complete session, and which muscle groups to work out together explains the pairing logic if you are building your own plan.
One last thing: warm up first. Squatting cold is where a lot of avoidable knee and lower back grumbles come from. Five minutes is enough, and the warm-up routine covers it.
Squats train the glutes but skip the gluteus medius. That gap is covered in upper glute exercises.
Squats on two legs hide side-to-side differences. The single leg squat progression exposes them and gives you a way to close the gap.
Squats leave the hamstrings undertrained. The hamstring exercises at home guide covers the hinge and curl work they miss.
Squats work the adductors only as stabilisers. Inner thigh exercises covers how to load them directly.
For single-leg options when lunges do not suit you, see lunge alternatives.
A hinge is not a squat. The good morning exercise teaches the difference.
Frequently asked questions
What muscles do squats work the most?
The quadriceps and gluteus maximus, with adductor magnus contributing far more than most people realise. Those three produce the movement. Everything else is stabilising.
Do squats work your stomach?
Your abs brace hard during a squat to keep your trunk rigid, so they are working. They are not being trained through a range of motion the way they are in direct core exercises, and squats will not reduce belly fat specifically.
Do squats work your glutes or your quads more?
It depends on how you squat. Deeper squats with the hips pushed back and a wider stance favour the glutes. Shallower, more upright squats with a narrow stance favour the quads. Both are always involved.
Are squats enough for leg day on their own?
No. Squats leave the hamstrings relatively undertrained because the hamstrings work as stabilisers rather than movers. Pair squats with a hinge movement such as glute bridges or Romanian deadlifts, and add calf work if that matters to you.
Why do my inner thighs hurt after squats?
Because adductor magnus is a real contributor to hip extension in a squat, not a minor helper. Inner thigh soreness after early squat sessions is normal and usually settles within a few sessions as you adapt.
Do bodyweight squats build muscle?
Early on, yes, particularly if you are new to training. Once you can do around thirty comfortable reps the stimulus fades, and adding load or switching to single-leg variations will do more than adding further reps.
Is it bad if my knees go past my toes when I squat?
Generally no. Some forward knee travel is normal, and it is unavoidable for people with longer thighs. Deliberately blocking it usually just forces more bend at the hips and shifts stress into the lower back instead.
This article is general information for healthy adults, not medical advice. If you have a knee, hip or back condition, or you are recovering from an injury, check with a doctor or physiotherapist before starting squats. General activity guidance from the NHS, Physical activity guidelines for adults aged 19 to 64.
