Why Your Inner Thighs Burn After Deep Squats: Adductor Magnus vs Glute Max

If your inner thighs are sore after deep squats or leg presses, that is usually the adductor magnus doing real work. In the adductor magnus deep squat position, this big “inner thigh” muscle acts mostly as a hip extender, sharing the job with your glutes.

That changes how you should think about depth. This article sits inside our wider guide to range of motion and stretch-mediated hypertrophy, and it zooms in on one question: what happens at the hip when you go deep, and why the inner thigh joins in.

Why do my inner thighs hurt after squats and leg presses?

Most of the time, it is ordinary muscle soreness. You loaded a large muscle through a long range, probably more than usual, and it is complaining 24 to 72 hours later.

The surprise is which muscle is complaining. We tend to label the adductors “inner thigh squeezers” (the muscles you use in a hip adductor machine). But the adductor magnus is one of the largest muscles in the leg, and it is built more like a hip extensor than a squeezer.

A 2025 study used diffusion tensor imaging to map the muscle’s fibres in 15 young adults. Over 80% of its volume sat in the posterior and anterior-distal portions, and those portions had a longer moment arm for hip extension than for adduction. The whole muscle’s potential torque was over twofold greater for hip extension than for adduction (Takahashi et al., 2025). The scan was done with the hip in a neutral position, and the sample was young adults, so it describes the muscle’s design rather than a squat directly.

So when you stand up out of a deep hole, your glutes and a good chunk of your inner thigh are both pushing your hips forward.

What does hip flexion depth do to the glutes and adductor magnus?

Muscles pull with a lever, called a moment arm. A longer lever means more turning force at the joint for the same muscle force. Where that lever is longest changes with the angle of the hip.

A 1985 anatomical study combined data from ten autopsy specimens and twenty patients examined by CT to measure the hip extensors at angles from 0 to 90 degrees of hip flexion (Nemeth and Ohlsen, 1985). With the hip in its anatomical position, the moment arm was about 79 mm for gluteus maximus, 61 mm for the hamstrings and 15 mm for adductor magnus. As the hip flexed, the gluteus maximus moment arm decreased. The hamstring moment arm rose up to about 35 degrees, then fell. The adductor magnus moment arm rose up to about 75 degrees, then decreased.

Read that carefully. The glute moment arm is still bigger in absolute terms in this dataset at 0 degrees, and the paper reports trends rather than a hand-over where the adductor magnus becomes “the main” extensor. So the fair reading is: deeper hip flexion shifts some of the load toward the adductor magnus, not that the glutes switch off. It was a small, older, modelled dataset with significant differences between men and women, so treat it as a useful map, not a stopwatch.

The depth of a squat is the hip angle you reach at the bottom. A parallel squat and a squat to the floor differ a lot in hip flexion, and the muscle mix changes with it.

Do deeper squats really work the glutes more?

There is some evidence for it. Ten experienced lifters squatted at partial, parallel and full depth, and researchers measured surface EMG on four muscles. In the lifting phase, the gluteus maximus share of the total activity was 16.9% for partial squats, 28.0% for parallel and 35.4% for full-depth squats, with the parallel figure only borderline significant (p = 0.056). The other three muscles measured (vastus medialis, vastus lateralis and biceps femoris) did not differ across depths (Caterisano et al., 2002).

Three limits matter. It was ten people. Surface EMG measured only superficial muscles, so the adductor magnus was not in the data. And the numbers are relative shares, not absolute effort.

Relative effort tells a similar story from another angle. In ten strength-trained women, greater squat depth and heavier barbell load both raised hip extensor effort, and knee extensor effort rose with depth (Bryanton et al., 2012). The authors’ point is practical: heavier loads are needed to train the hip extensors, while the knee extensors need depth even at low loads.

Do deep squats build bigger inner thighs?

This is the question people actually care about, and one trial speaks to it directly. Seventeen young men were randomly assigned to full squats (8 men) or half squats (9 men) for 10 weeks, twice a week. MRI measured muscle volumes before and after (Kubo et al., 2019).

• Adductors: +6.2% with full squats, +2.7% with half squats.
• Gluteus maximus: +6.7% with full squats, +2.2% with half squats.
• Knee extensors: +4.9% and +4.6%, with no meaningful difference.

The gains in adductor and glute volume were significantly greater in the full squat group. Rectus femoris and hamstring volumes did not change in either group.

That fits the anatomy: the muscles that grew more with depth were the hip extensors. It also fits the broader review of range of motion, which concluded that full-range training has beneficial effects on lower body hypertrophy versus partial range (Schoenfeld and Grgic, 2020). Only six studies were included in that review, with a mostly male sample, so the claim is a leaning, not a law.

For the full squat-depth debate, including parallel versus deep, see our squat depth science guide.

Does leg press depth work the same way?

Less clear. The leg press is a different hip and knee path, and the data are thinner.

In a 2025 study, 23 resistance-trained people (average training age about 7 years) did unilateral leg presses for 8 weeks, one leg through roughly 5-100 degrees of knee flexion and the other through their maximum individual range, up to about 154 degrees. Quadriceps thickness grew in both legs with no meaningful difference, and the authors reported moderate to extreme evidence for no difference (Larsen et al., 2025).

That tells you the quads do not need extreme depth. It does not tell you about the glutes or adductors, because they were not measured.

The practical point is the hips. On a leg press, if you lower so far that your pelvis rolls off the pad (the “butt wink” on the machine), you stop gaining useful range for the hips and may load your lower back in a rounded position. Our leg press foot placement guide covers how to find the range your hips allow.

Which exercises load the adductor magnus most?

A 2026 modelling study had 15 injury-free people perform eight exercises, and an EMG-assisted model estimated forces in individual adductor muscles (Collings et al., 2026). The headline: the Copenhagen adduction exercise produced the highest forces across most adductors. But for the adductor magnus (ischiocondylar part, the hamstring-like back portion), deadlift, sumo deadlift, step-ups and squats were all in the top tier. The authors summarise it as high adductor magnus forces during hip extension-oriented exercises.

This is the same story from a different angle. The squat is not only a quad exercise, and the back part of the adductor magnus likes hip extension.

Muscle part or goal	Exercises that scored well in the 2026 model
Adductor magnus (back part, hip extension)	Deadlift, sumo deadlift, step-up, squat
Adductor longus and brevis	Copenhagen adduction (short and long lever)
Whole group, strongest overall	Copenhagen long lever

The sample was small and the forces were estimated by a model, not measured inside the muscle. Still, it supports a simple plan: squat deep and hinge for the adductor magnus, add direct adduction work if you want the other adductors.

How to use this in your training

Here is the practical version, without pretending the research gives precise numbers it does not.

1. Squat as deep as you can control. Pick the depth where your spine stays neutral and the bottom is stable. Film a set from the side.
2. Keep your tempo honest. Do not bounce out of the hole. A controlled descent keeps tension on the muscles that lengthen at the bottom.
3. Ramp up depth gradually. If you jump from parallel to full depth in one week, expect very sore inner thighs. Add a little range and a little volume at a time.
4. Use two exercise types. A deep squat or leg press for the knee and hip extension, plus a hinge (Romanian deadlift style) for the hip extensors in a different position. Our glute hypertrophy guide compares squats and hip thrusts in detail.
5. Add direct adductor work if it is a weak point. Our adductor training guide covers the machine and the Copenhagen options.

You can build a week around this with our free leg day plan, and check your weekly set count with the training volume calculator.

Is the soreness normal, or is it an injury?

Soreness after a new stimulus is expected. It tends to be dull, spread across both inner thighs, appear a day or two later and ease after a few days.

An injury looks different. The adductors are a common site of strains, and a deep squat puts them in a stretched position under load.

See a doctor or physiotherapist if you have sudden sharp groin pain, a pop, swelling or bruising, pain at rest, or soreness that lasts more than about two weeks. We cannot diagnose anything from an article, and pain that has a specific location and character deserves a proper exam.

What the research does not tell us

Be honest about the gaps.

• The 1985 moment arm data are old, small and modelled, and it did not test a loaded squat.
• The only trial linking depth to adductor and glute volume used 17 young men for 10 weeks.
• You will see claims online that the adductor magnus becomes the main hip extensor past 60 to 90 degrees. The moment arm study does not report that. It reports a rising adductor lever up to about 75 degrees and a falling glute lever.
• There is no trial of leg press depth on adductor size.
• Most subjects were young, healthy men. Results in women, older adults or people with hip pain may differ.

What you can say with reasonable confidence: depth shifts load toward the hip muscles, and in the one trial that checked, full squats grew the adductors and glutes more than half squats.

The bottom line

The adductor magnus is a large hip extender, so deep squats and leg presses load it alongside your glutes. That is why your inner thighs can feel it, and why full-depth squatting grew adductor and glute volume more than half squats in one MRI trial.

You do not need to chase extreme depth for your quads, since trained lifters grew them about the same across leg press ranges. You do want controlled depth if glutes and inner thighs matter to you. Squat as deep as you can own, progress gradually, and get sharp groin pain checked. If you want a structure to follow, start with our leg day plan and revisit the range of motion pillar for the bigger picture.