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Compare exercises side by side

Choosing between two exercises? Compare their setup and muscles worked, then explore a detailed comparison to decide how they fit your training.

Anatomical illustration of a man lowering and pressing a hack squat sled, with the front thighs and glutes highlighted.

Hack squat

The hack squat is a machine squat performed with the back supported and the shoulders under a moving sled.

Equipment in the guide
hack squat machine
See technique guide
Two-frame anatomical illustration of a barbell back squat on a white background. On the left a muscular male figure stands upright, seen square from the front, with a loaded barbell across his upper back and both hands gripping it wide; from the front the bar's height on the back cannot be read. The fronts of both thighs are shaded red, as is a strip down the front of each shin. On the right the same figure is at the bottom of the rep, seen from the side and a little behind, hips at or below the knees in a deep squat with the feet flat and the toes turned out slightly; from this angle the red shading covers the fronts of the thighs and the inner thigh running up toward the groin. The buttock is in view in that frame and is not shaded, and nothing on the back of the thigh is shaded in either.

Barbell back squat

A barbell back squat is a bilateral squat performed with a barbell resting across the upper back.

Equipment in the guide
barbell, squat rack
See technique guide

How these exercises compare

Choose the hack squat when you want a squat with back support and a guided sled. Choose the barbell back squat when you want to train the free-weight lift itself. Both involve the knees and hips, but the support and balance demands differ. Neither is a universal winner.

Support
Hack squatYour back rests against a pad beneath shoulder pads.Barbell back squatYou support the bar across your upper back without a back pad.
Load path
Hack squatA sled follows the machine's rails.Barbell back squatYou balance a free bar over your base of support.
Range of motion
Hack squatUse the range the machine allows while your feet and pelvis stay supported.Barbell back squatDepth depends on the squat you can control with your chosen stance and bar position.

When to choose each exercise

Hack squat

You want supported leg work and have a machine that fits your movement. It can fill a squat slot or provide additional leg work after a free-weight lift.

Barbell back squat

You want to improve your barbell squat or prefer a free-weight movement. You support the bar and control its path, using a rack and appropriate safeties.

Read the full comparison
Muscles worked

The highlights locate muscles involved in each exercise. They do not measure effort, muscle growth or how closely the exercises match.

Hack squat

Front
Front — Schematic surface view. Some muscles are partly visible or not shown.
Back
Back — Schematic surface view. Some muscles are partly visible or not shown.

Primary

Secondary

Select a muscle name to locate it.

Schematic surface view. Some muscles are partly visible or not shown.

The quadriceps are the main target; the gluteus maximus and adductor magnus assist hip extension on the sled.

Barbell back squat

Front
Front — Schematic surface view. Some muscles are partly visible or not shown.
Back
Back — Schematic surface view. Some muscles are partly visible or not shown.

Primary

Secondary

Select a muscle name to locate it.

Schematic surface view. Some muscles are partly visible or not shown.

Grouped by what the training evidence measured, not ranked: the MRI trial this page leans on tested each muscle group against its own baseline and never compared one against another, so no ordering is claimed here. The hamstrings are under secondary because they were measured and did not grow, but they stay on the list because they do work during the lift, as hip extensors. Rectus femoris is there for a different reason: one trial measured no growth and a second did find it, so that one is unsettled rather than settled either way. The trunk extensors and the calves are absent because neither trial measured them, which is not the same as ruling them out.

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