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Hack squat

Also called machine hack squat, sled hack squat, hack squats.

What is a hack squat?

The hack squat is a machine squat performed with the back supported and the shoulders under a moving sled. It mainly trains the quadriceps, while the gluteus maximus and adductor magnus help extend the hips.

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

How do you perform a hack squat?

Set up

  1. Step onto the platform, place your back and hips against the pad, and set your shoulders securely beneath the shoulder pads.
  2. Place both feet about shoulder width on the platform, straighten the sled and release the safety stops.

Execution

  1. Bend your knees and hips together, keeping your whole feet on the platform and your knees following your toes.
  2. Descend only as far as you can without your pelvis rolling away from the back pad.
  3. Press the platform away until you are standing tall on the sled, then reset the safety stops after the final rep.

Common mistakes

  • Letting the pelvis curl off the back pad

    That changes the supported position the machine is meant to provide. Stop the descent before the pelvis lifts.

  • Letting the heels rise

    A shifting foot makes the base less stable. Adjust foot position or depth so the whole foot stays planted.

  • Forgetting the safety stops

    The sled should be secured before you step out from under it.

Where it fits in a session

Use it as a main squat pattern or after free-weight squats as additional leg work.

Set foot position and depth consistently so changes in logged load reflect the same movement.

Muscles worked

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.

Variations

  • Anatomical illustration of a 45-degree sled leg press, shown as two frames side by side. In both, a grey muscle-anatomy figure lies back on the angled seat of a plate-loaded sled machine with a weight plate on the carriage and both feet flat on the footplate. On the left the legs are almost straight at the top of the push, the sled high on the rails; on the right the carriage has come down and the knees are bent past a right angle, thighs close to the chest. The muscles of the thighs are highlighted in red along their whole length, the upper inner thigh at the hip most strongly; the buttocks are pressed against the pad and are not visible.
    Leg pressUses a foot platform and guided sled while the torso stays seated rather than standing under shoulder pads.
  • 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 squatRemoves the back pad and fixed sled path, so the lifter balances the bar.
  • Pendulum squat — The loaded carriage moves through an arc instead of sliding on rails.

Related tools

Frequently asked questions

What muscles does the hack squat work?

The quadriceps are the main target. The gluteus maximus and adductor magnus also help straighten the hips as the sled rises.

How deep should you hack squat?

Descend while your feet remain planted, your knees track with your toes and your pelvis stays against the pad. Stop before any of those positions changes.

Is a hack squat the same as a leg press?

No. Both use a guided sled, but a hack squat supports the back while the shoulders move under pads; a leg press keeps the torso seated while the feet move the platform away.

Where should your feet go on a hack squat?

Start around shoulder width with the feet high enough that the heels stay down. Machine geometry and body proportions differ, so adjust from that position without forcing one universal mark on the platform.

Sources

  1. Anatomy, Bony Pelvis and Lower Limb: Thigh Quadriceps Muscle. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK513334/
  2. Anatomy, Bony Pelvis and Lower Limb, Gluteus Maximus Muscle. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK538193/
  3. Anatomy, Bony Pelvis and Lower Limb: Thigh Adductor Magnus Muscle. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK534842/

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