Hack Squat

What is the Hack Squat?

The hack squat is a machine squat performed on an angled sled with your back supported against a pad and the shoulders under the yoke. The fixed path and back support let you push the quads hard without balancing a free bar, and foot placement lets you dial in a deep, knee-dominant range, making it a staple for adding quad size with heavy, controlled loading.

Muscles worked

Primary: Quads

The quadriceps are the prime mover, extending the knees to press the sled up; the supported back and fixed groove let you keep the knees traveling forward through a deep range that keeps the quads under heavy tension.

Secondary: Glutes

The glutes assist with hip extension out of the bottom of each rep.

Stabilizers

The trunk braces against the back pad, but the machine handles balance, so the quads can be pushed close to failure without stability limiting the set.

How to perform the Hack Squat

1. Position your back and shoulders against the angled pad and set your feet high and roughly shoulder width on the platform.
2. A higher foot placement biases the quads while keeping the knees from traveling too far forward over the toes.
3. Release the safety handles and let the knees bend to lower the sled along the fixed track under control.
4. Descend until the thighs reach at least parallel, keeping the whole back and hips pressed flat against the pad.
5. Do not let the hips round off the bottom of the pad as you go deep, which loads the lumbar spine.
6. Drive the platform back up through the mid-foot and heel, stopping just short of locking the knees to keep tension on the quads.

Suggested working range: 8–15 reps. Default progression: double progression.

Mechanics

A bilateral, machine-guided squat: shoulders under the pads and back braced, you bend the hips and knees to lower the sled along a fixed angled track, then extend the knees to press it back up. As a compound movement it trains the quads and glutes, but the back support and locked path remove balance from the equation, so it stays quad-dominant and lets you overload safely.

Form cues

• •Keep your whole back and hips flat against the pad through the entire rep. Don’t let your lower back peel off at the bottom.
• •Place the feet a touch lower on the platform to bias the quads, letting the knees travel forward over the toes.
• •Descend under control to at least parallel or deeper, then drive up through the whole foot without locking out and bouncing.

Common mistakes

• •Letting the hips round and lift off the bottom of the pad as you reach deep, loading the lumbar spine.
• •Placing the feet too low on the platform so the knees jam far past the toes.
• •Locking the knees out hard at the top and snapping the joint into hyperextension.
• •Letting the knees collapse inward on the drive up out of the bottom.

Variations & alternatives

• •Leg press: another back-supported machine that trains the quads and glutes heavy without balance demands.
• •Barbell back squat: the free-weight squat the hack squat supplements when you want to add quad volume with less stability cost.
• •Front squat: a barbell option that hits the quads with a similar upright, knee-forward emphasis.

Barbell Back Squat

Quads · Barbell

Leg Press

Quads · Machine

Bulgarian Split Squat

Quads · Dumbbell

Goblet Squat

Quads · Dumbbell

Leg Extension

Quads · Machine

Programming: sets, reps & when to use it

The hack squat works across an 8–15 rep range as a primary or secondary quad builder, and because the machine removes balance you can safely push sets close to failure and even run drop sets. Use a higher foot position and deeper range when you want maximum quad emphasis; place it after or in place of free-weight squats depending on the day’s focus.

Frequently asked questions