What muscles does the hack squat work?

Mainly the quads, with the glutes helping. Placing your feet higher on the platform shifts more of the work to the glutes.

Is the hack squat better than a barbell squat?

It is different. The hack squat isolates the legs and is easier to push hard safely; the barbell squat trains balance and the core as well and loads the whole body. Both build the quads.

Is the hack squat bad for your knees?

Not for most people with a controlled tempo and a depth they can reach comfortably. If your knees complain, move your feet higher on the platform and avoid locking out.

Why is my hack squat weaker than my leg press?

The hack squat carries part of your bodyweight and runs at a steeper angle, and it goes deeper. Most people move noticeably less weight on it than on a leg press.

Hack Squat: Muscles Worked and How to Do It

How to do a hack squat

Step into the machine with your back flat against the pad and your shoulders under the shoulder pads.
Place your feet about shoulder-width apart in the middle of the platform, toes turned out slightly.
Stand up to lift the weight off the hooks and release the safety handles.
Bend your knees and lower yourself slowly, keeping your back and hips against the pad, as deep as you can with your heels down.
Push through your whole foot to straighten your legs, stopping just short of locking your knees. Set the safeties again when you finish.

Cues that help

"Back glued to the pad": your hips do not slide away from it at the bottom.
"Knees over toes": let them travel forward; that is where the quad work comes from.
"Whole foot": heels stay down all the way.
"Soft knees at the top": stop just before locking out, then start the next rep.

Safety

Check where the safety stops sit before you load the machine, and set them just below the depth you squat to if your machine has adjustable ones.
Re-engage the safety handles before you step out, every set.
Do not snap your knees straight under heavy load; stop just short of lockout.

Common mistakes

Squatting only a quarter of the way. Most of the benefit of the hack squat is its deep range.
Heels lifting off the platform. Move your feet a little higher or widen your stance.
Hips coming off the pad at the bottom, which rounds the lower back.
Knees caving inwards on the way up.

Where to put your feet

Lower on the platform, with your knees travelling further forward, puts more of the work on the quads. Higher on the platform brings in more glutes and is easier on knees that do not like deep bending.

Start in the middle and adjust until you can reach a good depth with your heels down and your back flat against the pad.

Sets, reps and weight

For muscle: 3 to 4 sets of 6 to 12 reps.
Rest 2 to 3 minutes between sets.
Machines differ in friction and angle, so the weight on one hack squat does not translate to another. Compare yourself on the same machine.
Progress with reps first, then weight.

Variations and alternatives

Reverse hack squat: facing the pad, which works more glutes and hamstrings.
Pendulum squat: a similar machine with a swinging arc.
Barbell squat: the free-weight version, with more balance and core work.
Leg press: legs only, with your back fully supported.
Goblet squat: a light, free version for learning the pattern.

Tracking your hack squats

PushBeyond logs the weight and reps of each set and charts the history of the exercise. Its muscle map counts the hack squat for your quads, with your glutes as a helper.

Hack squat: muscles worked and how to do it

At a glance