Hack Squat
The hack squat loads a squat pattern onto an angled sled, with your shoulders braced under pads and your back supported against the backrest the whole rep. It isolates the quads more directly than a free-standing squat because the machine handles your balance for you, which makes it a good option for beginners building leg strength or lifters chasing quad size without extra lower-back load.
Why it works
Because the sled travels on a fixed track and your back stays pinned to the pad, the hack squat removes most of the balance and bracing work a free squat demands, letting your quads take on more of the load per set. The angled path also keeps your torso more upright than a barbell squat, which shifts emphasis toward the quads and away from the hips and lower back. That combination makes it a reliable way to push quad volume when you want the muscle worked hard without the technical demands of a loaded barbell squat.
Set up
- Position your shoulders under the pads and your back flat against the backrest.
- Set your feet shoulder-width on the platform, slightly forward of your hips.
- Release the safety handles only once your feet are set and your core is braced.
- Choose a foot position lower on the platform for more quad emphasis, higher for more glute and hamstring involvement.
How to do it
- Unlock the sled and let it settle with your knees slightly bent.
- Bend your knees and hips to lower the sled, keeping your back flat on the pad.
- Descend until your thighs are at least parallel to the platform.
- Push through your whole foot to drive the sled back up.
- Extend your knees and hips fully at the top without locking out hard.
- Reset your breath and repeat for the next rep.
Form cues
- Keep your back flat against the pad the entire rep.
- Drive through your whole foot, not just your toes.
- Let your knees track in line with your toes as you descend.
- Control the sled down, don't let it drop.
Breathing: Inhale and brace your core as you lower the sled, then exhale as you drive back up to the top.
Common mistakes
Letting the lower back round or lift off the pad at the bottom of the rep.
Fix: Stop your descent at the depth where your lower back can stay flat against the pad, even if that means a smaller range of motion at first.
Placing the feet too high on the platform, which shifts the work off the quads and toward the hips.
Fix: Set your feet closer to shoulder width and mid-platform, then adjust higher only if you're deliberately targeting glutes and hamstrings.
Locking the knees out hard at the top of every rep.
Fix: Stop just short of full lockout and keep the muscles under tension instead of resting on your joints between reps.
Bouncing out of the bottom position to use momentum instead of muscle to reverse the sled.
Fix: Come to a controlled stop at your deepest comfortable depth before driving back up; a bounce off the joints, not the muscle, is doing the work if you're rebounding hard.
How to program it
- As a guided quad exercise, 3 to 4 sets of 8 to 12 reps once or twice a week fits well in a leg session, either as your main quad movement or paired after a free squat.
- Because the machine supports your back and balance, it holds up well to higher rep ranges (12 to 15) if you're training for muscle size rather than strength.
- Place it after your primary squat or lunge work if you're using it to add extra quad volume rather than as the day's first heavy lift.
- If your gym's sled travels on a steep angle, expect more forward knee travel than a barbell squat; start lighter than you'd guess from your squat numbers until you know how the machine feels.
Safety notes
- Never remove your shoulders from under the pads or your back from the backrest until the sled is fully racked and locked.
- If your knees track inward as you fatigue late in a set, stop the set rather than pushing through with breaking form.
- Check that the safety catches are engaged and within reach before you unrack the sled, so you always have a way to bail out under a weight you can't finish.
Exercise profile
- Force
- Push
- Mechanics
- Compound
- Category
- Strength
Frequently asked questions
How many sets and reps should I do for hack squats?
Three to four sets of 8 to 12 reps works well for most people, either as a main quad exercise or added after a free-standing squat.
What can I do instead of the hack squat if my gym doesn't have the machine?
A dumbbell squat trains a similar knee-dominant pattern without needing the sled, and a leg press covers the same supported, machine-based approach.
Hack squat vs leg press, what's the difference?
The hack squat keeps you upright with your back against a pad while your legs move under you, closer to a real squat pattern. The leg press has you seated and reclined, pushing a platform away from your body, which shifts more of the work toward the hips depending on foot placement.
Why do my knees hurt on the hack squat?
Knee discomfort here usually comes from foot placement too far forward or descending deeper than your mobility allows. Move your feet slightly forward on the platform and stop your descent at a depth where your knees stay pain-free.