Hack Squat: the machine squat for bigger quads
The hack squat is a machine squat done on a 45-degree angled sled with your back supported, biasing the quads while sparing the lower back. It's the easiest way to load the quads hard without a barbell on your spine.
How to do the hack squat
- Set the load and step into the machine, back and shoulders against the pad.
- Place your feet shoulder-width on the platform — lower/centre for more quad, higher for more glute.
- Unlock the safety handles and brace your core.
- Lower under control by bending the knees, keeping your back flat on the pad and heels down, to at least parallel.
- Drive through your heels back up without locking the knees hard.
Keep your knees tracking over your toes throughout.
Sets and reps
A machine compound — you can push it harder than free squats because the path is fixed.
| Goal | Sets | Reps |
|---|---|---|
| Strength | 3–4 | 6–8 |
| Hypertrophy | 3–4 | 10–15 |
| Endurance | 2–3 | 15–20 |
Muscles worked
Primary — the quadriceps.
Secondary — the glutes, hamstrings, adductors, and calves, with the emphasis shifting based on foot placement.
Common mistakes
- Feet too low — your heels lift at depth.
- Feet too high when you want quads — it shifts the work to the glutes and hams.
- Knees caving in — usually too much weight; track them over the toes.
- Letting the back come off the pad — keep it pinned.
- Partial depth — go to at least parallel for the full effect.
Variations and alternatives
- Reverse hack squat (facing the machine) — more glute and hamstring.
- Smith-machine hack squat and foot-placement variations.
For other machine quad options, see the pendulum squat and leg extension, or program it onto a leg day in a split like PPL.
Common questions
What muscles do hack squats work?
Primarily the quads, with the glutes, hamstrings, and adductors assisting depending on foot placement.
Where should I place my feet on the hack squat?
Low and centred for maximum quads; higher and wider to bring in more glutes and hamstrings.
Are hack squats better than regular squats?
They isolate the quads more and spare the lower back, but they don't train balance and stabilisers like a free-weight squat. They're a great complement, not a full replacement.
Are hack squats bad for your knees?
Done with proper depth, knees tracking over the toes, and sensible load, they're fine for most people. Avoid letting the knees cave or your heels lift.
Setting your squat numbers? Work back from a recent hard set — estimate your max without testing one, or use the 1RM calculator.