Hack Squat Machine: How Many Sets and Reps, and How to Progress

How many sets and reps to run on the hack squat machine, how to set your feet and tempo, plus an exact week-by-week plan for adding weight.

The hack squat is one of the few machines that lets you load your quads hard without balance and lower-back fatigue being the limiting factor. The fixed path makes progress easy to track, but it also makes it easy to overdo things because the movement feels safe. Here is how to set your sets, reps and progression so the work actually adds up.

What the machine does and does not do

Your back is supported and the path is guided, so most of the work lands on the quads, with some glute and adductor involvement. What the hack squat does not train is trunk stability and balance the way a barbell squat does. That is not a flaw - it is the reason you use it: you can push close to failure without the whole set falling apart on form.

Setup before your first set

Back and hips flat against the pad along their whole length, shoulders locked under the pads.
Feet hip-width or 5-10 cm wider, roughly mid-platform, toes turned out 10-20 degrees.
Knees track over the toes - never let them cave inward.
Feet lower on the platform means more quad and more knee load; feet 5-10 cm higher shifts work toward glutes and hamstrings.
Descend until your thigh is at least parallel to the platform. If your hips peel off the pad at the bottom, you went too deep - cut a couple of centimetres off your range.

How many sets and reps

Before your working sets, do 2-3 warm-ups: empty sled or 40 percent of your working weight for 8, then 65 percent for 5, then 85 percent for 3. Rest 60 seconds between them.

For muscle growth (the usual goal)

3-4 working sets of 8-12 reps, 2 to 2.5 minutes rest, leaving 1-2 reps in reserve (RIR 1-2). Take a set to true failure only on the last set, and not every session.

For strength

4-5 sets of 4-6 reps, 3 minutes rest, RIR 2. Chasing one-rep maxes on a machine makes little sense - the knee risk outweighs the payoff.

As a finisher on leg day

2-3 sets of 15-20 reps, 60-90 seconds rest. Use this version when you have already done your heavy work with squats or leg press.

Weekly volume: quads respond well to 10-20 total sets across all exercises. Let the hack squat cover 4-8 of those, split across 2 sessions per week with at least 48 hours between them.

How to progress, specifically

Double progression. Pick a range, say 8-12. Stay at the same load until you hit 12 clean reps in every working set.
Then add 5 kg (or 2 x 2.5 kg if the machine allows it). Your reps will drop to 9-10 - that is expected, and that is your new cycle.
Tempo before load. Lower for 2-3 seconds, pause 1 second at the bottom, drive up under control. If you cannot hold that tempo, the weight is too heavy.
Keep a log. Write down load, reps and RIR for every set. Without it, progression turns into guesswork.
If you stall 3 weeks in a row, run one week at 60-70 percent of your load with the same number of sets, then return to the old weight. Alternative: switch to a 6-8 or 12-15 range for 4-6 weeks.

Realistic expectations: a beginner can add 5 kg every 1-2 weeks for the first 2-3 months. After a year of training, that same 5 kg jump takes 4-6 weeks of work. That is not stalling, that is the normal curve.

If the number on the machine climbs while your depth quietly drops a couple of centimetres each week, you did not progress - you just shortened the exercise.

Common mistakes

Huge loads through half the range, with a bounce out of the bottom.
Heels lifting - move your feet 5 cm forward instead of ignoring it.
Every set to failure, every session. That wrecks recovery and adds nothing.
Slamming the knees into full lockout at the top - stop a few degrees short.
Changing foot position every session, so you never know what you are comparing.

When to see a doctor

See a doctor, not a coach, if you have:

sharp knee pain lasting more than 2 weeks, or pain that shows up outside training;
knee swelling, locking, or a feeling that the joint gives way;
lower back pain radiating down the leg, with numbness or foot weakness;
dizziness, head pressure or chest pain during a set;
a previous knee, hip or spine surgery, or a known disc herniation - clear your allowed depth and load before adding this exercise.

The short version

Size: 3-4 sets of 8-12, 2-2.5 minutes rest, RIR 1-2. Strength: 4-5 sets of 4-6, 3 minutes rest.
Warm up with 3 sets: 40 percent x 8, 65 percent x 5, 85 percent x 3.
Double progression: hit the top of the rep range in all sets, then add 5 kg.
At least parallel depth, 2-3 second descent, hips stay glued to the pad.
Fix a 3-week stall with one lighter week at 60-70 percent, not with extra sets.