Hack Squat Machine

How to adjust

Set the shoulder pads so they sit snugly on your shoulders when you stand tall inside the machine, before releasing the safety handles.
Load weight plates onto the two posts on either side of the sled and secure them with plate collars.

Step into the machine, position your shoulders under the pads, back flat against the backrest, feet centered on the plate about shoulder-width apart.
Rotate or pull the safety handles to release the sled so it can move freely.
Inhale, bend your knees to lower along the fixed rail path, keeping your back against the pad.
Exhale, drive back up to the start position without locking the knees out.
If you run out of strength mid-set, don't keep grinding: drive up as far as you can, rotate the handles to set the safety catches, let the sled settle onto them, and then slide out from under it.
After your last rep, re-engage the safety handles before stepping out of the machine.

Always release the safety handles before descending and re-engage them right after your last rep — this is the main mechanism preventing the sled from dropping freely.
Do not lock the knees out at the top of the movement.
Load plates evenly on both sides and secure with collars so the sled doesn't tilt.