Hack Squat

Move · Resistance Training · Movement, Typed Supps

Your back is held by a pad, so the quads fail before anything else gives out.

Stage by stage

Set-up (Foot placement sets leverage): Where the feet sit on the platform is the only thing controlling the knee and hip moment arms, since the sled path itself cannot change.
During the set (Fixed path, fixed vector): With the back pad taking the trunk and balance demand, the quadriceps carry the load through a resistance line that never shifts.
Immediately after (Local quad failure): Sets end on quadriceps fatigue rather than on erector fatigue or technical breakdown, so the systemic cost is lower than a heavy barbell squat.
Months later (Quadriceps cross-section grows): Loading the quads at long muscle lengths under support builds thigh size over two to three months, while joint loading still depends on depth and foot position.

Muscles trained

Primary: quads
Secondary: glutes

Intensity

5 METs (Resistance (weight) training, squats , slow or explosive effort).

Time to effect

Weeks: The fixed path takes the guesswork out of balance, so within a couple of weeks most people are pushing meaningfully more weight than they could stabilize with a free-weight squat.
Months: Quad size and strength typically build over 2 to 3 months of progressive loading, similar to other quad-dominant machine work.

Related supplements

Creatine Monohydrate

Common myth

"Machine hack squats are automatically easier on the knees than a barbell squat." In reality: The fixed sled path can actually increase shear force at the knee for some people, particularly with the feet placed low on the platform or the depth pushed past what the joint comfortably tolerates. The machine changes which stabilizers get challenged, it doesn't automatically reduce knee stress.