Hack squat

Shoulder pads locked, heels mid-plate, knees track over toes.

family=hack squatpattern=squatforce=pushmechanic=compoundequipment=machine

Muscles

muscle emphasis · training guidance

quadsPRIME
glutes68
Primary
quads
Supporting
glutes

Mechanics

Pattern
squat
Equipment
machine
Geometry
90° Alignment
Target feel
Quads load through full range without lower back involvement.
Progression
Add load when depth and knee tracking hold across all sets.
Regression
Leg press if shoulder pad position is uncomfortable.

Watch for

  • Stopping short of parallel — cuts quad recruitment
  • Heels raised high — shifts load off quads
  • Knees caving inward on the drive

Equipment context

The machine fixes the movement path, reducing stabilizer demand and letting you focus on the target muscle.

Substitutions

Progression ladder

  1. Beginner / regression: Leg press if shoulder pad position is uncomfortable.
  2. Standard: Hack squat
  3. Advanced / progression: Add load when depth and knee tracking hold across all sets.

Atlas metrics

Movement pattern
squat
Primary target
quads
Supporting muscles
glutes
Equipment
machine
Joint geometry
90° Alignment
Alternatives
3 substitutions

Evidence & limits

Last reviewed against peer-reviewed biomechanics references. Exercise descriptions are framed as training guidance, not medical advice.

Source: ExRx.net Exercise & Muscle Directory

Eccentryx is fitness software. It is not a medical device and is not intended to diagnose, treat, cure, or prevent any disease, injury, or medical condition. Consult a licensed physician before beginning any exercise program.

Try these tools

FAQ

How do I set up Hack squat?
Shoulder pads locked, heels mid-plate, knees track over toes.
What should I feel during Hack squat?
Quads load through full range without lower back involvement.
What are common mistakes with Hack squat?
Stopping short of parallel — cuts quad recruitment; Heels raised high — shifts load off quads; Knees caving inward on the drive
How do I progress Hack squat?
Add load when depth and knee tracking hold across all sets.
What can I do instead of Hack squat?
Leg press, Goblet squat, Pendulum squat
Hack squat verified exercise line-art diagram.
The movement · Knee (drive) 96°→18°
FgFe96→18° Knee (drive)124→124° Back (braced)10→8° Hip

Hack squat: squat pattern, 2400 ms rep trace, engine-derived.

Train Hack squat in Gym Mode → Browse the public Atlas →