Hack squat
Shoulder pads locked, heels mid-plate, knees track over toes.
family=hack squatpattern=squatforce=pushmechanic=compoundequipment=machine
Muscles
- 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
Related exercises
Progression ladder
- Beginner / regression: Leg press if shoulder pad position is uncomfortable.
- Standard: Hack squat
- 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.
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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: squat pattern, 2400 ms rep trace, engine-derived.
