Back Squat
The back squat is a squat pattern defined by the barbell resting across the upper back. It is one of the most widely used compound movements in strength training, and one of the three powerlifting competition lifts.
Execution
- Position the bar across the upper traps (high bar) or rear delts (low bar)
- Stance slightly wider than shoulders, toes turned out 15–30 degrees
- Inhale and brace with a Valsalva maneuver, tightening the core
- Flex hips and knees together, tracking knees over the toes
- Drive up out of the bottom by extending the hips
Common Faults
- Valgus collapse — knees cave inward; typically from weak glute medius and abductors
- Excessive forward lean — usually limited ankle mobility or insufficient core bracing
- Insufficient depth — tight hip flexors or a miscalibrated sense of depth
What the EMG Data Shows
Activation increases non-linearly with load. The quadriceps (vastus medialis, lateralis, rectus femoris) are consistently the dominant prime movers. Gluteus maximus activation increases markedly only at very high loads (90–100% 1RM), suggesting the glutes are more load-sensitive than depth-sensitive in the back squat. Erector spinae acts as a stabilizer throughout, with activation in the 40–46% MVC range at 80–100% 1RM.
The sticking point falls in the bottom third of the ascent, where the hip moment arm peaks despite a reduction in ground reaction force — this is primarily a hip extensor failure point, not a knee extensor failure point.
Variations
| Variation | Key difference | Best for |
|---|---|---|
| High bar | More upright torso, quad-dominant | Bodybuilding, weightlifting accessory |
| Low bar | Greater lean, hips and legs share load | Powerlifting |
| Box squat | Fixed depth reference | Beginners, fear management |
For system-specific training applications, see each system's lens entry.