Back Squats

The back squat holds the bar behind the neck on the shoulders. High bar placement is the "Back Squat"; low bar placement is the "Power Back Squat" — now its own structured record, Low-Bar Squat, since it shifts enough emphasis toward the posterior chain to warrant separate muscle attribution rather than being folded into this one. This module (and its spine record ex.back-squat) covers the high-bar version specifically. The full technique and evidence lesson is Squats.

Muscles. The knees and hips extend together. The three vasti extend the knee; gluteus maximus and adductor magnus extend the hip and work hardest near the bottom. Rectus femoris and the shorter adductors (longus, brevis) assist. In Kubo et al. (2019), 10 weeks of squat training grew the vasti, the adductors and gluteus maximus, while rectus femoris and the hamstrings did not grow, which is why rectus femoris is secondary here.

Depth and knee load. Squat as deep as you can control with a braced trunk (the old "stop at parallel, full range not recommended" rule is outdated — see Squat Depth and Knee Safety (Deep Squats Are Not Inherently Dangerous)). Hartmann, Wirth & Klusemann (2013) found kneecap compressive stress peaks around 90° of knee flexion and falls with deeper flexion, and that deep squats do not raise injury risk to passive tissues in healthy knees when technique and loading are progressed sensibly.

Technique. Feet about shoulder width. Keep the spine in its natural curves, braced from top to bottom. Stand fully tall at the top without snapping the knees back. Understand the femur-vs-torso length, knee-toe, hip-knee and knee-foot relationships: a long femur relative to the torso means more forward lean, which shifts emphasis toward the glutes and erector spinae. A weightlifting belt has traditionally been recommended for heavy squats; see Weightlifting Belt — Proper Use & Safety Concerns for the trade-offs.

• Primary muscles: vastus lateralis, vastus medialis, vastus intermedius, gluteus maximus, adductor magnus.
• Secondary muscles: rectus femoris, adductor longus, adductor brevis.
• High-bar = Back Squat; low-bar = Power Back Squat.
• Kneecap compressive stress peaks around 90° of knee flexion and falls with deeper flexion; deep squats don't raise passive-tissue injury risk in healthy knees (Hartmann et al. 2013).
• Squat training grew the vasti, adductors and gluteus maximus, not rectus femoris or the hamstrings (Kubo et al. 2019).