Knee Safety in the Squat

The knee joint ROM is 90 degrees (a hinge joint). From a standing position to a knee-bend at 90 degrees, the knee joint experiences 8 times more pressure. Years of leg workouts and overuse can produce "Patellar Tracking Dysfunction (PTD)," meaning the patella does not "track" straight when the knee is flexed or extended (lateral tracking). The function of the patella is to increase force area and improve the mechanics of the knee joint. The vastus medialis becomes strongest during the last 15 degrees of a knee extension movement.

Safe squat technique: a. Do not lock out the knee. b. Ensure proper spinal alignment is observed (muscles in semi-isometric contraction). c. Squat to a position close to parallel to the floor. d. Keep feet at about shoulder width apart. e. Understand the "femur length vs. torso length" relationship. f. Understand the "knee–toe" relationship. g. Understand the "hip–knee" relationship. h. Understand "knee–foot" placement. i. Understand "stance width" of feet. j. Not all people can squat to a parallel position. k. Check position of the bar.

• Knee joint ROM is 90° (hinge joint).
• Knee pressure increases ~8× going from standing to a 90° knee bend.
• Vastus medialis is strongest during the last 15° of knee extension.
• Patellar Tracking Dysfunction (PTD) = patella tracks laterally rather than straight.
• Do not lock out; keep spine aligned (semi-isometric); squat to near-parallel; feet ~shoulder width.

• knee-toe-relationship — knee/toe alignment rule.
• deep-squats-not-recommended — full-ROM exception for the squat.
• deep-knee-bend — the contraindicated ballistic/bouncing version of a deep bend.
• bar-placement — high/low/front bar position.
• locking-out — locking-out cautions.
• spine-positioning — "S"-shape spine in semi-isometric contraction.
• knee-joint-rom — knee ROM (90°).
• quadriceps — vastus medialis tracking the patella.
• femur-torso-length-squat — proportions affecting squat depth/lean.
• exercise-selections-by-training-level — the Sissy Squat (listed there as an advanced quad exercise) carries a similar knee-loading caution: high patellofemoral stress that's fine for healthy knees but should be avoided or modified for patellar tendinopathy, recent ACL reconstruction, or PFPS.
• knee-wraps — a squat-support accessory with its own patellar-tracking cautions.