Is squatting a safe exercise for individuals with knee health concerns?

Is Squatting Safe for Individuals with Knee Health Concerns?

Yes, squatting is safe and recommended for individuals with knee health concerns, including those with knee osteoarthritis, provided proper technique is maintained and the exercise is appropriately progressed. The evidence strongly supports squatting as a beneficial strengthening exercise rather than a harmful activity.

Evidence Supporting Squatting Safety

Quadriceps Strengthening Benefits

• Quadriceps strengthening exercises, which include squatting movements, are specifically recommended for patients with symptomatic knee osteoarthritis with statistically significant and possibly clinically important effects on both pain and function 1.
• The American Academy of Orthopaedic Surgeons provides Grade B recommendation (Level II evidence) for quadriceps strengthening in knee OA patients 1.

Strength Training Recommendations

• Progressive strength training involving major muscle groups at moderate to vigorous intensity (60-80% of one repetition maximum) for 8-12 repetitions at least 2 days per week is recommended for people with knee OA 1.
• Both specific quadriceps strengthening and lower limb strength training reduce pain effectively (effect sizes 0.29-0.53) and improve physical function (effect sizes 0.24-0.58) 1.

Deep Squatting Specifically

Biomechanical Safety

• Deep squats do not contribute to increased risk of injury to passive knee tissues when performed with proper technique 2.
• A comprehensive 2024 scoping review found that 14 out of 15 studies showed no negative impact of deep squats on knee joint health; only one case study associated deep squats with injury risk 3.
• The highest retropatellar compressive forces occur at 90° of knee flexion, but with deeper flexion, the wrapping effect and enlarged contact surface area actually reduce compressive stresses 2.

Protective Effects

• Deep squats present an effective training exercise for protection against injuries and strengthening of the lower extremity when technique is learned accurately under expert supervision with progressive training loads 2.
• Menisci, cartilage, ligaments, and bones undergo anabolic metabolic processes and functional structural adaptations in response to increased activity from squatting 2.

Important Caveats and Technique Considerations

Stance and Form Modifications

• Stance width and foot placement angles should be chosen according to targeted joint moments 4.
• Special care should be taken in extreme positions (narrow stance with 42° foot angle or wide stance with 0° foot angle) where large knee and hip joint moments occur 4.
• Restricting anterior knee displacement (the outdated "knees shouldn't pass toes" rule) increases biomechanical stress on the lumbar spine and hip and should not be practiced for healthy trained individuals 5.

Progression and Supervision

• Initial instruction under expert supervision is required, with at least 12 directly supervised sessions showing superior outcomes compared to fewer sessions (effect size 0.46 vs 0.28 for pain, p=0.03) 1.
• Progressive loading over time is essential, with most effective strength training studies using dynamic exercises with progression 1.

What to Avoid

Risky Activity Combinations

• Combined kneeling, squatting, and bending activities with heavy loads have strong evidence for increasing knee OA risk 6.
• Notably, when kneeling and squatting are examined individually in isolation, they show no increased risk 6.
• Heavy physical demands in occupational settings with repetitive combined movements increase knee OA risk 6.

Comparison to Partial Squats

• Half and quarter squats with supra-maximal loads (attempting to compensate for reduced range of motion) will favor degenerative changes in knee and spinal joints long-term compared to properly loaded deep squats 2.

Clinical Algorithm for Implementation

For patients with knee OA or concerns:

1. Begin with low-impact aerobic exercises (walking, cycling) as Grade A recommendation 1
2. Add quadriceps strengthening including squatting movements with proper supervision 1
3. Progress to 60-80% of one repetition maximum for 8-12 repetitions, at least 2 days per week 1
4. Allow natural anterior knee displacement during the movement 5
5. Choose appropriate stance width and foot angles based on individual biomechanics 4
6. Progress depth as tolerated, recognizing that deeper squats with appropriate load are safer than partial squats with excessive load 2

The key distinction: Squatting as a controlled, progressive strengthening exercise is beneficial and protective, while prolonged occupational squatting combined with kneeling and bending under heavy loads increases OA risk 6.