Knee Movement During Squats: Causes, Concerns, and Correction Strategies

Why do my knees move when I squat?

Knee movement during a squat, often seen as the knees caving inward (valgus collapse) or bowing outward (varus), is a common biomechanical deviation stemming from a complex interplay of muscular imbalances, mobility restrictions, and suboptimal motor control, which can compromise joint integrity and performance.

Understanding "Knee Movement" During Squats

When discussing "knee movement" during a squat, we are typically referring to deviations from the ideal path where the knees track directly over the mid-foot. The most common and concerning deviation is knee valgus, where the knees collapse inward towards each other. Less commonly, but still important to recognize, is knee varus, where the knees bow excessively outward. Both indicate underlying issues that warrant attention to prevent injury and optimize squat mechanics.

The Biomechanics of a Proper Squat

A well-executed squat involves the hips, knees, and ankles flexing simultaneously, with the torso maintaining a relatively upright position. Crucially, the knees should track in alignment with the feet, typically over the second or third toe, throughout the entire range of motion. This alignment ensures optimal force distribution across the knee joint and efficient recruitment of the primary movers: the quadriceps, hamstrings, and glutes.

Common Causes of Knee Valgus (Knees Caving In)

Knee valgus is a multifaceted issue, often resulting from a combination of factors along the kinetic chain.

• Weak Gluteal Muscles (Gluteus Medius & Maximus):

  • The gluteus medius is a primary hip abductor and external rotator, crucial for stabilizing the pelvis and preventing the femur (thigh bone) from internally rotating and adducting (moving inward).
  • The gluteus maximus is a powerful hip extensor and external rotator. If it's weak or underactive, the hip loses its ability to externally rotate, allowing the knees to collapse inward.
  • When these muscles are weak or inhibited, the adductor muscles (inner thigh) can become dominant, pulling the knees inward.

• Adductor Dominance or Tightness:

  • The adductor muscles (e.g., adductor longus, magnus, brevis) are powerful hip adductors. If they are overly tight or dominant relative to the gluteal muscles, they can pull the knees inward, especially during the eccentric (lowering) phase of the squat.

• Limited Ankle Dorsiflexion:

  • Dorsiflexion is the ability to bring your shin forward over your foot. If your ankle mobility is restricted (e.g., tight calves, stiff ankle joint), your body will seek compensation higher up the kinetic chain.
  • To achieve squat depth with limited ankle dorsiflexion, the hips may be forced to tuck under (posterior pelvic tilt), or the knees may collapse inward to allow the torso to remain upright and prevent falling backward.

• Foot Pronation/Arch Collapse:

  • Excessive pronation (flattening of the arch) of the foot can cause internal rotation of the tibia (shin bone) and femur, leading to knee valgus. The foundation of your squat starts from the ground up.

• Poor Motor Control/Neuromuscular Coordination:

  • Sometimes, even with adequate strength and mobility, the brain's ability to coordinate muscle activation for proper squat mechanics is lacking. This can be due to a lack of practice, improper cueing, or a learned movement pattern.

• Inappropriate Stance Width or Foot Angle:

  • Squatting with a stance that is too narrow or too wide, or with feet pointed excessively straight or outward, can place the hips and knees in disadvantageous positions, promoting valgus collapse.

• Insufficient Hip Mobility (Internal Rotation Bias):

  • While external rotation is desired, if hip internal rotation is restricted or there's an imbalance in hip capsule mobility, it can limit the ability to maintain external rotation during the squat, leading to compensatory knee valgus.

Less Common: Knee Varus (Knees Bowing Out)

Knee varus, or the knees bowing excessively outward, is less common but can occur. It might indicate:

• Overactive or Dominant Hip Abductors: While glute strength is good, an overreliance on abductors without proper quadriceps or adductor engagement can cause the knees to push out excessively.
• Attempting to "Push Knees Out" Too Aggressively: Sometimes, an overcorrection to prevent valgus can lead to excessive varus.
• Anatomical Variations: In rare cases, structural variations in the femur or tibia can contribute.

Why is Knee Movement a Concern?

Deviations like knee valgus are not just aesthetic issues; they significantly increase the risk of injury and reduce the efficiency of the squat:

• Increased Stress on Ligaments: Puts undue strain on the medial collateral ligament (MCL) of the knee, which resists valgus forces. Chronic stress can lead to laxity or tears.
• Patellofemoral Pain Syndrome: Improper tracking of the kneecap (patella) due to valgus can cause pain around or behind the kneecap.
• Meniscus Damage: Uneven loading across the knee joint can increase stress on the meniscus.
• Reduced Force Transfer: Energy is dissipated through inefficient movement patterns, compromising the amount of weight that can be lifted and the effectiveness of the exercise for muscle development.
• Long-Term Joint Degeneration: Chronic improper mechanics can accelerate wear and tear on the knee joint.

Strategies to Correct Knee Movement

Addressing knee movement requires a systematic approach focusing on mobility, strength, and motor control.

• Assess and Address Mobility Limitations:

  • Ankle Dorsiflexion: Perform ankle mobility drills (e.g., wall ankle mobilizations, calf stretches).
  • Hip Mobility: Incorporate hip internal and external rotation drills, hip flexor stretches, and glute stretches.

• Strengthen Key Stabilizer Muscles:

  • Gluteus Medius: Exercises like banded lateral walks, clam shells, and side-lying leg raises.
  • Gluteus Maximus: Glute bridges, hip thrusts, and sumo deadlifts.
  • Adductors: While often tight, strengthening them through exercises like Copenhagen planks or sumo squats can improve their coordinated action with the glutes.
  • Core Strength: A strong core provides a stable base for the hips and lower extremities.

• Improve Motor Control and Technique:

  • Squat with External Cues: Use a resistance band around the knees (just below or above) to provide tactile feedback and encourage pushing the knees out against the band.
  • Box Squats: Help control depth and reinforce proper hip drive.
  • Tempo Squats: Slowing down the eccentric phase allows for better control and awareness of knee position.
  • Goblet Squats: The anterior load helps maintain an upright torso and can make it easier to feel proper knee tracking.
  • Focus on the "Knees Out" Cue: Consciously think about driving the knees outward, in line with the feet, throughout the movement.

• Adjust Stance and Foot Placement:

  • Experiment with slightly wider or narrower stances, and varying degrees of foot flare, to find the most comfortable and stable position that allows for proper knee tracking. Generally, a stance slightly wider than shoulder-width with a moderate foot flare (15-30 degrees) works well for most.

• Consider Footwear and Orthotics:

  • Flat-soled, stable shoes are generally preferred for squatting. If pronation is a significant issue, consulting with a podiatrist about orthotics might be beneficial.

• Start with Bodyweight and Progress Gradually:

  • Master the movement pattern with bodyweight before adding external load. Gradually increase weight only when proper form can be maintained.

When to Seek Professional Guidance

If you consistently experience knee movement despite implementing corrective strategies, or if you experience pain during squats, it's advisable to consult with a qualified professional. A physical therapist or experienced strength and conditioning coach can perform a thorough movement assessment, identify specific limitations, and prescribe a tailored corrective exercise program.

Conclusion

Knee movement during squats is a common but correctable issue. By understanding the underlying biomechanical principles and identifying the specific weaknesses or restrictions contributing to the deviation, you can implement targeted strategies to improve your squat mechanics. Prioritizing proper form over heavy weight will not only safeguard your knee health but also unlock greater strength and performance potential in the long run.