🏃 Iliotibial Band Friction Syndrome Simulator

Normal Iliotibial Band Glide

The IT band slides smoothly over the lateral femoral epicondyle.

• ~45 cm: IT Band Length (Runs from hip to tibia)
• ~30°: Peak Contact Angle (Mid-flexion crossing point)
• Low: Friction Coefficient (Bursa cushions the glide)
• 160–180: Typical Cadence (Steps per minute running)

Anatomy of the IT band

A thick fascial band runs from the hip to the tibia.

The impingement zone

Near 30° flexion the band crosses the lateral epicondyle.

Repetitive Knee Flexion Through the Danger Zone

Running repeatedly drives the knee through the 20–30° zone.

• ~2,500: Strides per 5K Run (Each one flexes the knee)
• 2: Crossings per Stride (Flexion and extension pass)
• Higher = More: Cadence Effect (Faster steps, more crossings)
• Elevated: Downhill Risk (Extra knee flexion time)

Gait cycle mechanics

Each stride flexes and extends the knee past the friction point.

Cumulative loading

Thousands of crossings build up over a single training run.

Friction Zone Tissue Irritation

Repeated compression inflames tissue beneath the tight IT band.

• Mild–Mod: Bursal Swelling (Fluid builds under the band)
• Elevated: Local Temperature (Inflammation raises tissue heat)
• Lowered: Irritation Threshold (Tissue tolerates less friction)
• 24–72 h: Recovery Window (Between irritating sessions)

Compression injury

Tight bands press harder against the epicondyle each pass.

Bursitis development

The underlying bursa swells and grows tender to touch.

Ober Test — Positive for IT Band Tightness

A tight IT band restricts hip adduction during the Ober test.

• 10–15°: Normal Adduction (Leg drops below horizontal)
• <5°: Positive Test Angle (Leg stays elevated, restricted)
• Side-Lying: Test Position (Hip extended, knee flexed)
• Moderate: Clinical Sensitivity (Useful with other findings)

Performing the test

The hip is extended and adducted with the knee bent.

Positive sign

The leg fails to drop when the band is tight.

Lateral Knee Pain During Impingement

Inflammation now triggers sharp pain within the impingement zone.

• ~30° flexion: Pain Onset (Consistent trigger angle)
• 6–9 / 10: Pain Score (Sharp, localized lateral pain)
• Distance Running: Common Sport (Cycling also implicated)
• 2–6 weeks: Typical Rest Needed (For full symptom resolution)

Pain pattern

Sharp lateral pain appears at a consistent flexion angle.

Functional impact

Runners often must stop mid-run once pain intensifies.