Why Biomechanics Matter

Whether you're chasing PRs or just trying to run pain-free, understanding your biomechanics is critical. Inefficient form doesn’t just slow you down — it sets you up for injury. This post explores two primary planes of motion during running: the sagittal plane (side view) and the frontal plane (front/back view), along with tools and cues to help you improve.

Sagittal Plane: Efficiency in Motion

The sagittal plane reveals how your body moves forward. Through video analysis from the side, you can evaluate key elements such as:

• Trunk Angle: A forward lean of 5–10° helps engage glutes and quads together for better propulsion and shock absorption.
• Hip & Knee Flexion: Look for 20–25° of flexion at impact for proper loading and shock absorption.
• Foot Strike: Heel or forefoot strikes are both viable, but don’t try to switch without professional guidance.
• Overstriding: Foot landing too far ahead acts like a brake and increases injury risk.
• Cadence: 160–180 steps per minute is the sweet spot to reduce impact.
• Ankle Dorsiflexion: At least 20° during stance for smooth shock absorption.

Frontal Plane: Controlling Lateral Movement

The frontal plane is where many hidden inefficiencies and injury risks lie. Filming from the front or back can reveal:

• Trunk Sway: Keep lateral sway under 5° to prevent spinal stress and energy leaks.
• Pelvic Drop: Watch for more than 5° drop opposite the stance leg — it indicates poor hip stability.
• Knee Valgus: Knees caving in increases ACL and patellofemoral risks, especially in female runners.
• Knee Varus: Less common, but excessive bowing outward can strain joints unevenly.
• Crossover Gait: Feet crossing midline while running may reflect hip flexor tightness or core instability.

How to Use Video Analysis

Use your phone or motion capture app to record yourself running from both side and front views. Then:

• Draw vertical and horizontal reference lines to track sway and lean angles.
• Use joint angle tools to measure trunk flexion, hip and knee range, and ankle dorsiflexion.
• Use graphing features to track these metrics frame-by-frame.

Start Small: Focus on One Fix at a Time

It’s tempting to correct every form fault at once, but small adjustments are more effective. Pick one cue — like a trunk lean or pelvic alignment — and work on it consistently over several runs.

What to Read Next

Dive deeper into each topic with our detailed breakdowns:

• Trunk Position
• Hip & Knee Control
• Foot Strike Patterns
• Avoiding Overstriding
• Cadence
• Frontal Plane Mechanics