Lecture on Running Biomechanics and Ground Reaction Forces

Key Figures and Examples

• David Oliver: World champion and gold medalist in 110-meter hurdles
  • Running speed: 10.2 m/s
  • Runs on SMU high-speed Force treadmill
  • Applies forces up to five times body weight in less than 100 milliseconds per leg
• Ryan Hall: Fastest American marathoner
  • Running speed: 5.7 m/s (2-hour and 3-minute marathon pace)
  • Different force pattern: Lower amplitude, longer duration
  • Impacts ground 25,000 times during marathon with peak force of three times body weight

Importance of Running Ground Reaction Forces

• Fundamental physical and biological significance in running

Underlying Principles

• Newton’s Laws of Motion: Relate force to the motion of a runner
• Two Mass System Model:
  • Mass 1: Lower contacting limb
  • Mass 2: Rest of the body

Force and Motion Dynamics

• Impulsive Force: Results from the vertical collision of the lower limb with the running surface
  • Magnitude and timing depend on vertical acceleration of the ankle
• Total Vertical Ground Reaction Force:
  • Sum of forces from lower limb collision and vertical motion of the rest of the body
  • Determined by three motion parameters:
    • Contact time
    • Aerial time
    • Lower limb acceleration

Model Predictions and Applications

• Accurately predicted forces across running speeds from 3 to 11 m/s
• Tested on 42 men and women with different footstrike mechanics
• Applications:
  • Gait analysis
  • Robotics
  • Prosthetics
  • Orthotics
  • Shoewear design

Research Reference

• Research details published in the Journal of Experimental Biology
• Presenter: Ken Clark