Variables during swing associated with decreased impact peak and loading rate in running
Anne Schmitz1, Michael B Pohl2, Kaitlin Woods1
1Department of Rehabilitation Sciences, University of Kentucky, Lexington, KY, USA.
Journal of Biomechanics
|November 9, 2013
Summary
Running impact forces can cause overuse injuries. Increased hip flexor activity during swing may reduce impact loading rates and forces by altering leg swing kinematics and decreasing landing velocity.
Area of Science:
- Biomechanics
- Sports Medicine
- Orthopedics
Background:
- Running generates significant impact forces and loading rates.
- These forces are implicated in the development of overuse injuries.
- Understanding biomechanical predictors of impact loads is crucial for injury prevention.
Purpose of the Study:
- Identify key variables predicting impact peak and loading rate during running.
- Investigate the effect of modulating hip and knee muscle activity on these impact variables.
Main Methods:
- Instrumented gait analysis of 48 healthy runners at 3.3 m/s.
- Stepwise multiple linear regression to identify predictors.
- Forward dynamics simulation with a musculoskeletal model to assess muscle activity modulation.
Main Results:
- Smaller impact peaks correlated with greater foot downward acceleration, higher foot position, and decreased shank downward velocity at mid-swing.
- Lower loading rates were associated with a higher thigh position at mid-swing.
- Increased hip flexor activity during swing altered mid-swing kinematics.
Conclusions:
- Increased hip flexor activity during the swing phase may offer an alternative to forefoot striking for reducing impact loads.
- Altering swing phase kinematics can decrease leg velocity at landing.
- Reduced landing velocity decreases downward momentum, thereby lowering impact forces.
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