Running Velocity Does Not Influence Lower Limb Mechanical Asymmetry.

Area of Science:

• Biomechanics
• Sports Science
• Human Movement Analysis

Background:

• Running asymmetry can influence performance and injury risk.
• Understanding how running velocity affects asymmetry is crucial for training and rehabilitation.
• Previous research has yielded mixed results on the impact of speed on running mechanics.

Purpose of the Study:

• To investigate the effect of varying running velocities on the magnitude and range of asymmetry in running kinetics and kinematics.
• To determine if changes in treadmill belt velocity influence asymmetry scores in well-trained runners.

Main Methods:

• Nine well-trained, un-injured distance runners completed treadmill running at seven velocities (10-25 km/h).
• Continuous measurement of spatio-temporal, horizontal force, and spring-mass characteristics at 1,000 Hz.
• Asymmetry was quantified using the 'symmetry angle' (SA) formula, analyzing 10 consecutive steps.

Main Results:

• Spatio-temporal variables (contact time, aerial time, step length/frequency) showed low asymmetry (mean SA < 2%).
• Loading rate and spring-mass characteristics (vertical force, displacement, stiffness) exhibited higher mean SA values.
• No significant influence of running velocity on asymmetry scores was found for most mechanical variables, except braking impulse (p=0.005).

Conclusions:

• Treadmill running velocity adjustments (10-25 km/h) did not substantially alter group mean or range of asymmetry scores.
• The magnitude of asymmetry is primarily dependent on the specific biomechanical variable being measured.
• Significant inter-individual variability in asymmetry underscores the need for personalized biomechanical assessments.