Does Changing Step Width Alter Lower Extremity Biomechanics During Running?

A large percentage of runners incur a running related injury, with injury occurring most frequently at the knee. Runners with the most common overuse knee injuries have associated biomechanics that differ from healthy runners. Altering step width while running may influence those associated biomechanics. The purpose of this study was to determine the biomechanical response of lower extremity joints in healthy runners to increasing and decreasing step width during running. A preferred step width condition was collected first, followed in randomized order by a narrow step width condition and a wide step width condition. Step width was decreased to 0% of participant’s leg length during the narrow condition, and increased to 20% of participant’s leg length during the wide condition. Step width, peak lower extremity angles, peak lower extremity moments, and knee abduction impulse were recorded. Step width changed successfully in all conditions, and was similar between genders with no interaction effect. Peak hip adduction angle decreased as step width increased from narrowest to widest, and was larger in women compared to men without an interaction effect. Peak hip internal rotation angle remained similar among step width conditions and genders, with no interaction effect. Peak knee internal rotation angle increased when step width increased from narrowest to widest, and was larger in women than men with no interaction effect. Peak knee abduction moment decreased when step width increased from narrowest to widest, and was larger in men than women with no interaction effect. Knee abduction angular impulse decreased when step width increased from narrowest to widest, and was larger in men than women, with no interaction effect. Peak rearfoot eversion angle decreased when step width increased from narrowest to widest and was larger in women, with no interaction effect. Peak rearfoot inversion moment had a significant interaction effect, and decreased in male runners more than in female runners as step width increased from narrowest to widest. Findings suggest frontal plane biomechanics of healthy runners are influenced by step width.