Inter-joint coordination patterns differ between younger and older runners

Older runners are at greater risk of certain running-related injuries. Previous work demonstrated that aging influences running biomechanics, and suggest a compensatory relation between changes in the proximal and distal joints. Previous comparisons of interjoint coordination strategies between young and older runners could potentially have missed relevant differences by averaging coordination measures across time. Objective: To compare coordination strategies between male runners under the age of 30 to those over the age of 60. Methods: Twelve young (22 ± 3 yrs, 1.80 ± 0.07 m, 78.0 ± 12.1 kg) and 12 older (63 ± 3 yrs, 1.78 ± 0.06 m, 73.2 ± 15.8 kg) male runners ran at 3.35 m/s on an instrumented treadmill. Ankle frontal plane, tibial transverse plane, knee sagittal plane, and hip frontal plane motion were measured. Inter-joint coordination was calculated using a modified vector coding technique. Coordination patterns and variability time series were compared between groups throughout stance using ANOVA for circular data. Results: At the ankle, older runners use in-phase propulsion (inversion, tibia external rotation) pattern following midstance (46–47% stance) while young runners are still in an in-phase collapse pattern (eversion, tibia external rotation). In coordination of the knee and hip, older runners maintained an in-phase collapse pattern (knee flexion, hip adduction) approaching midstance (35–37% stance), while younger runners use an out of phase strategy (knee extension, hip adduction). In coordination of the ankle and hip in the frontal plane, older runners again maintained an in phase collapse pattern up to midstance (34–39% stance), while younger runners used an out of phase strategy (ankle inversion, hip adduction). Variability was similar between age groups. Conclusion: Older runners appear to display altered coordination patterns during mid-stance, which may indicate protective biomechanical adaptations. These changes may also have implications for performance in older runners.