The Relationships between Age and Running Biomechanics.

Unlabelled: Running has high injury rates, especially among older runners. Most aging literature compares young with old runners without accounting for the progression of biomechanics throughout the lifespan. We used age as a continuous variable to investigate the continuum of age-related gait adaptations in running along with determining the chronology and rate of these adaptations.

Purpose: This study aimed to identify the relations among age and selected running biomechanics throughout the range of 18-60 yr.

Methods: Experienced (n = 110) healthy runners (male, 54%) provided informed consent and ran at their training pace while motion and force data were captured. Kinematics, ground reaction forces (GRF), and lower limb joint torques and powers were correlated with age using Pearson product-moment correlations and linear regression.

Results: Running velocity was inversely related to age (r = -0.27, P = 0.005) because of decreased stride length (r = -0.25, P = 0.008) but not rate. Peak vertical GRF (r = -0.23, P = 0.016) and peak horizontal propulsive GRF decreased with age (r = -0.38, P < 0.0001). Peak ankle torque (r = -0.32, P = 0.0007) and peak negative (r = 0.34, P = 0.0003) and positive (r = -0.37, P < 0.0001) ankle power decreased with age. Age-based regression equations and per-year reductions in all variables significantly related to age are reported.

Conclusions: Data support previous work showing lower GRF, stride length, and velocity in old runners. Results are novel in showing the rate of decline in running biomechanics on a per-year basis and that mechanical reductions at the ankle but not at the hip or knee were correlated with age, confirming a previous observation of biomechanical plasticity with age showing reduced ankle but not hip function in gait.