Effect of age on ankle biomechanics and tibial compression during stair descent

Stress fracture is a concern among older adults, as age-related decrements in ankle neuromuscular function may impair their ability to attenuate tibial compressive forces experienced during daily locomotor tasks, such as stair descent. Yet, it is unknown if older adults exhibit greater tibial compression than their younger counterparts when descending stairs. Do older adults exhibit differences in ankle biomechanics that alter their tibial compression during stair descent compared to young adults, and is there a relation between tibial compression and specific changes in ankle biomechanics? Thirteen young (18–25 years) and 13 older (> 65 years) adults had ankle joint biomechanics and tibial compression quantified during a stair descent. Discrete ankle biomechanics (peak joint angle and moment, and joint stiffness) and tibial compression (maximum and impulse) measures were submitted to an independent t-test, while ankle joint angle and moment, and tibial compression waveforms were submitted to an independent statistical parametric mapping t-test to determine group differences. Pearson correlation coefficients (r) determined the relation between discrete ankle biomechanics and tibial compression measures for all participants, and each group. Older adults exhibited smaller maximum tibial compression (p = 0.004) from decreases in peak ankle joint angle and moment between 17 % and 34 % (p = 0.035), and 20–31 % of stance (p