Influence of outdoor running surface type on loading rate and lower-limb kinematics

Background Running surface characteristics may influence loading rate and lower-limb biomechanics during running. However, evidence regarding the effects of outdoor running surfaces remains limited. Therefore, this study investigated the effects of different outdoor running surfaces on vertical average loading rate (VALR) and lower-limb sagittal-plane kinematics during running. Methods Twenty-two healthy male recreational runners completed running trials on three outdoor surfaces: concrete, rubber track, and artificial turf. VALR was measured using Loadsol in-shoe sensors, and lower-limb kinematics were assessed using wearable inertial sensors (Xsens). Participants ran at a self-selected speed. Repeated measures ANOVA examined differences in VALR across surfaces, while statistical parametric mapping assessed continuous sagittal-plane kinematics throughout the gait cycle. Results Surface type significantly affected VALR, F(1.31, 27.43) = 10.86, p = .001, ηp² = 0.34. VALR was greatest on concrete (67.95 ± 19.72 BW/s), followed by rubber track (60.77 ± 18.23 BW/s), and lowest on artificial turf (58.00 ± 17.15 BW/s). Post hoc analysis showed greater VALR on concrete than rubber track and artificial turf, and greater VALR on rubber track than artificial turf. A significant surface effect was identified for hip kinematics, with greater hip angle on concrete than on the rubber track between 45.6% and 60.3% of the gait cycle (cluster p = .004). No significant surface effects were identified for knee or ankle kinematics. Conclusions Among the three tested outdoor surface types, the concrete condition was associated with a higher VALR than the rubber track and artificial turf conditions. Hip kinematics differed between concrete and the rubber track during swing, whereas knee and ankle kinematics did not differ between surfaces. Given that a large proportion of recreational running in Saudi Arabia is performed on concrete pavements, these findings may provide surface-specific loading data relevant to runners in this setting.