Running on unpaved trails is commonly perceived to reduce impact loading and injury risk, yet biomechanical evidence remains limited across age groups. We investigated the effects of paved versus unpaved surfaces on running biomechanics and surface-related injury risk perceptions in Master and young adult runners. Sixty participants (30 Master, 30 young adult) completed 5 km runs on both surfaces while wearing triaxial tibial accelerometers. We compared average cadence, peak resultant and axial tibial acceleration (TA), and cumulative resultant and axial TA using ANCOVA, controlling for running speed. Peak resultant TA was higher on unpaved than paved surfaces (p = .014), whereas cadence, peak axial TA, and cumulative axial and resultant TA did not differ between surfaces (p > .05). Master runners exhibited higher cadence and lower peak resultant TA than young adults (p < .05), while cumulative resultant TA did not differ by age (p > .05). Nearly half the participants (48.3%) perceived that running on unpaved trails reduces injury risk. Overall, unpaved trails produced higher peak TA without changing cumulative TA. Age-group differences in cadence were accompanied by lower peak resultant TA for Master runners, suggesting an age-related shift towards reduced per-step impact magnitude.
Keywords: Ageing; impact loading; injury prevention; surface stiffness; tibial shock.