Tibial loading and damage accumulation in recreational and competitive male runners during a demanding 10 km run

Abstract

Tibial stress injuries are problematic among runners. The loading magnitude is the most important mechanical contributor to bone damage accumulation, but loading quantity is also important, and faster runners require fewer loading cycles to complete a given distance than slower runners. This study estimated tibial loading and damage accumulation throughout a demanding 10‐km run in recreational (RR) and competitive runners (CR). Male runners reporting a 10‐km season‐best run slower than 47:30 min (RR) or faster than 37:30 min (CR) completed a 10‐km treadmill running protocol at 105% of their season's best time. Tibial loading was estimated from bending moments at the distal 1/3rd of the tibia by ensuring static equilibrium at each 1% of stance. Peak loading was obtained, and cumulative damage per kilometer was estimated using a tissue‐dependent weighting factor. Peak tibial loading and damage accumulation per kilometer significantly decreased throughout the run, by 5% and 4%, respectively. Peak loading was significantly higher (31%) in CR than RR, and there was an indication (p = 0.058 and large effect size) of a greater rate of damage accumulation in CR than RR. Tibial loading per step and the rate of accumulation per kilometer decreased throughout a demanding 10‐km run suggesting that changes in running mechanics as a result of prolonged running may not be a primary mechanism for stress injury development. Competitive runners experience greater peak tibial loading and possibly greater cumulative tibial damage when they complete 10 km faster than recreational runners.