Strength training can improve running economy (RE) and performance in distance runners. This study investigated the effect of potential adaptations stemming from strength training on RE using simulation. Muscle-tendon unit (MTU) properties (muscle strength and mass, pennation angle, tendon stiffness, fibre composition) of muscle groups were altered within muscle-driven simulations of running at 4.5 and 6.5 m·s-1. Outputs from the muscle-driven simulations were input to an energetics model to determine whole-body metabolic power. Alterations to MTU properties resulted in variable changes (range = 1.4% decrement – 8.9% improvement in RE) to whole-body metabolic power and RE. The findings highlight potential targets for strength training programs aiming to improve RE in distance runners