Exploring Neuromuscular and Biomechanical Factors Associated with Improvements in Running Economy Following Plyometric Training in Male Master Endurance Runners

PURPOSE: While running economy can be improved following plyometric training, the factors associated with running economy improvements remain unclear, particularly in master endurance runners. This study aimed to identify neuromuscular and biomechanical factors associated with running economy improvements following plyometric training in male master endurance runners. METHODS: Thirty-five male master endurance runners performed plyometric training twice weekly for 10 weeks. Isokinetic knee extension/flexion torques, isometric ankle dorsiflexion/plantarflexion torques, and countermovement, drop, and rebound jump performance were measured pre- and post-intervention. Running biomechanical variables and running economy at 80% velocity of V̇O2max were also recorded during a 30-minute run. To assess measurement reliability, a subset of 21 runners repeated the same protocol over ≥3 months before the intervention. A linear mixed-effects model was applied, with changes in running economy as the dependent variable and significantly associated factors (P<0.05) as predictors, and running volume as a covariate. RESULTS: Running economy was improved following plyometric training (-3.9%, P=0.002), with 77.1% of runners exceeding the typical error (1.45%) derived from the repeatability dataset. Changes in running economy were significantly associated with those in drop/rebound jump height and step frequency (standardized β=-0.569 to 0.490, P=0.008-0.035), explaining 51.4% of the variance in running economy improvement (P=0.005). A significant interaction between rebound-jump height and step frequency was found (P=0.048), indicating that runners who increased rebound-jump height while reducing step frequency showed greater running economy improvement. No such associations were observed in the repeatability dataset, suggesting that the observed relationships are unlikely to be explained by measurement variability. CONCLUSIONS: Enhanced reactive jump ability combined with a reduced step frequency following plyometric training may underlie running economy improvements in male master endurance runners.