Strength Training Improves Running Economy Durability and Fatigued High-Intensity Performance in Well-Trained Male Runners: A Randomized Control Trial

ABSTRACT Introduction Strength training improves running economy (RE) in a nonfatigued state and performance after prolonged exercise at moderate intensity. However, it is unknown if strength training improves RE durability at marathon race intensity, or high-intensity performance akin to the final stages of a competitive race. This study quantified the effect of a supplementary 10-wk strength training program on RE throughout 90 min of running in the heavy-intensity domain, and subsequent fatigued performance in runners. Methods Twenty-eight well-trained male runners (maximal oxygen uptake (V̇O 2max ) 58.6 mL·kg −1 ·min −1 ; 10 km 39:02 mm:ss) were performance-matched and randomly assigned to a habitual running-only control (E; n = 14) or supplementary strength training group (E + S; n = 14) that performed maximal strength and plyometric training twice weekly for 10 wk. Before the training, participants performed a 90-min run at 10% Δ between lactate threshold 1 and 2 (13.1 ± 1.4 km·h −1 , 79.7% V̇O 2max ). RE, quantified as oxygen cost (mL·kg −1 ·km −1 ), was recorded at 15-min intervals during the run, immediately thereafter, participants ran a time to exhaustion (TTE) at 95% pre-test V̇O 2max (16.1 ± 1.6 km·h −1 ). The 90-min run and TTE were repeated after the training intervention. Results A large interaction effect of training–group–run time was found for RE ( P = 0.003, η p 2 = 0.13), with E + S improving versus E at 90 min (−2.1% vs +0.6%; P = 0.04). For TTE, a large group–training interaction effect was detected ( P = 0.004, η p 2 = 0.28), changing by +35% in E + S and −8% in E. Conclusions This study demonstrated that adding maximal strength and plyometrics training to a program of endurance running improved RE durability and substantially increased high-intensity TTE at the end of a 90-min run in the heavy-intensity domain in well-trained male runners.