Strength training improves running economy durability and fatigued high-intensity performance in well-trained male runners: A randomized control trial

<p dir="ltr"><b>Introduction</b>: Strength training improves running economy (RE) in a non-fatigued 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-week strength training program on RE throughout 90 min of running in the heavy-intensity domain, and subsequent fatigued performance in runners.</p><p dir="ltr"><b>Methods</b>: Twenty-eight well-trained male runners (maximal oxygen uptake (<i>V̇O</i>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 weeks. Before the training, participants performed a 90 min run at 10% Δ between lactate threshold 1 and 2 (13.1±1.4 km/h, 79.7% <i>V̇O</i>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 <i>V̇O</i>₂max (16.1±1.6 km/h). The 90 min run and TTE were repeated after the training intervention.</p><p dir="ltr"><b>Results</b>: A large interaction effect of training x group x run time was found for RE (p=0.003, η_p ²=0.13), with E+S improving vs E at 90 min (-2.1% vs +0.6; p=0.04). For TTE, a large group x training interaction effect was detected (p=0.004, η_p ²=0.28), changing by +35% in E+S and -8% in E.</p><p dir="ltr"><b>Conclusions</b>: This study demonstrated that adding strength and plyometrics training to a programme 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.</p>