Does Hypoxic Training Improve Running Economy and Performance of Elite and Competitive Middle- and Long-Distance Runners? A Systematic Review With Meta-Analysis of Randomized Controlled Trials

ABSTRACT: Schwalm, LC, Pilat, C, Nolte, S, Gatterer, H, Krüger, K, and Hollander, K. Does hypoxic training improve running economy and performance of elite and competitive middle- and long-distance runners? A systematic review with meta-analysis of randomized controlled trials. J Strength Cond Res XX(X): 000-000, 2026-Altitude training (AT) is used to improve endurance performance in competitive running. The aim of this systematic review was to determine whether hypoxic training interventions affect running economy (RE) and performance of competitive runners compared with training under normoxic conditions. Randomized controlled trials (RCTs) were included if they (a) consisted any exposure to hypoxia over a period of ≥3 weeks while performing an endurance exercise training during the same period, and (b) included RE, time trial (TT), time-to-exhaustion (TTE) tests or V̇o2max under normoxic conditions, and (c) included competitive distance runners. Sixteen RCTs were included in the review and 13 in the meta-analysis. The number of subjects in the included studies were n = 182 (11% women) for RE, n = 95 (19% women) for V̇o2max, n = 134 for TT (14% women), and n = 81 (4% women) for TTE. The meta-analysis showed no impact of AT on RE (standardized mean difference (SMD): -0.2; 95% confidence interval (CI): -0.58-0.19; p = 0.31; I2 = 33%). No impact was found for V̇o2max (SMD: 0.33; 95% CI: -0.72 to 1.37; p = 0.54; I2 = 82%) and TT (SMD: -0.34; 95% CI: -0.80 to 0.13; p = 0.16; I2 = 42%). Altitude training showed superiority in improving TTE compared with normoxic training (SMD: 0.89; 95% CI: 0.12- 1.66; p = 0.02; I2 = 56%). Available RCTs do not support an improvement in RE, V̇o2max, and TT when AT was compared with normoxic training. Future RCTs should specifically investigate effects of AT on RE in elite athletes.