Cognitive processing Efficiency (Throughput) Improves with Aerobic Exercise and is Independent of the Environmental Oxygenation Level: A Randomized Crossover Trial

Aerobic exercise with eicosapentaenoic acid (EPA) may enhance cognition via cerebro-vascular pathways. We tested whether mild hyperbaric oxygen (HBO; 1.41 atmospheres absolute [ATA], approximately 30% O₂) adds to gains in cognitive processing capacity (throughput) versus normobaric normoxia (1.0 ATA, approximately 21% [20.9%] O₂). Young healthy males (n=16) performed cycling exercise at 60–70% VO₂peak for 60 min, twice weekly, for 4 weeks per environment with a 1-week washout; EPA (2,170 mg·day⁻¹) continued for 8 weeks. An EPA-only control (n=8) was included for supplementary analysis. The primary outcome was throughput (correct·min⁻¹; T1–T4); secondary out-comes were interference indices (I1: stroop interference, I2: reverse-stroop interference). Effects were estimated using linear mixed models [environment, time, environment × time; AR(1), REML] and Hedges’ gav; accuracy used generalized estimating equations. Throughput improved mainly with time (T1–T2 p<.001; T4 p=.017; T3 p=.055), with no environment or interaction effects. I1/I2 showed no significant change, and one task ex-hibited an accuracy ceiling. Under safe, feasible conditions (≤1.41 ATA), aerobic exercise improved processing capacity (throughput) independently of environmental oxygenation level. The absence of additive effects may be due to the conservative settings used in this study.