CHRONIC OMEGA-3 SUPPLEMENTATION AND ERYTHROCYTE DEFORMABILITY, OXYGEN CONSUMPTION, AND PERFORMANCE DURING NORMOBARIC HYPOXIC EXERCISE

Abstract

O2 delivery is dependent upon the ability of erythrocytes (diameter of ~8µm) to deform and to pass through the smaller microvasculature (~3µm). Reduced erythrocyte deformability in hypoxia could ultimately compromise O2 delivery to the microvasculature of skeletal muscles during exercise, thus impairing performance. Chronic supplementation with omega-3 fatty acids (PUFAs) has been shown to increase erythrocyte deformability, which may improve oxygenation and endurance exercise performance in acute hypoxia. PURPOSE: To determine if chronic ω-3 PUFA supplementation improves erythrocyte deformability, V̇O2, and cycling time to exhaustion during acute hypoxic exercise. METHODS: Thirteen young, healthy, endurance-trained subjects were divided into PUFA (V̇O2max=60.2 ± 4.5 mL.kg-1.min-1, n=6) and placebo (66.2 ± 4.1 mL.kg-1.min-1, n=7) groups. Subjects completed 6 weeks of supplementation with either ω-3 PUFAs (PUFA group; 3g EPA, 2g DHA/day) or placebo (placebo group; safflower oil). Subjects performed identical experimental sessions in acute normobaric hypoxia (FIO2=15%) pre- and post-supplementation that consisted of 3 min cycling / 10 min rest at 25% and 50% of normoxic peak power, as well as cycling to exhaustion at 75% of normoxic peak power. Erythrocyte elongation index (EI) via ektacytometry, V̇O2, and time to exhaustion were recorded for each trial. RESULTS: EI at 20 Pa of shear stress was significantly greater (e.g. higher deformability) within the PUFA group post-supplementation (pre: 0.574 ± 0.004; post: 0.580 ± 0.003; p<0.05). EI at 20 Pa was significantly greater post-supplementation in the PUFA group compared to the placebo group (PUFA: 0.580 ± 0.003; placebo: 0.574 ± 0.006; p<0.05). V̇O2 only during the 50% trial was significantly greater within the PUFA group post-supplementation compared to pre, while no significant differences in V̇O2 were seen between groups at 25%, 50%, or 75% of peak power, or at exhaustion. No significant improvements were seen in time to exhaustion within either group and no difference was seen between groups. CONCLUSION: In acute hypoxia, chronic PUFA supplementation significantly, but marginally (1%) improves erythrocyte deformability, but does not have a significant effect on oxygen uptake or performance.