Effects of Chronic Omega-3 Fatty Acid Supplementation on Erythrocyte Deformability and Muscle Microvascular Oxygenation in Endurance Trained Cyclists

Abstract

The ability to perform endurance exercise is dependent on the transport of oxygen to the active skeletal muscles. For oxygen to perfuse into the skeletal muscle, flexibility of red blood cells is crucial in determining the passage through narrow capillaries, thus the erythrocytes must deform to increase regional blood flow through the microvasculature. It has been shown at submaximal exercise and in conditions of acute hypoxia, erythrocyte deformability is decreased, however supplementation of omega-3 polyunsaturated fatty acids (PUFAs) has been shown to increase erythrocyte deformability. PURPOSE: The purpose of this study is to determine the effects of chronic omega-3 fatty acid supplementation on erythrocyte deformability and tissue oxygenation in highly trained cyclists during submaximal exercise in both normoxic and hypoxic conditions. METHODS: The protocol was performed on thirteen highly trained cyclists (VO2 max ≥55ml/kg/min). The subjects were divided into treatment (2g of DHA, 3g of EPA, and 100mg of Vitamin E) and placebo (safflower oil) groups. The subjects’ visits pre- and postsupplementation followed identical protocols with one visit occurring in normoxia and the other in acute hypoxia (FIO2 =15%). Each visit involved 2 submaximal cycling bouts of 3 minutes, equaling 25% and 50% of peak power, and one bout at 75% of peak power to exhaustion. Erythrocyte elongation index (EI) and near infrared spectroscopy (NIRS) measures were recorded for each trial. RESULTS: There were no significant differences in Elongation Index (EI) when comparing baseline values to measurements taken post-exercise in the hypoxic condition prior to supplementation. After supplementation, there were no significant differences in baseline EI when compared to pre-supplementation values. After the hypoxic exercise trial, EI at 20 Pa of shear stress was significantly greater 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 postsupplementation in the PUFA group compared to the placebo group (PUFA: 0.580 ± 0.003; placebo: 0.574 ± 0.006; p<0.05).There were no significant difference in any of the NIRS measures any common workload CONCLUSION: Erythrocye deformability did not decrease with exercise in hypoxia, nor did baseline levels change with omega-3 supplementation, and only a marginal significant difference on post-exercise erythrocyte deformability measures was demonstrated. There was no effect on microvascular tissue oxygenation measures.