Exercise-induced hypoxaemia in master athletes: effects of a polyunsaturated fatty acid diet

Abstract

Exercise-induced hypoxaemia (EIH) has been associated with an oxygen diffusion limitation. Because polyunsaturated fatty acids (PUFA) administration can modify cell membrane fluidity, we hypothesized that the importance of EIH could be reduced after a 6-week PUFA diet. Resting pulmonary functions and a maximal cycling test were performed before and after the diet, in eight master athletes [48 (SD 6 years)]. The partial pressure. of O₂ in arterial blood (PaO₂), alveolar ventilation ($\dot V_A$) and ideal alveolar-arterial oxygen partial pressure difference (P(A _i−a)O₂) were obtained at each exercise intensity. The extent of EIH at maximal exercise was significantly lower after PUFA [P_aO₂ −17.2 (SEM 1.9) vs −12.9 (SEM 2.2)]. Before PUFA,$\dot V_A$ accounted for 50% of the variance in the fall inP(A _i−a) for intensities below 80% maximal oxygen uptake ($\dot VO_{2\max }$) andP(A _i−a)O₂ for 60% between 70% and 100%$\dot VO_{2\max }$. After PUFA, the reduction in EIH was highly correlated (r ² = 0.85;P < 0.001) to resulting changes inP(A_ii−a)O₂ and resting pulmonary diffusing capacity$(D_{L_{CO} } )/\dot V_A$ but not with changes in ideal alveolar partial pressure of oxygen. The improvement in EIH following PUFA could be related to an increase in alveolar-arterial oxygen conductance following improved pulmonary diffusion.