EXERCISE-INDUCED HYPOXEMIA IN MASTER ATHLETES - EFFECTS OF A POLYUNSATURATED FATTY-ACID DIET

Exercise-induced hypoxaemia (EIH) has been associated with an oxygen d iffusion limitation. Because polyunsaturated fatty acids (PUFA) admini stration can modify cell membrane fluidity, we hypothesized that the i mportance of EIH could be reduced after a 6-week PUFA diet. Resting pu lmonary functions and a maximal cycling test were performed before and after the diet, in eight master athletes [48 (SD 6 years)]. The parti al pressure of O-2 in arterial blood (PaO2), alveolar ventilation (V-A ) and ideal alveolar-arterial oxygen partial pressure difference (P-(A i-a) O-2) were obtained at each exercise intensity. The extent of EIH at maximal exercise was significantly lower after PUFA[PaO2 -17.2 (SEM 1.9) vs -12.9 (SEM 2.2)]. Before PUFA, V-A accounted for 50% of the v ariance in the fall in P-(Ai-a) for intensities below 80% maximal oxyg en uptake (VO2max) and P-(Ai-a)O-2 for 60% between 70% and 100% VO2max . After PUFA, the reduction in EIH was highly correlated (r(2) = 0.85; P<0.001) to resulting changes in P-(Ai-a)O-2 and resting pulmonary di ffusing capacity (D-LCO)/V-A but not with changes in ideal alveolar pa rtial pressure of oxygen. The improvement in EIH following PUFA could be related to an increase in alveolar-arterial oxygen conductance foll owing improved pulmonary diffusion.