Exercise-induced changes in the concentration of individual fatty acids and triacylglycerols of human plasma

Abstract

Nineteen male handball players played for two 30-minute periods with a 10-minute interval. Blood samples were drawn at rest, at halftime, and at the end of the game. A biopsy of subcutaneous fat was also taken from 14 participants. Mean plasma lactate concentration was not greater than 4 mmol/L at the end of either half. The concentration of nonesterified fatty acids (NEFA) in plasma increased gradually but not uniformly throughout the game. In effect, the percentages of the major NEFA were significantly different at the three time points of sampling: palmitate (16:0) and stearate (18:0) decreased and oleate (18:1) and linoleate (18:2) increased, resulting in an increase of the ratio of unsaturated to saturated fatty acids ( U S ) from 1.1 at rest to 1.6 at the end. The concentration of plasma triacylglycerols (TG) declined during the game, but nine of 19 subjects showed increases during one or both halves, implying a stimulation of TG release from the liver during exercise, which can, at times, overcome the increased hydrolysis of TG in muscle capillaries. Changes in the acyl-group distribution of plasma TG were minor but also in favor of unsaturated fatty acids. Changes in NEFA composition tended toward the composition of adipose tissue, in which TG had a U S ratio of 3.2. Linear regression between changes in the total concentration of plasma NEFA during each half of the game and corresponding changes in the concentration of individual NEFA showed that the contributions (slopes) of myristate (14:0), palmitoleate (16:1), 18:0, and 18:2 were not significantly different from their fractions in adipose tissue TG. In contrast, the contributions of 16:0 and 18:1 were, respectively, higher and lower than their fractions in adipose tissue TG, suggesting that the rates of release were, respectively, higher and lower than the rates of uptake. The observed shift toward unsaturated NEFA and TG may contribute to the favorable modifications of the plasma lipoprotein profile associated with aerobic exercise and with a diet rich in unsaturated fatty acids.