Plasma total fatty acid responses to exercise following caffeine ingestion

Abstract

Aerobic exercise is associated with changes in the blood profile of fatty acids. Caffeine is known to be a potential lipolytic agent. Hence, caffeine ingestion in addition to exercise might have an influence on fatty acids, with positive effects on health and performance. The aim of the present study, therefore, was to assess the effect of caffeine (5 mg · kg body mass−1) ingested before aerobic exercise on the total plasma fatty acid profile. In a crossover, double-blind, randomized study involving 20 untrained males ( 43.57±6.48 ml · kg−1 · min−1), blood lactate concentration, plasma caffeine values, and plasma fatty acid profile were examined using chromatographic techniques before and after 30 min of steady-state cycle exercise at 75% under placebo and caffeine conditions. Ventilatory responses and substrate oxidation rates were determined during exercise and recovery. Ventilatory responses, lactate concentrations, and fat and carbohydrate oxidation rates were not affected by caffeine ingestion. Carbohydrate was the main substrate oxidized during steady-state trials under both conditions, although exercise increased blood saturated fatty acids (placebo: 28.30±5.90% vs. 31.09±4.59, P<0.05; caffeine: 28.88±4.12% vs. 29.60±4.56%). Unsaturated blood concentrations of oleic fatty acid trans (C18:1t) increased due to caffeine (placebo: 2.22±2.81% vs. 2.61±3.86%; caffeine 1.53±0.19% vs. 1.70±0.49%, P<0.05). In conclusion, the ingestion of caffeine prior to moderate-to-high aerobic exercise may not have a clear metabolic advantage under the conditions of the present study in untrained individuals, although it might influence some individual unsaturated fatty acids (C18:1t) despite low fat oxidation rates.