OAT, WHEAT OR CORN CEREAL INGESTION BEFORE EXERCISE ALTERS METABOLISMIN HUMANS

This study was designed to determine metabolic and physical performanc e responses to ingestion of pre-exercise meals with different macronut rient and fiber profiles. Twelve physically active subjects (6 males a nd 6 females) were used to investigate the metabolic and physical perf ormance consequences of consuming pre-exercise meals consisting of oat , corn, or wheat cereals. A fasting trial served as the control, and a ll subjects received each treatment in a Latin-square design. Blood sa mples were drawn before and 85 min after meal ingestion, during 90 min of cycling exercise (60% VO2peak), after a 6.4 km performance ride, a nd during 60 min of recovery. Expired air samples were collected to de termine nutrient utilization. Resting carbohydrate oxidation rates and plasma insulin concentrations after oat ingestion were less than afte r wheat, and corn and wheat ingestion, respectively (P < 0.05). During exercise, the change in plasma glucose from pre-exercise was greater after consuming wheat and corn compared with oat (P < 0.05), and it wa s inversely related to pre-exercise plasma insulin concentration (r = -0.55, P = 0.0001). Plasma free fatty acid concentrations were inverse ly related to plasma lactate concentrations (r = -0.58, P = 0.0001). F ree Fatty acid concentrations and fat oxidation were greater in fastin g trials than all others, but performance ride times did not differ am ong treatments. Plasma branched-chain amino acid concentrations resemb led their respective meal profiles throughout exercise, the performanc e ride, and recovery. These results indicate that pre-exercise meal co mposition can influence glucose homeostasis during early exercise and plasma branched-chain amino acid concentrations over a substantial ran ge of metabolic demands.