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JENTJENS, R. L. P. G., J. ACHTEN, and A. E. JEUKENDRUP. High Oxidation Rates from Combined Carbohydrates Ingested during Exercise. Med. Sci. Sports Exerc., Vol. 36, No. 9, pp. 1551–1558, 2004. Studies that have investigated oxidation of a single carbohydrate (CHO) during exercise have reported oxidation rates of up to 1 g·min−1. Recent studies from our laboratory have shown that a mixture of glucose and sucrose or glucose and fructose ingested at a high rate (1.8 g·min−1) leads to peak oxidation rates of ~1.3 g·min−1 and results in ~20 to 55% higher exogenous CHO oxidation rates compared with the ingestion of an isocaloric amount of glucose.The purpose of the present study was to examine whether a mixture of glucose, sucrose and fructose ingested at a high rate would result in even higher exogenous CHO oxidation rates (>1.3 g·min−1).Eight trained male cyclists (V̇O2max: 64 ±·kg−1 BM·min−1) cycled on three different occasions for 150 min at 62 ± 1% V̇O2max and consumed either water (WAT) or a CHO solution providing 2.4 g·min−1 of glucose (GLU) or 1.2 g·min−1 of glucose + 0.6 g·min−1 of fructose + 0.6 g·min−1 of sucrose (MIX).High peak exogenous CHO oxidation rates were found in the MIX trial (1.70 ± 0.07 g·min−1), which were ~44% higher (P < 0.01) compared with the GLU trial (1.18 ± 0.04 g·min−1). Endogenous CHO oxidation was lower (P < 0.05) in MIX compared with GLU (0.76 ± 0.12 and 1.05 ± 0.06 g·min−1, respectively).When glucose, fructose and sucrose are ingested simultaneously at high rates (2.4 g·min−1) during cycling exercise, exogenous CHO oxidation rates can reach peak values of ~1.7 g·min−1 and estimated endogenous CHO oxidation is reduced compared with the ingestion of an isocaloric amount of glucose.