Oxidation of combined ingestion of glucose and sucrose during exercise.

Human Performance Laboratory, School of Sport and Exercise Science, University of Birmingham, Birmingham B15 2TT, UK.
Metabolism (Impact Factor: 3.61). 06/2005; 54(5):610-8. DOI: 10.1016/j.metabol.2004.12.004
Source: PubMed

ABSTRACT The first purpose of the study was to examine whether combined ingestion of glucose and sucrose at an intake rate of 1.2 g/min would lead to higher oxidation rates compared with the ingestion of an isocaloric amount of glucose or sucrose alone. The second aim of the study was to investigate whether a mixture of glucose and sucrose when ingested at a high rate (2.4 g/min) would result in exogenous CHO oxidation rates higher than 1.2 to 1.3 g/min. Eight trained cyclists (maximal oxygen consumption: 64 +/- 2 mL . kg -1 . min -1 , mean +/- SE) performed 5 exercise trials in random order. Each trial consisted of 120 minutes of cycling at 50% maximum power output (63% +/- 2% maximal oxygen consumption), whereas subjects received a solution providing either 1.2 g/min of glucose (GLU), 1.2 g/min of sucrose (SUC), 0.6 g/min of glucose + 0.6 g/min of sucrose (M-GLU+SUC), 1.2 g/min of glucose + 1.2 g/min of sucrose (H-GLU+SUC), or water (WAT). Peak exogenous CHO oxidation rates in the H-GLU+SUC trial (1.20 +/- 0.07 g/min) were significantly higher ( P < .01) compared with the GLU, M-GLU+SUC, and SUC trials (0.77 +/- 0.04, 0.90 +/- 0.07, 0.98 +/- 0.04 g/min, respectively). Furthermore, peak exogenous CHO rates in M-GLU+SUC and SUC trials were significantly higher ( P < .05) compared with the GLU trial. In conclusion, combined ingestion of moderate amounts of glucose and sucrose (144 g) during cycling exercise resulted in approximately 21% higher exogenous CHO oxidation rates compared with the ingestion of an isocaloric amount of glucose. Furthermore, when a mixture of glucose and sucrose was ingested at high rates (2.4 g/min), exogenous CHO oxidation rates reached peak values of approximately 1.20 g/min.

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