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Preexercise galactose and glucose ingestion on fuel use during exercise

O’HARA, JOHN P.; COOKE, CARLTON B.; MORRISON, DOUGLAS J.; KING, RODERICK F. G. J.; King, Roderick F. G. J.; Carroll, Sean; Cooke, Carlton B.; King, Roderick F.G.J.; Morrison, Douglas J.; O'Hara, John P.; Preston, Thomas

Authors

JOHN P. O’HARA

CARLTON B. COOKE

DOUGLAS J. MORRISON

RODERICK F. G. J. KING

Roderick F. G. J. King

John P. O'Hara

Carlton B. Cooke

Douglas J. Morrison

Thomas Preston

Roderick F.G.J. King

Abstract

Purpose: This study determined the effect of ingesting galactose and glucose 30 min before exercise on exogenous and endogenous fuel use during exercise. Methods: Nine trained male cyclists completed three bouts of cycling at 60% Wmax for 120 min after an overnight fast. Thirty minutes before exercise, the cyclists ingested a fluid formulation containing placebo, 75 g of galactose (Gal), or 75 g of glucose (Glu) to which ¹³C tracers had been added, in a double-blind randomized manner. Indirect calorimetry and isotope ratio mass spectrometry were used to calculate fat oxidation, total carbohydrate (CHO) oxidation, exogenous CHO oxidation, plasma glucose oxidation, and endogenous liver and muscle CHO oxidation rates. Results: Peak exogenous CHO oxidation was significantly higher after Glu (0.68 ± 0.08 g·min⁻¹, P < 0.05) compared with Gal (0.44 ± 0.02 g·min⁻¹); however, mean rates were not significantly different (0.40 ± 0.03 vs. 0.36 ± 0.02 g·min⁻¹, respectively). Glu produced significantly higher exogenous CHO oxidation rates during the initial hour of exercise (P < 0.01), whereas glucose rates derived from Gal were significantly higher during the last hour (P < 0.01). Plasma glucose and liver glucose oxidation at 60 min of exercise were significantly higher for Glu (1.07 ± 0.1 g·min⁻¹, P < 0.05, and 0.57 ± 0.08 g·min⁻¹, P < 0.01) compared with Gal (0.64 ± 0.05 and 0.29 ± 0.03 g·min⁻¹, respectively). There were no significant differences in total CHO, whole body endogenous CHO, muscle glycogen, or fat oxidation between conditions. Conclusion: The preexercise consumption of Glu provides a higher exogenous source of CHO during the initial stages of exercise, but Gal provides the predominant exogenous source of fuel during the latter stages of exercise and reduces the reliance on liver glucose.

Journal Article Type Article
Publication Date Oct 1, 2012
Journal Medicine & science in sports & exercise
Print ISSN 0195-9131
Electronic ISSN 1530-0315
Publisher Lippincott, Williams & Wilkins
Peer Reviewed Peer Reviewed
Volume 44
Issue 10
Pages 1958-1967
DOI https://doi.org/10.1249/MSS.0b013e318258bf85
Keywords Physical Therapy, Sports Therapy and Rehabilitation; Orthopedics and Sports Medicine
Publisher URL http://ovidsp.tx.ovid.com/sp-3.20.0b/ovidweb.cgi?QS2=434f4e1a73d37e8ce55b227ffaae5fa153836cd2424090755461d69c9b091468fac1d74597fb0910f725d2315ab615a7c929f8d84d6983d174cb5654d1e7301c9974a0343942921cc0f0211b250d1de515bcfd1841c35246d1d4675db73f1373796eadb32c
Additional Information Authors' accepted manuscript of article published in: Medicine & science in sports & exercise, 2012, v.4, issue 10

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