13C-glucose-fructose labeling reveals comparable exogenous CHO oxidation during exercise when consuming 120 g/h in fluid, gel, jelly chew, or coingestion: CHO oxidation from fluid, semi-solid and solid

Mark A. Hearris, Jamie N. Pugh, Carl Langan-Evans, Stephen J. Mann, Louise Burke, Trent Stellingwerff, Javier T. Gonzalez, James P. Morton

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We examined the effects of carbohydrate (CHO) delivery form on exogenous CHO oxidation, gastrointestinal discomfort, and exercise capacity. In a randomized repeated-measures design [after 24 h of high CHO intake (8 g·kg ₋1) and preexercise meal (2 g·kg ₋1)], nine trained males ingested 120 g CHO·h ₋1 from fluid (DRINK), semisolid gel (GEL), solid jelly chew (CHEW), or a coingestion approach (MIX). Participants cycled for 180 min at 95% lactate threshold, followed by an exercise capacity test (150% lactate threshold). Peak rates of exogenous CHO oxidation (DRINK 1.56 ± 0.16, GEL 1.58 ± 0.13, CHEW 1.59 ± 0.08, MIX 1.66 ± 0.02 g·min ₋1) and oxidation efficiency (DRINK 72 ± 8%, GEL 72 ± 5%, CHEW 75 ± 5%, MIX, 75 ± 6%) were not different between trials (all P > 0.05). Despite ingesting 120 g·h ₋1, participants reported minimal symptoms of gastrointestinal distress across all trials. Exercise capacity was also not significantly different (all P > 0.05) between conditions (DRINK 446 ± 350, GEL 529 ± 396, CHEW 596 ± 416, MIX 469 ± 395 s). Data represent the first time that rates of exogenous CHO oxidation (via stable isotope methodology) have been simultaneously assessed with feeding strategies (i.e., preexercise CHO feeding and the different forms and combinations of CHO during exercise) commonly adopted by elite endurance athletes. We conclude that 120 g·h ₋1 CHO (in a 1:0.8 ratio of maltodextrin or glucose to fructose) is a practically tolerable strategy to promote high CHO availability and oxidation during exercise. NEW & NOTEWORTHY We demonstrate comparable rates of exogenous CHO oxidation from fluid, semisolid, solid, or a combination of sources. Considering the sustained high rates of total and exogenous CHO oxidation and relative lack of gastrointestinal symptoms, consuming 120 g CHO·h ₋1 appears to be a well-tolerated strategy to promote high CHO availability during exercise. Additionally, this is the first time that rates of exogenous CHO oxidation have been assessed with feeding strategies (e.g., coingestion of multiple CHO forms) typically reported by endurance athletes.

Original languageEnglish
Pages (from-to)1394-1406
Number of pages13
JournalJournal of Applied Physiology
Issue number6
Early online date21 Apr 2022
Publication statusPublished - 1 Jun 2022

Bibliographical note

Funding Information:
This study was funded by a research grant from Science in Sport PLC.

Funding Information:
S.J.M. is employed by Science in Sport PLC (SiS). J.P.M. is a consultant for SiS. SiS, GlaxoSmithKline (GSK), and Lucozade Ribena Suntory (LRS) have previously funded J.P.M.’s research on glycogen metabolism and exercise. J.T.G. is an investigator on research grants funded by Biotechnology and Biological Sciences Research Council (BBSRC), Medical Research Council (MRC), British Heart Foundation, The Rank Prize Funds, The European Society for Clinical Nutrition and Metabolism (ESPEN), LRS, ARLA Foods Ingredients, and Kenniscentrum Suiker and Voeding and has completed paid consultancy for PepsiCo and SVGC. L.B. is a consultant for SiS, for which she does not receive remuneration. Her previous studies related to CHO and sports performance have been funded by the Australian Institute of Sport, Australian Catholic University, and the Alliance for Potato Research and Education, and she has received honoraria for conference presentations by Gatorade Sport Science Institute (GSSI, PepsiCo). T.S. is a consultant for SiS, has done previous consultancy work for GSSI (PepsiCo), and was formerly employed by Nestec/PowerBar. T.S.’s research is currently funded by Own The Podium i4G grants, 94Forward, B2ten, MITACS, and the Wu Tsai Performance Alliance. J.N.P. is a consultant for Aliment Nutrition. Aliment Nutrition have previously funded J.N.P.’s research on probiotic supplementation and substrate metabolism. None of the other authors has any conflicts of interest, financial or otherwise, to disclose.


  • fructose
  • maltodextrin
  • metabolism
  • stable isotopes

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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