Pectin-alginate does not further enhance exogenous carbohydrate oxidation in running: Hydrogel and exogenous carbohydrate oxidation

James Barber, Joel Thomas, Ben Narang, Aaron Hengist, James Betts, Gareth Wallis, Javier Gonzalez

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PURPOSE: Maximizing carbohydrate availability is important for many endurance events. Combining pectin and sodium alginate with ingested maltodextrin-fructose (MAL+FRU+PEC+ALG) has been suggested to enhance carbohydrate delivery via hydrogel formation but the influence on exogenous carbohydrate oxidation remains unknown. The primary aim of this study was to assess the effects of MAL+FRU+PEC+ALG on exogenous carbohydrate oxidation during exercise compared to a maltodextrin-fructose mixture (MAL+FRU). MAL+FRU has been well established to increase exogenous carbohydrate oxidation during cycling, compared to glucose-based carbohydrates (MAL+GLU). However, much evidence focuses on cycling, and direct evidence in running is lacking. Therefore, a secondary aim was to compare exogenous carbohydrate oxidation rates with MAL+FRU versus MAL+GLU during running. METHODS: Nine trained runners completed two trials (MAL+FRU and MAL+FRU+PEC+ALG) in a double-blind, randomised crossover design. A subset (n=7) also completed a MAL+GLU trial to address the secondary aim, and a water trial to establish background expired 13CO2 enrichment. Participants ran at 60% \dot{\mathrm{V}}\mathrm{O}_\mathrm{2}peak for 120 min while ingesting either water only, or carbohydrate solutions at a rate of 1.5 g carbohydrate·min-1. RESULTS: At the end of 120 min of exercise, exogenous carbohydrate oxidation rates were 0.9 (SD 0.5) g·min-1 with MAL+GLU ingestion. MAL+FRU ingestion increased exogenous carbohydrate oxidation rates to 1.1 (SD 0.3) g·min-1 (p=0.038), with no further increase with MAL+FRU+PEC+ALG ingestion (1.1 (SD 0.3) g·min-1; p=1.0). No time x treatment interaction effects were observed for plasma glucose, lactate, insulin or non-esterified fatty acids, nor for ratings of perceived exertion or gastrointestinal symptoms (all p>0.05). CONCLUSION: To maximise exogenous carbohydrate oxidation during moderate-intensity running, athletes may benefit from consuming glucose(polymer)-fructose mixtures over glucose-based carbohydrates alone, but the addition of pectin and sodium alginate offers no further benefit.
Original languageEnglish
Pages (from-to)1376-1384
JournalMedicine & Science in Sports & Exercise
Issue number6
Publication statusPublished - 30 Jun 2020


  • fructose
  • glucose
  • hydrogel
  • metabolism
  • sports nutrition


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