From Metabolism to Medals: Contemporary Perspectives and Revisiting Carbohydrate Guidelines for Fuelling Endurance Athletes During Exercise

Morton, JP ORCID: 0000-0003-2776-2542, Fell, JM, Gonzalez, JT, Hearris, MA, Podlogar, T, Pugh, JN ORCID: 0000-0002-5930-4709 and Wallis, GA (2026) From Metabolism to Medals: Contemporary Perspectives and Revisiting Carbohydrate Guidelines for Fuelling Endurance Athletes During Exercise. The Journal of Nutrition. ISSN 0022-3166

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Abstract

The effects of carbohydrate (CHO) intake on substrate metabolism, exercise capacity and exercise performance have been studied for over 100 years. From a metabolic perspective, the ergogenic effect of CHO intake is likely mediated by liver (and potentially muscle) glycogen sparing, maintenance of plasma glucose concentrations and whole-body CHO oxidation rates, such that the required exercise intensity can be sustained for a longer duration thereby delaying fatigue. Accordingly, the 2016 sport nutrition guidelines from the American College of Sports Medicine recommend CHO intakes up to 90 g per hour (from multiple transportable carbohydrates e.g. glucose/fructose mixtures), as targeted to exercise that is >2.5 to 3 h in duration. Although field observations report a trend for endurance athletes to consume (and experiment with) higher rates of CHO ingestion during training and racing (i.e. 120-200 g.h), the efficacy of such doses is not yet substantiated by current scientific research. Rather, contemporary research suggests that the upper limit of CHO intake could increase from 90 to 120 g.h (at least for trained participants), considering that both exogenous and whole-body rates of CHO oxidation can be increased with these higher ingestion rates. Such absolute doses may also modulate important physiological determinants of performance (e.g. durability and economy) across cycling, marathon running and ultra-endurance exercise. As such, the present paper provides a contemporary review of CHO metabolism during exercise, factors affecting exogenous CHO oxidation rates (i.e. CHO blend, ratio, format, environmental considerations etc) and sport-specific research (alongside personal author insights from practice), before presenting an updated and more nuanced model to guide CHO personalisation strategies for endurance athletes. Directions for future research are also discussed, emphasising the need for collaborative research to study both male and female athletes during ecologically valid exercise protocols that better address the real-world fuelling challenges faced by elite athletes.

Item Type:	Article
Uncontrolled Keywords:	cycling; fructose; glucose; maltodextrin; marathon; ultra-endurance; 30 Agricultural, Veterinary and Food Sciences; 32 Biomedical and Clinical Sciences; 3210 Nutrition and Dietetics; 3003 Animal Production; 3006 Food Sciences; Nutrition; Obesity; Physical Activity; 0702 Animal Production; 0908 Food Sciences; 1111 Nutrition and Dietetics; Nutrition & Dietetics; 3003 Animal production; 3006 Food sciences; 3210 Nutrition and dietetics
Subjects:	R Medicine > RC Internal medicine > RC1200 Sports Medicine
Divisions:	Sport and Exercise Sciences
Publisher:	Elsevier BV
Date of acceptance:	20 February 2026
Date of first compliant Open Access:	16 March 2026
Date Deposited:	16 Mar 2026 14:09
Last Modified:	16 Mar 2026 14:10
DOI or ID number:	10.1016/j.tjnut.2026.101442
URI:	https://researchonline.ljmu.ac.uk/id/eprint/28250

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