Cited by 35Muscle metabolism and nutritionCardiovascular and exercise physiologyExercise and Physiological Responses

Carbohydrate, protein, and fat metabolism during exercise after oral carnitine supplementation in humans

Broad, Elizabeth M., Maughan, Ronald J., Galloway, Stuart D.R·2008·International Journal of Sport Nutrition and Exercise Metabolism

Abstract

Twenty nonvegetarian active males were pair-matched and randomly assigned to receive 2 g of L-carnitine L-tartrate (LC) or placebo per day for 2 wk. Participants exercised for 90 min at 70% VO2max after 2 days of a prescribed diet (M +/- SD: 13.6 +/- 1.6 MJ, 57% carbohydrate, 15% protein, 26% fat, 2% alcohol) before and after supplementation. Results indicated no change in carbohydrate oxidation, nitrogen excretion, branched-chain amino acid oxidation, or plasma urea during exercise between the beginning and end of supplementation in either group. After 2 wk of LC supplementation the plasma ammonia response to exercise tended to be suppressed (0 vs. 2 wk at 60 min exercise, 97 +/- 26 vs. 80 +/- 9, and 90 min exercise, 116 +/- 47 vs. 87 +/- 25 micromol/L), with no change in the placebo group. The data indicate that 2 wk of LC supplementation does not affect fat, carbohydrate, and protein contribution to metabolism during prolonged moderate-intensity cycling exercise. The tendency toward suppressed ammonia accumulation, however, indicates that oral LC supplementation might have the potential to reduce the metabolic stress of exercise or alter ammonia production or removal, which warrants further investigation.

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Crossref · 10.1123/ijsnem.18.6.567

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31 of 31 references verified0 citation errors · 0 not checkable

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  • Research investigating the impact of carnitine supplementation on muscle fuel metabolism and/or exercise performance has produced inconclusive results.

    “To date, research investigating the impact of carnitine supplementation on muscle fuel metabolism and/or exercise performance has produced inconclusive results [[185], [186], [187], [188], [189], [190], [191]].”

    From Nutritional Considerations for the Vegan Athlete (2023) · cites this paper as [187]

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Authors
Broad, E. M., Maughan, R. J., & Galloway, S. D. R.
Affiliations
University of Stirling (GB)
Venue
International Journal of Sport Nutrition and Exercise Metabolism
Published
2008-12
Volume
18
Issue
6
Pages
567-584
ISSN
  • 1526-484X (ISSN-L)
  • 1543-2742
OpenAlex
W1563717935
Cited by
35
References
31
Citations by year
2026: 3 · 2025: 3 · 2024: 1 · 2023: 3 · 2022: 1 · 2021: 2 · 2020: 4 · 2018: 6 · 2017: 2 · 2015: 1 · 2014: 2 · 2012: 1
FWCI
0.87
Type
journal article
Language
en
Open access
closed
Locations
  • International Journal of Sport Nutrition and Exercise Metabolism (publishedVersion)
  • PubMed (publishedVersion)
  • Stirling Online Research Repository (University of Stirling) (submittedVersion, public-domain)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Muscle metabolism and nutrition
  • Health Sciences › Medicine › Complementary and alternative medicine › Cardiovascular and exercise physiology
  • Health Sciences › Medicine › Rehabilitation › Exercise and Physiological Responses
Keywords
exercise metabolism, carbohydrate oxidation, fat oxidation, protein oxidation, branched-chain amino acids, nitrogen excretion, blood ammonia
MeSH terms
Adult, Amino Acids, Ammonia, Bicycling, Blood Urea Nitrogen, Carnitine, Double-Blind Method, Exercise Test, Humans, Male, Nitrogen, Proteins, Tartrates, Exercise, Dietary Supplements, Carbohydrate Metabolism, Lipid Metabolism, Young Adult

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