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Cited by 101Diet and metabolism studiesMuscle metabolism and nutritionCardiovascular and exercise physiology

Effect of a Ketogenic Diet on Submaximal Exercise Capacity and Efficiency in Runners

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SHAW, DAVID M., MERIEN, FABRICE, BRAAKHUIS, ANDREA, MAUNDER, ED, DULSON, DEBORAH K.·2019·Medicine & Science in Sports & Exercise
DOI 10.1249/mss.0000000000002008
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Abstract

PURPOSE: We investigated the effect of a 31-d ketogenic diet (KD) on submaximal exercise capacity and efficiency. METHODS: A randomized, repeated-measures, crossover study was conducted in eight trained male endurance athletes (V˙O2max, 59.4 ± 5.2 mL⋅kg⋅min). Participants ingested their habitual diet (HD) (13.1 MJ, 43% [4.6 g⋅kg⋅d] carbohydrate and 38% [1.8 g⋅kg⋅d] fat) or an isoenergetic KD (13.7 MJ, 4% [0.5 g·kg⋅d] carbohydrate and 78% [4 g⋅kg⋅d] fat) from days 0 to 31 (P < 0.001). Participants performed a fasted metabolic test on days -2 and 29 (~25 min) and a run-to-exhaustion trial at 70% V˙O2max on days 0 and 31 following the ingestion of a high-carbohydrate meal (2 g⋅kg) or an isoenergetic low-carbohydrate, high-fat meal (<10 g CHO), with carbohydrate (~55 g⋅h) or isoenergetic fat (0 g CHO⋅h) supplementation during exercise. RESULTS: Training loads were similar between trials and V˙O2max was unchanged (all, P > 0.05). The KD impaired exercise efficiency, particularly at >70% V˙O2max, as evidenced by increased energy expenditure and oxygen uptake that could not be explained by shifts in respiratory exchange ratio (RER) (all, P < 0.05). However, exercise efficiency was maintained on a KD when exercising at <60% V˙O2max (all, P > 0.05). Time-to-exhaustion (TTE) was similar for each dietary adaptation (pre-HD, 237 ± 44 vs post-HD, 231 ± 35 min; P = 0.44 and pre-KD, 239 ± 27 vs post-KD, 219 ± 53 min; P = 0.36). Following keto-adaptation, RER >1.0 vs <1.0 at V˙O2max coincided with the preservation and reduction in TTE, respectively. CONCLUSION: A 31-d KD preserved mean submaximal exercise capacity in trained endurance athletes without necessitating acute carbohydrate fuelling strategies. However, there was a greater risk of an endurance decrement at an individual level.

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  • Another group who studied 31 d of LCHF in endurance-trained runners confirmed the findings of impaired exercise economy, but noted that this effect was amplified at intensities above 70% VO2max and was of greater magnitude than could be explained by stoichiometric calculations.

    “Indeed, another group who studied 31 d of LCHF in endurance-trained runners confirmed our findings of impaired exercise economy, but noted that this effect was amplified at intensities above 70% VO2max and was of greater magnitude than could be explained by stoichiometric calculations [61].”

    From Crisis of confidence averted: impairment of exercise economy and performance in elite race walkers by ketogenic low carbohydrate, high fat (LCHF) diet is reproducible (2020) · cites this paper as [61]

  • The substantial increase in muscle fat oxidation achieved by adaptation to a ketogenic low-carbohydrate, high-fat diet is associated with an increase in the oxygen cost of exercise at speeds relevant to the race performance of elite endurance athletes.

    “consistent findings from studies from our group [24,25,26,27] and others [28] that the substantial increase in muscle fat oxidation achieved by adaptation to a ketogenic low-carbohydrate (CHO), high-fat diet is associated with an increase in the oxygen cost of exercise at speeds which are relevant to the race performance of elite endurance athletes [29].”

    From Neither beetroot juice supplementation nor increased carbohydrate oxidation enhance economy of prolonged exercise in elite race walkers (2021) · cites this paper as [28]

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Authors
SHAW, D. M., MERIEN, F., BRAAKHUIS, A., MAUNDER, E., & DULSON, D. K.
Affiliations
  • Auckland University of Technology (NZ)
  • AUT-Roche Diagnostics Laboratory, School of Science, Auckland University of Technology, Auckland, NEW ZEALAND
  • University of Auckland (NZ)
ORCID
Venue
Medicine & Science in Sports & Exercise
Publisher
Ovid Technologies (Wolters Kluwer Health)
Published
2019-04-26
Volume
51
Issue
10
Pages
2135-2146
ISSN
  • 0195-9131 (ISSN-L)
  • 1530-0315
DOI
10.1249/mss.0000000000002008
OpenAlex
W2942074124
Cited by
101
References
39
Citations by year
2026: 8 · 2025: 11 · 2024: 11 · 2023: 18 · 2022: 11 · 2021: 24 · 2020: 14 · 2019: 4
FWCI
9.08
Type
journal article
Language
en
Update notices
correction (2025-09-01)
Open access
Locations
  • Medicine & Science in Sports & Exercise (publishedVersion)
  • PubMed (publishedVersion)
  • Newcastle University ePrints (Newcastle Univesity)
Topics
  • Health Sciences › Medicine › Physiology › Diet and metabolism studies
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Muscle metabolism and nutrition
  • Health Sciences › Medicine › Complementary and alternative medicine › Cardiovascular and exercise physiology
Keywords
ketogenic diet, submaximal exercise capacity, exercise efficiency, endurance runners, time to exhaustion, respiratory exchange ratio, energy expenditure, oxygen consumption, carbohydrate supplementation, dietary fat supplementation, endurance athletes, high-fat diet, carbohydrate restriction, exercise metabolism
MeSH terms
Adult, Blood Glucose, Cardiovascular Physiological Phenomena, Energy Metabolism, Exercise Test, Physical Exertion, Humans, Oxygen Consumption, Perception, Physical Endurance, Physical Fitness, Running, Cross-Over Studies, Lactic Acid, 3-Hydroxybutyric Acid, Diet, Ketogenic, Young Adult, Physical Conditioning, Human

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