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Ketone ester supplementation did not improve performance, cognitive function, or sleep during an 8-day simulated cycling race

In a double-blind, placebo-controlled trial, 18 well-trained cyclists completed an 8-day simulated cycling stage race. Ketone monoester supplementation (25g twice daily) did not improve exercise performance, sleep, or cognitive function compared to placebo. The race induced fatigue (peak heart rate drop ~11 bpm, time trial performance drop ~3%), but no clear benefit of KE was observed.

Last updated: Aug 29, 2026•1 RCTs•📖 Read as article →

Evidence Score

Evidence Score42/100
Human RCT★★☆☆☆
Meta-analysis☆☆☆☆☆
Mechanism★★★★★
Safety★★★★☆
Confidencelow

Study Evidence

Study 1. Ketone Ester Intake Did Not Improve Performance, Neither Cognitive Function or Sleep, During an 8-Day Simulated Cycling Race.

observational

Engelbrecht L, Lauriks W, Robberechts R, Stalmans M, Ramaekers M, Terblanche E, Koppo K, Poffé C · Medicine and science in sports and exercise (2026)

Participants: N/A
Duration: 8 days
Intervention: 25g ketone monoester (KE) supplementation immediately after each stage and 30 minutes before sleep
Outcome: Exercise performance (30-min time trial), sleep quantity and quality, cognitive function, physiological strain, recovery markers
Effect Size: N/A
Population: Well-trained cyclists (n=18) participating in an 8-day simulated cycling stage race

Result:

PubMed: 42658808DOI: 10.1249/MSS.0000000000004119

Mechanism Graph

Ketone esters increase blood ketone levels
↓
Expected to enhance post-exercise recovery and reduce mental fatigue
↓
Hypothesized to improve sleep and subsequent performance
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Result: No significant improvement in performance, sleep, or cognitive function

Limitations

  • ⚠Small sample size (n=18) with uneven group distribution (KE n=8, CON n=10)
  • ⚠Simulated race may not fully replicate real-world multi-day event conditions
  • ⚠No direct measurement of cognitive function reported in abstract (only mentioned in title/context)

Frequently Asked Questions

Did ketone ester supplementation improve cycling performance in this study?▼

No, ketone ester supplementation did not improve 30-minute time trial performance or other performance measures during the 8-day simulated race.

Did ketone esters affect sleep quality or quantity?▼

No, neither the KE supplementation nor the race had a significant impact on sleep, as measured daily during the study.

What was the dose and timing of ketone ester intake?▼

Participants received 25g of ketone monoester immediately after each stage and 30 minutes before sleep, totaling 50g per day.

Who were the participants in this study?▼

Eighteen well-trained cyclists, with 8 in the ketone ester group and 10 in the placebo group, completed the 8-day simulated cycling race.

Products

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References

  1. 1.Engelbrecht L, Lauriks W, Robberechts R, Stalmans M, Ramaekers M, Terblanche E, Koppo K, Poffé C. "Ketone Ester Intake Did Not Improve Performance, Neither Cognitive Function or Sleep, During an 8-Day Simulated Cycling Race.." Medicine and science in sports and exercise, 2026. PMID: 42658808 DOI: 10.1249/MSS.0000000000004119
Disclaimer: This content is for educational purposes only and is not medical advice. Evidence scores reflect the quality and quantity of available research, not clinical recommendations. Always consult a healthcare professional before starting any supplement or intervention.