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Effect of six weeks ubiquinol supplementation on mitochondrial respiratory function and exercise capacity in healthy males

Jarred P Acton, Nehal S Alsharif, Jack W Bond, Stuart P Cocksedge, Abbie G Mclellan, Donald L Peden, Mark P Funnell, Hannah F Dugdale, Lewis J James, Richard A Ferguson, Tom Clifford, Stephen J Bailey
European Journal of Applied Physiology 2026 126(9):4763-4778

Bibliography

PubMed
PMID 42249931
PubMed Central
PMC13541835
DOI
10.1007/s00421-026-06275-w
Funding
Doctoral research was match-funded by Kaneka Pharma Europe and Loughborough University.
Competing interests
Kaneka Pharma Europe match-funded the doctoral research and analyzed blinded plasma CoQ10 samples. The authors state that the company had no role in data interpretation or manuscript preparation.

Study snapshot

DesignDouble-blind randomized placebo-controlled independent-group trial.
ModelHealthy recreationally active adult males.
Sample54 participants.
InterventionUbiquinol 300 mg/day versus placebo.
Duration6 weeks.
EndpointsPlasma CoQ10; Skeletal-muscle mitochondrial respiratory coupling / inverse respiratory control ratio; ANT1+2 and UCP3 protein abundance; Severe-intensity exercise tolerance; End-exercise VO2 and VO2 slow-component kinetics

What the study showed, in plain terms

This 2026 randomized trial gave 54 healthy recreationally active men 300 mg/day of ubiquinol or placebo for six weeks and combined blood testing, skeletal-muscle mitochondrial measurements and severe-intensity exercise testing.

Ubiquinol clearly raised plasma CoQ10. It also changed the inverse respiratory control ratio in a direction interpreted as better oxidative-phosphorylation coupling efficiency: the ubiquinol group moved from 0.073 ± 0.039 to 0.044 ± 0.019, while placebo moved from 0.064 ± 0.034 to 0.072 ± 0.026 (between-group effect p<0.05).

That mitochondrial signal did not translate into better exercise performance. End-exercise VO2, VO2 slow-component measures and time-to-exhaustion did not differ between groups. ANT1+2 and UCP3 protein abundance also did not change significantly. The key lesson is that a measurable mitochondrial change is not automatically an ergogenic effect.

Key findings

  • Plasma CoQ10 increased after 300 mg/day ubiquinol for six weeks.
  • Inverse respiratory control ratio improved with ubiquinol: 0.073 ± 0.039 to 0.044 ± 0.019, versus placebo 0.064 ± 0.034 to 0.072 ± 0.026; p<0.05 for the treatment effect.
  • ANT1+2 and UCP3 protein abundance did not significantly differ after supplementation (p>0.05).
  • End-exercise VO2, VO2 kinetics/slow-component measures and severe-intensity exercise tolerance did not significantly improve versus placebo (p>0.05).
  • Biochemical/mitochondrial responsiveness therefore did not produce a demonstrable performance benefit in this healthy active population.

What this study can and cannot tell us

  • Healthy recreationally active men only; results do not establish effects in women, older adults, clinical populations or elite athletes.
  • Six-week duration is adequate for short-term physiology but not long-term performance or clinical outcomes.
  • The mitochondrial coupling endpoint is mechanistic and should not be described as proof of more energy, better endurance or longer lifespan.
  • Kaneka Pharma Europe match-funded the research and performed blinded plasma-CoQ10 analyses; this commercial connection should remain visible alongside the findings.

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Dr. Khaled Mahmoud, MBBChCritical Care Medicine, Longevity Science & Editorial Direction Dr. Amr Yasser, PhDCardiometabolic, Musculoskeletal, Gut & Bioavailability Dr. Abdulla Mostafa, PhDCellular Senescence, Neurological, Mitochondrial & Brain-Ageing Biology