Dietary Supplements

Effects of Acute Ecklonia cava Supplementation on Submaximal Cycling and Repeated-Sprint Performance in Trained Cyclists: A Randomised Double-Blind Placebo-Controlled Crossover Trial.

Ali Y, Gurney T, Brouner J, Spendiff O • Nutrients • 2026

PubMed 42943001 DOI 10.3390/nu18203430
TL;DR

Acute ingestion of 263 mg of Ecklonia cava extract produced a modest overall elevation in blood glucose during submaximal cycling, but did not improve repeated-sprint performance or materially alter the other measured physiological responses, so the findings do not support an acute ergogenic effect in experienced male cyclists under the conditions tested.

Key Findings

Results

Blood glucose was higher overall during submaximal cycling after Ecklonia cava (EC) than after placebo.

  • Mean glucose was 4.23 ± 0.23 mmol·L-1 with EC vs. 4.02 ± 0.33 mmol·L-1 with placebo.
  • Mean difference was 0.213 mmol·L-1 (95% CI, 0.046 to 0.379; p = 0.023).
  • Participants ingested 263 mg of EC extract 30 min before 60 min of cycling at 55% of maximum work rate.
Results

The EC-related glucose elevation did not differ across time points during submaximal cycling.

  • The treatment × time interaction for blood glucose was not significant (p = 0.939).
  • The effect was therefore an overall shift rather than a time-specific one.
Results

EC did not affect other physiological responses during submaximal cycling.

  • Blood lactate, heart rate, oxygen uptake and respiratory exchange ratio (RER) were not different between EC and placebo (all p ≥ 0.096).
  • These outcomes were measured during 60 min of cycling at 55% of maximum work rate.
Results

EC did not alter peak power or mean power during repeated maximal sprints.

  • Peak power mean difference was -2.58 W (95% CI, -29.51 to 24.35; p = 0.832).
  • Mean power mean difference was 5.93 W (95% CI, -2.47 to 14.33; p = 0.167).
  • Sprints were three 20 s maximal efforts following the submaximal cycling bout.
Results

EC did not significantly change post-sprint blood glucose or lactate, and no repeated-sprint outcome showed a treatment × time interaction.

  • Post-sprint glucose p = 0.481; post-sprint lactate p = 0.060 (not significant, but closest to threshold).
  • No treatment × time interaction was identified for any repeated-sprint outcome (all p ≥ 0.267).
Conclusions

The study found no evidence of an acute ergogenic effect of EC in experienced male cyclists under the tested conditions.

  • Design: randomised, double-blind, placebo-controlled crossover trial in 12 experienced male cyclists.
  • Outcomes were analysed with linear mixed-effects models including treatment, time, treatment × time, experimental period and allocated sequence.
  • Authors conclude EC did not improve repeated-sprint performance or materially alter other measured physiological responses.

What This Means

This study tested whether a single dose of Ecklonia cava, an edible brown seaweed extract, could help trained male cyclists perform better. Twelve cyclists each took 263 mg of the extract or a placebo 30 minutes before an hour of moderate cycling, followed by three all-out 20-second sprints. The researchers compared blood sugar, blood lactate, heart rate, oxygen use, fuel use (RER), and sprint power between the two conditions. The only clear difference was slightly higher blood glucose with the extract during the moderate cycling (about 0.2 mmol/L higher on average). Heart rate, oxygen use, lactate, fuel use and sprint power (peak and mean) did not meaningfully differ from placebo. The glucose difference was also not tied to any particular time point. This research suggests that a single 263 mg dose of Ecklonia cava does not boost short-term sprint performance in experienced male cyclists. The study was small (12 participants, all male) and tested only one dose and a single acute use, so it cannot say whether other doses, longer supplementation, or other groups of people might respond differently.

Check Your Own Numbers

Upload your bloodwork. We'll cross-reference your results against this study and 4,700 others.

Upload Your Labs

Have a question about this study?

Presence or severity of Hashimoto's thyroiditis does not influence basal calcitonin levels: observations from CROHT biobank.
Journal of endocrinological investigation • 2022

HT patients of all disease stages preserve Ct production as healthy individuals and there is no need for Ct measurements...
Approach to the Patient: Safety of Growth Hormone Replacement in Children and Adolescents.
The Journal of clinical endocrinology and metabolism • 2022

rhGH therapy has been used for more than 3 decades and data are largely reassuring, yet we still have much to learn abou...
Extended Absorption of Liothyronine from Poly-Zinc-Liothyronine: Results from a Phase 1, Double-Blind, Randomized, and Controlled Study in Humans.
Thyroid : official journal of the American Thyroid Association • 2022

PZL possesses the necessary properties to achieve a much improved T3 pharmacokinetic profile, with ~30% lower Cmax that...
Lipoprotein subtypes after testosterone therapy in transmasculine adolescents.
Journal of clinical lipidology • 2022

Testosterone appears to be a major contributor to differences in lipoprotein profiles, a surrogate for cardiovascular di...
Long-term testosterone undecanoate treatment in the elderly testosterone deficient male: An observational cohort study.
Andrology • 2022

Long-acting testosterone undecanoate treatment in elderly testosterone-deficient patients required more frequent dose ad...
Society for Endocrinology guidelines for testosterone replacement therapy in male hypogonadism.
Clinical endocrinology • 2022

The Society for Endocrinology commissioned a multidisciplinary guideline to provide all care providers with a comprehens...

Citation

Ali Y, Gurney T, Brouner J, Spendiff O. (2026). Effects of Acute Ecklonia cava Supplementation on Submaximal Cycling and Repeated-Sprint Performance in Trained Cyclists: A Randomised Double-Blind Placebo-Controlled Crossover Trial.. Nutrients. https://doi.org/10.3390/nu18203430