# The effects of L-citrulline supplementation on cerebrovascular function during sprint interval training in taekwondo athletes

PMID: 40474881
Journal: Journal of Exercise Science and Fitness
Published: 2025 Jul
Authors: Li A, Li H, Chen J

## Question

Does short-term L-citrulline supplementation improve cerebrovascular recovery after sprint interval cycling in trained male taekwondo athletes?

## Summary

In a double-blind randomized crossover study, 20 male taekwondo athletes took L-citrulline or placebo for 5 days before a sprint interval cycling session. L-citrulline improved the breath-holding index recovery measure after exercise but did not significantly change sprint power or pulse index.

## Population

- Male taekwondo athletes with provincial-or-higher competition experience
- Sample size: 20
- Age: 25.05 +/- 1.73 years
- Sex: Men only
- Fitness level: Competitive taekwondo athletes with 3-5 years of experience
- Health status: Healthy athletes screened for vascular, metabolic, injury, medication, and supplement contraindications

## Methodology

- Double-blind randomized crossover supplementation trial
- Two 5-day supplementation phases with 2-week washout
- Laboratory cycling and transcranial Doppler testing
- Randomized and controlled study design.

## Protocol

- L-citrulline plus cycle SIT.
- Modality: Cycle ergometer.
- Work intervals: 30 seconds maximal sprint.
- Recovery: 3 minutes active recovery without resistance.
- Sets or repetitions: 4 sprints.
- Intensity: Maximal pedaling against 0.075 kp/kg body weight.
- Session duration: 5-minute warm-up plus four sprints and recoveries.
- Frequency: Single test session per supplementation phase.
- Program length: 5-day supplementation phase before test.
- Progression: No exercise progression; L-citrulline 8.8 g/day for 5 days.
- Placebo plus cycle SIT.
- Modality: Cycle ergometer.
- Work intervals: 30 seconds maximal sprint.
- Recovery: 3 minutes active recovery without resistance.
- Sets or repetitions: 4 sprints.
- Intensity: Maximal pedaling against 0.075 kp/kg body weight.
- Session duration: 5-minute warm-up plus four sprints and recoveries.
- Frequency: Single test session per supplementation phase.
- Program length: 5-day placebo phase before test.
- Progression: No exercise progression; maltodextrin placebo with same dosing schedule.

## Outcomes

### BHI recovery
Status: improved
L-citrulline improved delta BHI versus placebo after SIT.

Delta BHI 0.07 +/- 0.22 with L-citrulline vs -0.18 +/- 0.46 placebo; F=5.09, p=0.037, partial eta squared=0.22.

### Average power
Status: no clear change
Average sprint power was not significantly different between conditions.

F=1.27, p=0.275, partial eta squared=0.07.

### Pulse index
Status: no clear change
Pulse index change did not significantly differ between conditions.

F=0.19, p=0.669, partial eta squared=0.01.

## Practical Insights

- This paper supports a narrow recovery-marker claim, not a performance claim.
- The sprint protocol is reproducible but equipment-based and athlete-specific.
- Consumer supplement messaging should note the small male-athlete crossover design.

## Limitations

- Small sample size.
- Male taekwondo athletes only.
- Short-term supplement and acute exercise design.
- Surrogate cerebrovascular outcomes.
- Diet, sleep, and stress were not fully controlled.

## Safety And Adherence

- No adverse-event results were reported in the extracted text.
- Participants were medically screened and supplement allergies were exclusionary.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/40474881/) (pubmed)
- [DOI](https://doi.org/10.1016/j.jesf.2025.04.004) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12137154/) (full text)

## Agent Guidance

Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.