# Molecular, Systemic, and Physiological Adaptations to High-Intensity Interval Training in Flatwater Kayak Athletes

PMID: 41441435
Journal: Biology
Published: 2025
Authors: Papandreou A, Tzanis G, Moustogiannis A, Zevolis E, Zacharogiannis E, Maridaki M, Nanas S, Koutsilieris M, Philippou A

## Question

What physiological, systemic, and molecular adaptations occur after eight weeks of kayak-specific HIIT in flatwater kayak athletes?

## Summary

In a very small group of national-level male kayak athletes, eight weeks of supervised kayak-ergometer HIIT improved 200 m and 1000 m performance and changed several molecular markers, but VO2max did not significantly change.

## Population

- National-level male flatwater kayak athletes.
- Sample size: 6
- Age: 18 +/- 4 years
- Sex: Male
- Fitness level: National-level athletes
- Health status: Healthy athletes after exclusions

## Methodology

- Uncontrolled pre-post intervention
- 8 weeks after a 6-week detraining/transition phase
- Kayak ergometer simulator training

## Protocol

- Kayak 30/60 HIIT.
- Modality: Kayak ergometer.
- Work intervals: 30 s at 120% VO2max.
- Recovery: 60 s passive recovery.
- Sets or repetitions: 8.
- Intensity: 120% VO2max.
- Session duration: Interval block about 11.5 min; warm-up/cool-down not reported.
- Frequency: 3 sessions/week.
- Program length: 8 weeks.

## Outcomes

### Performance
Status: improved
200 m and 1000 m times improved.

1000 m p=0.0027; 200 m p=0.0004.

### VO2max
Status: no clear change
VO2max did not significantly change.

p=0.593.

### Body fat
Status: improved
Body fat percentage decreased.

11.80% to 10.59%, p=0.002.

## Practical Insights

- Sport-specific 30/60 intervals may improve race performance in trained athletes.
- Do not equate performance gains with VO2max gains.

## Limitations

- Very small sample
- No control group
- Male athlete-only cohort
- Molecular directions partly unclear for inflammation
- Simulator-specific testing

## Safety And Adherence

- No adverse events were reported.
- Eight athletes enrolled and six completed; reasons for non-completion were not reported.
- Training was coach-supervised, sessions were spaced with at least 24 h between sessions, and biopsy procedures used local anesthesia with no adverse biopsy events reported.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/41441435/) (pubmed)
- [DOI](https://doi.org/10.3390/biology14121529) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12736612/) (full text)

## Agent Guidance

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