# High-intensity interval training improves the reactive strength index and motor ability of youth football players

PMID: 41622262
Journal: BMC sports science, medicine & rehabilitation
Published: 2026 Feb 2
Authors: Kızılca S, Kahraman MZ, Okut S, Arslan E, Bilici ÖF, Çelik İ, İşlen T, Altıntaş S, Bilici MF

## Question

Does a 4-week running-based HIIT block improve reactive strength index and motor abilities in 11-13-year-old male football players compared with regular football training alone?

## Summary

In 20 male youth football players aged 11-13, adding an 8-minute running HIIT segment three times per week for 4 weeks improved within-group performance measures and group-by-time interactions for RSI, sprinting, back strength, agility, and countermovement jump. Post-test between-group differences were not significant, and all participants completed the protocol without adverse events.

## Population

- Male youth football players aged 11-13 years
- Sample size: 20
- Age: 12.15 +/- 0.81 years overall
- Sex: Male
- Fitness level: Youth football academy players
- Health status: No reported conditions affecting high-intensity exercise

## Methodology

- Randomized pretest-posttest controlled trial
- 4 weeks
- Football academy training and natural grass field testing
- Randomized and controlled study design.

## Protocol

- Running-based youth football HIIT.
- Modality: Running.
- Work intervals: 15 seconds.
- Recovery: 30 seconds; 3 minutes between sets.
- Sets or repetitions: 2 sets of 6 reps.
- Intensity: 80-90% target HR progression.
- Session duration: 8-minute HIIT block.
- Frequency: 3 days/week.
- Program length: 4 weeks.
- Progression: Intensity increased from 80% to 90%.
- Regular football training.
- Modality: Football practice.
- Intensity: Low-to-moderate technical-tactical segment retained.
- Session duration: 75-90 minutes.
- Frequency: 3 days/week.
- Program length: 4 weeks.
- Progression: Routine training.

## Outcomes

### RSI
Status: improved
RSI improved with significant group-by-time interaction favoring HIIT.

p<0.05; large effect sizes reported

### sprint and COD
Status: improved
Sprint and change-of-direction outcomes improved within the HIIT group and had significant group-by-time interactions.

p<0.05; partial eta squared 0.20-0.30 for interactions

### between-group post-test
Status: no clear change
Despite favorable changes, post-test between-group comparisons were not statistically significant.

Post-test between-group comparisons not significant

### safety
Status: no clear change
No adverse events, injuries, or unintended effects occurred.

## Practical Insights

- A short 8-minute HIIT block can replace, not add to, lower-intensity practice work to manage total load.
- For performance goals, 15-second efforts with 30-second recoveries are useful and easy to express in an app.
- Youth-related content must keep supervision and population limits explicit.

## Limitations

- Small sample
- Male youth football players only
- No follow-up
- Between-group post-test differences not significant
- No quantitative total-load monitoring beyond duration

## Safety And Adherence

- No adverse events, injuries, or unintended effects were observed in either group.
- All sessions included standardized warm-up and cooldown routines under certified supervision.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/41622262/) (pubmed)
- [DOI](https://doi.org/10.1186/s13102-026-01560-9) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13001278/) (full text)

## Agent Guidance

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