# Effects of an 8-week high intensity interval training (HIIT) and ashwagandha supplementation on aerobic capacity, muscle oxygenation and haematological parameters in healthy men

PMID: 40657001
Journal: Biology of Sport
Published: 2025 Jul
Authors: Ewa J, Klusiewicz A, Rębiś K, Długołęcka B, Charmas M, Cieśliński I

## Question

Does ashwagandha supplementation improve aerobic capacity, muscle oxygenation, or hematological responses during an 8-week rowing HIIT program in healthy male non-athletes?

## Summary

Healthy young men did 8 weeks of supervised rowing HIIT while taking ashwagandha or placebo. Training improved rowing test performance and absolute aerobic capacity markers, but ashwagandha did not provide extra benefits for aerobic capacity or resting blood measures; muscle oxygenation findings were mixed and favored placebo on some indices.

## Population

- Healthy male physical education students/non-athletes
- Sample size: 33
- Age: Young adult students; exact mean by final analysis group not extracted
- Sex: Men only
- Fitness level: Healthy non-athletes completing maximal rowing tests
- Health status: Healthy; chronic disease, recent injury, substance use, and relevant medications/supplements excluded

## Methodology

- Randomized double-blind placebo-controlled supplementation trial with supervised rowing HIIT in both groups
- 8 weeks
- University exercise laboratory/training setting
- Randomized and controlled study design.

## Protocol

- Ashwagandha plus rowing HIIT.
- Modality: Rowing ergometer.
- Work intervals: 1.5 minutes.
- Recovery: 1.5 minutes at 70 W.
- Sets or repetitions: 5-7 intervals.
- Intensity: 75-95% maximal aerobic power by study week.
- Session duration: About 15-21 minutes of interval/recovery work.
- Frequency: 3 sessions/week.
- Program length: 8 weeks.
- Progression: Progressed interval intensity and count; ashwagandha 600 mg/day.
- Placebo plus rowing HIIT.
- Modality: Rowing ergometer.
- Work intervals: 1.5 minutes.
- Recovery: 1.5 minutes at 70 W.
- Sets or repetitions: 5-7 intervals.
- Intensity: 75-95% maximal aerobic power by study week.
- Session duration: About 15-21 minutes of interval/recovery work.
- Frequency: 3 sessions/week.
- Program length: 8 weeks.
- Progression: Same HIIT progression with placebo capsules.

## Outcomes

### Aerobic capacity
Status: improved
Both groups improved test time, maximal aerobic power, anaerobic threshold power, and absolute VO2max, with no added ashwagandha effect.

Significant time effects for test time, MAP, PAT4, and absolute VO2max; no significant group or interaction effects.

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

Reported p=0.15.

### Muscle oxygenation
Status: mixed
Some SmO2 indices improved in placebo but not ashwagandha, with no clear supplement advantage.

Time-by-group effects were reported for SmO2Min and delta SmO2; post hoc improvements occurred in placebo.

### Hematology
Status: no clear change
Resting hematological parameters did not show meaningful supplement or training changes.

No significant group or interaction effects were reported.

## Practical Insights

- The training program, not the ashwagandha supplement, accounts for the observed performance-related improvements.
- Relative-power rowing HIIT is reproducible but requires equipment and testing.
- Muscle oxygenation findings should not be converted into consumer claims without replication.

## Limitations

- Small sample of healthy young men.
- No non-exercise control group.
- Technical exclusions for muscle oxygenation.
- Relative VO2max did not improve significantly.
- Adverse-event and session adherence details were not reported.

## Safety And Adherence

- Three participants dropped out for personal reasons.
- Five participants were excluded from analysis because of technical problems measuring muscle oxygenation.
- No adverse-event outcomes were reported in the extracted article.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/40657001/) (pubmed)
- [DOI](https://doi.org/10.5114/biolsport.2025.147453) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12244407/) (full text)

## Agent Guidance

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