# Oral Contraceptive Use Influences On-Kinetic Adaptations to Sprint Interval Training in Recreationally-Active Women

PMID: 32595523
Journal: Frontiers in Physiology
Published: 2020 Jun 12
Authors: Schaumberg MA, Stanley J, Jenkins DG, Hume EA, Janse de Jonge XAK, Emmerton LM, Skinner TL

## Question

Does oral contraceptive use influence pulmonary, cardiovascular, and muscle oxygenation adaptations to sprint interval training in recreationally active women?

## Summary

Recreationally active women completed 4 weeks of supervised cycle sprint interval training. Training improved time to fatigue in both oral-contraceptive users and naturally cycling women, but physiological adaptations differed by hormonal status: VO2 kinetics improved mainly in naturally cycling women, while muscle oxygenation kinetics improved mainly in oral-contraceptive users.

## Population

- 47 healthy recreationally active women grouped by oral contraceptive use.
- Sample size: 47
- Sex: Female
- Fitness level: Recreationally active
- Health status: Healthy

## Methodology

- Non-randomized comparative intervention grouped by oral contraceptive status
- 4 weeks
- Laboratory-based supervised cycle sprint interval training
- Controlled study design.

## Protocol

- Cycle SIT.
- Modality: Wattbike cycling.
- Work intervals: 1 min.
- Recovery: 2 min passive recovery.
- Sets or repetitions: 10 intervals.
- Intensity: 100-120% peak power output; maximal sustainable effort.
- Session duration: About 30 min interval block.
- Frequency: 3 sessions/week.
- Program length: 4 weeks.
- Progression: No formal progression described.
- Natural menstrual-cycle group.
- Modality: Same Wattbike SIT protocol.
- Work intervals: 1 min.
- Recovery: 2 min passive recovery.
- Sets or repetitions: 10 intervals.
- Intensity: 100-120% peak power output; maximal sustainable effort.
- Session duration: About 30 min interval block.
- Frequency: 3 sessions/week.
- Program length: 4 weeks.
- Progression: No formal progression described.

## Outcomes

### Time to fatigue
Status: improved
Both groups improved exercise tolerance.

Time to fatigue increased in both groups, p<0.001; no clear between-group difference.

### VO2 kinetics
Status: mixed
VO2 kinetics improved in naturally cycling women but not oral-contraceptive users.

MC improved at moderate p=0.021 and high p=0.015; group x time moderate p=0.020.

### TSI kinetics
Status: mixed
Muscle tissue saturation kinetics improved in oral-contraceptive users but not naturally cycling women.

OC improved at moderate and high intensity, both p<0.001; group x time moderate p=0.001, high p<0.001.

## Practical Insights

- A 1:2 work-rest cycle SIT format improved performance in active women.
- Adaptation mechanisms may vary by oral contraceptive status.
- Mechanistic physiology findings should not be simplified into one-size-fits-all claims.

## Limitations

- Groups were not randomized by contraceptive status.
- Short 4-week intervention.
- Mechanistic outcomes may not map directly to user-facing benefits.
- Safety and adherence reporting was limited.
- Female hormonal subgroup findings limit generalizability.

## Safety And Adherence

- Training was supervised and HR/RPE/power were recorded.
- Adverse events and injuries were not clearly reported.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/32595523/) (pubmed)
- [DOI](https://doi.org/10.3389/fphys.2020.00629) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7303366/) (full text)

## Agent Guidance

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