# Global Proteomics Reveals Distinct Muscle Adaptations to Menstrual Cycle Phase-Based Sprint Interval Training in Endurance-Trained Females

PMID: 40818533
Journal: Molecular & cellular proteomics : MCP
Published: 2025 Oct
Authors: Kissow J, Jacobsen KJ, Jessen S, Thomsen LB, Quesada JP, Bangsbo J, Deshmukh AS, Hostrup M

## Question

Does high-frequency sprint interval training concentrated in the follicular versus luteal menstrual-cycle phase produce different skeletal muscle proteome and performance adaptations in endurance-trained females?

## Summary

In endurance-trained women with regular menstrual cycles, eight all-out cycling sprint sessions over one menstrual cycle produced different muscle-protein and performance responses depending on when most sessions were scheduled. Follicular-phase-focused training maintained VO2max and improved exercise capacity, while luteal-phase-focused training reduced VO2max and suppressed mitochondrial pathways.

## Population

- Healthy endurance-trained eumenorrheic females not using hormonal contraceptives
- Sample size: 25
- Age: 18-45 years inclusion
- Sex: Female
- Fitness level: Endurance-trained; at least 3 sessions/week and VO2max about 50 ml/kg/min or higher
- Health status: Healthy regular menstrual cycles; no chronic disease, injury, smoking, anovulatory cycles, or pregnancy

## Methodology

- Longitudinal randomized parallel-group training study
- One menstrual cycle, about 28 +/- 2 days
- University exercise physiology laboratory with supervised spinning-bike SIT and muscle biopsy/proteomics
- Randomized and controlled study design.

## Protocol

- Phase-based cycling SIT.
- Modality: Spinning bike.
- Work intervals: 30 seconds all-out.
- Recovery: 3 minutes rest.
- Sets or repetitions: 6.
- Intensity: All-out.
- Session duration: About 20.5 minutes including 5-minute warm-up and intervals/rests.
- Frequency: 8 sessions over one menstrual cycle, concentrated 6 in one phase and 2 in the other.
- Program length: One menstrual cycle.
- Progression: Timing distribution by cycle phase rather than load progression.
- Opposite phase-based SIT timing.
- Modality: Same spinning-bike SIT.
- Work intervals: 30 seconds all-out.
- Recovery: 3 minutes rest.
- Sets or repetitions: 6.
- Intensity: All-out.
- Session duration: Same.
- Frequency: Same total dose with high-frequency sessions in opposite cycle phase.
- Program length: One menstrual cycle.
- Progression: Same dose, different timing.

## Outcomes

### VO2max
Status: mixed
Follicular-focused training maintained VO2max, while luteal-focused training reduced it.

Group x time p=0.027; LB -117 ml/min, 95% CI -204 to -29, p=0.047; FB p=0.364.

### Exercise capacity
Status: improved
Only the follicular-focused group improved ramp exercise capacity.

FB 95% CI 0.3 to 18 W, p=0.043.

### Mitochondrial pathways
Status: worse/safety concern
Luteal-focused SIT suppressed mitochondrial electron transport and TCA-cycle pathways.

Gene set enrichment and mitochondrial-complex protein analyses showed consistent decreases in LB.

### Tissue remodeling
Status: improved
Follicular-focused SIT produced stronger extracellular matrix remodeling signals.

Greater increase in extracellular matrix organization proteins in FB.

## Practical Insights

- Menstrual-cycle phase may be a relevant internal personalization variable for advanced trained women, especially for dense sprint blocks.
- App copy should avoid rigid cycle-based rules because this is one short trained-athlete study.
- Workout generation can mark all-out SIT blocks as high strain and avoid stacking them without recovery context.

## Limitations

- Small final sample.
- One menstrual cycle only.
- All participants were trained eumenorrheic females not using hormonal contraceptives.
- Usual training continued.
- Adverse events were not clearly reported.

## Safety And Adherence

- Adverse events were not reported in the reviewed text.
- Participants were screened for health, injury, smoking, cycle regularity, ovulation, luteal phase adequacy, and pregnancy.
- All-out sprint cycling was tested in already trained women.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/40818533/) (pubmed)
- [DOI](https://doi.org/10.1016/j.mcpro.2025.101053) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12538072/) (full text)

## Agent Guidance

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