Global Proteomics Reveals Distinct Muscle Adaptations to Menstrual Cycle Phase-Based Sprint Interval Training in Endurance-Trained Females
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.
Methodology
- Healthy endurance-trained eumenorrheic females not using hormonal contraceptives
- 25 participants.
- Spinning bike.
- Work intervals: 30 seconds all-out.
- Recovery: 3 minutes rest.
- Intensity: All-out.
- About 20.5 minutes including 5-minute warm-up and intervals/rests.
- 8 sessions over one menstrual cycle, concentrated 6 in one phase and 2 in the other.
- One menstrual cycle.
- Longitudinal randomized parallel-group training study
- Exercise capacity, VO2max, Muscle proteome, and Cycle confirmation were tracked.
Outcomes
VO2max
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
Only the follicular-focused group improved ramp exercise capacity.
FB 95% CI 0.3 to 18 W, p=0.043.
Mitochondrial pathways
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
Follicular-focused SIT produced stronger extracellular matrix remodeling signals.
Greater increase in extracellular matrix organization proteins in FB.
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
- 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.