Despite Menstrual Phase Differences in Respiration, Blood Lactate, and Muscle Deoxygenation, Exercise Performance is Unchanged
Bibliographic record
Abstract
PURPOSE: Fluctuations of ovarian hormones over the menstrual cycle result in changes in cardiorespiratory and metabolic responses that may affect exercise performance. The purpose of this study is to evaluate respiration, muscle deoxygenation (Δ%[HHb]) and arterialised blood lactate [La-] throughout incremental (RAMP) and constant load exercise performance (EP) during follicular (FOL) and luteal (LUT) phases. METHODS: Ten eumenorrheic females (22 yrs ± 1.4; 167 ± 7 cm; 64 ± 8 kg) completed RAMP (20 W/min) and EP (@ 101% VO2max) to limit of tolerance during both FOL and LUT phases. Breath-by-breath measures of gas exchange and vastus lateralis muscle deoxygenation were recorded throughout. RESULTS: RAMP: FOL and LUT maximal oxygen uptake (VO2max) (FOL: 2.36 ± 0.4 L⋅min-1; LUT: 2.36 ± 0.4 L⋅min-1), ventilation (VE) (FOL: 53.2 ± 25 L⋅min-1; LUT: 55.1 ± 25 L⋅min-1), and %ΔHHb (FOL: 60 ± 3%; LUT: 57 ± 3%) were unchanged (p>0.05). However, %ΔHHb/%ΔVO2 was 65% lower in LUT compared to FOL below lactate threshold (GET) (p<0.05). PETCO2 values were lower in LUT compared to FOL (FOL: 37 ± 2 mmHg; LUT: 36 ± 3mmHg) (p<0.01), whereas PETO2 values remained unchanged (FOL: 105 ± 6 mmHg; LUT: 107 ± 6 mmHg) (p>0.05).EP: VE (FOL: 83 ± 19 L⋅min-1; LUT: 89 ± 17 L⋅min-1) and PETO2 (FOL: 115 ± 4 mmHg; LUT: 118 ± 4 mmHg) were greater in LUT compared to FOL (p<0.05), without changes in breathing frequency (FOL: 32 ± 4 L⋅min-1; LUT: 35 ± 5 L⋅min-1) (p>0.05). No differences in %HHb were observed between LUT and FOL (FOL: 83 ± 21%; LUT: 85 ± 21%); however, %ΔHHb/%ΔVO2 was 18% lower during the kinetic phase of the EP in LUT compared to FOL (p<0.05). Post-EP [La-] were lower in LUT compared to FOL (FOL: 12.9 ± 2.5 mmol⋅L -1; LUT: 11.7 ± 1.7 mmol⋅L -1) (p<0.05). No performance differences were observed between FOL and LUT for RAMP peak power (FOL: 218 ± 35 W; LUT: 221 ± 29 W) or EP endurance (FOL: 99 ± 20 s; LUT: 96 ± 15 s) (p>0.05). CONCLUSION: During RAMP exercise, there was a greater reliance on muscle deoxygenation at sub-GET work rates in FOL compared to LUT. During EP, the LUT phase showed higher VE, lower Post-EP [La-], and lower muscle deoxygenation during the kinetic portion of the step exercise, suggesting increased ventilatory buffering compared to FOL. Despite the different physiological responses between menstrual phases, short duration exercise performance is preserved.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".