Biological sex does not impact intrinsic mitochondrial respiration supported by complexes I and II in human skeletal muscle
Bibliographic record
Abstract
The effect of biological sex on rates of skeletal muscle mitochondrial respiration supported by creatine-dependent phosphate shuttling was previously unknown. The aim of this investigation was to test the hypothesis that females and males matched for peak oxygen uptake normalized to fat-free mass would not exhibit differences in rates of mass-specific and intrinsic mitochondrial respiration in the presence or absence of creatine. Rates of mass-specific and intrinsic complex I (pyruvate and malate)- and complex I+II-supported, adenosine diphosphate (ADP)-stimulated mitochondrial respiration in the presence and absence of 20 mM creatine were measured via high-resolution respirometry. Total, intermyofibrillar and subsarcolemmal mitochondrial volume density were analysed using transmission electron microscopy. Rates of intrinsic mitochondrial respiration were obtained by normalizing mass-specific respiration rates to total mitochondrial volume density and total electron transport chain subunit protein content. Overall, there was no effect of sex on rates of mass-specific or intrinsic mitochondrial respiration in the presence or absence of creatine. There was also no effect of sex on total, intermyofibrillar and subsarcolemmal mitochondrial volume density or electron transport chain subunit protein content. Our data demonstrate an overall lack of sex-based differences in rates of intrinsic complex I- and complex I+II-supported, ADP-stimulated mitochondrial respiration in the presence or absence of creatine in females and males matched for aerobic fitness. Thus, biological sex per se does not appear to modulate intrinsic skeletal muscle mitochondrial respiration in healthy young adults.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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) | 0.000 | 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 teacher head, 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".