Mitochondrial Influence on Performance Fatigability: Considering Sex Variability
Bibliographic record
Abstract
OBJECTIVE: Existing literature indicates that females generally demonstrate higher fatigue resistance than males during isometric contractions. However, when it comes to single-limb dynamic exercises, the intricate interplay between performance fatigability (PF), cardiovascular responses, and muscle metabolism in relation to sex differences remains underexplored. PURPOSE: This study investigates how sex affects the relationship between muscle oxidative characteristics and the development of PF during dynamic single-leg exercise. METHODS: Twenty-four young healthy participants (12 males vs 12 females) performed a constant-load single-leg knee extension task (85% peak power output; 60 rpm) to exhaustion (TTE). Neuromuscular assessments via transcranial magnetic and peripheral stimulations were conducted before and after exercise to evaluate central and peripheral factors of PF. Vastus lateralis muscle biopsies were obtained for mitochondrial respiration and immunohistochemistry analyses. RESULTS: Participants performed similar total work (28 ± 7 vs 27 ± 14 kJ, P = 0.81) and TTE (371 ± 139 vs 377 ± 158 s, P = 0.98); after the TTE, females' maximal isometric voluntary contraction (MVIC: -36% ± 13% vs -24% ± 9%, P = 0.006) and resting twitch (RT; -65% ± 9% vs -40% ± 24%, P = 0.004) force declined less. No differences were observed in supraspinal neuromuscular factors ( P > 0.05). During exercise, the cardiovascular responses differed between sexes. Although fiber type composition was similar (type I: 47% ± 13% vs 56% ± 14%, P = 0.11), males had lower mitochondrial net oxidative capacity (61 ± 30 vs 89 ± 37, P = 0.049) and higher Complex II contribution to maximal respiration (CII; 59% ± 8% vs 48% ± 6%, P < 0.001), which correlated with the decline in MVIC ( r = -0.74, P < 0.001) and RT ( r = -0.60, P = 0.002). CONCLUSIONS: Females display greater resistance to PF during dynamic contractions, likely due to their superior mitochondrial efficiency and lower dependence on mitochondrial CII activity.
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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 | 0.001 | 0.002 |
| 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) | 0.003 | 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".