Effects Of Low-load, High-repetition Exercise And Sex On Metabolic Properties Of Skeletal Muscle
Bibliographic record
Abstract
INTRODUCTION: During exercise women are better able to initiate aerobic metabolism and are less reliant on anaerobic energy stores. Whether this metabolic difference persists during resistance exercise remains unknown. PURPOSE: To characterize fuel utilization patterns during a bout of low-load, high-repetition (LL-HR) resistance exercise and determine whether sex influences the fuel utilization pattern. METHODS: Twenty young, healthy participants (n=10 men and women) were recruited and matched for VO2peak relative to fat-free mass and habitual resistance training. The LL-HR bout consisted of a circuit of chest press, leg extension, lat pulldown, hamstring curl, shoulder press, and leg press for 25-35 repetitions at 30% of 1RM with 30s rest between each exercise and 2 minutes rest between circuits. Muscle biopsies were taken prior to and following exercise and finger prick assessment of blood lactate was taken during the exercise bout. Western blot analysis was completed for assessment of the high-energy phosphate transfer (CK, phosphorylated CK, AMPD2) and glycolytic (GP, PFK, LDH H and M, PDHE1α, PDHK4, MCT 1 and 4, phosphorylated PDHE1α) pathways. Muscle content of creatine, ATP, lactate, Pi, pyruvate, and glycogen were also determined. Muscle fibre type was determined using myosin heavy chain immunofluorescence staining. RESULTS: Women had a higher proportion of type I muscle fibres than men (p=0.007). There were no sex differences in the protein content of any of the enzymes at rest. Men had higher content of muscle glycogen (p=0.001), lactate (p=0.02), ATP (p=0.01), and Pi (p=0.007) than women. Glycogen, ATP, and phosphorylation of CK and PDHE1α decreased in men and women with exercise (p<0.001). Phosphorylation of CK decreased to a greater extent in women (p=0.023) and women tended to use more glycogen (p=0.081) during exercise. Alternatively, creatine increased to a greater extent in men (p=0.026) and men tended to have a greater lactate concentration at the end of the exercise bout (p=0.097). CONCLUSION: Sex differences in fuel metabolism during LLHR resistance exercise exist. While women tend to utilize more glycogen during LLHR, men have a higher muscle lactate content, suggestive of a greater reliance on anaerobic metabolism.
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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) | 0.005 | 0.001 |
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".