Increased capillary density in skeletal muscle is not associated with impaired insulin sensitivity induced by bed rest in healthy young men
Bibliographic record
Abstract
Physical inactivity alters glucose homeostasis in skeletal muscle, potentially developing into overt metabolic disease. The present study sought to investigate the role of skeletal muscle capillarization in glucose tolerance and insulin sensitivity (IS) using a classic human model of physical inactivity. Thirteen healthy males (age = 23 ± 2 years) underwent 4 days of full-time supervised and diet-controlled bed rest. Oral glucose tolerance test, indices of IS (quantitative insulin sensitivity check index (QUICKI), Matsuda index), as well as skeletal muscle biopsies with measurement of fiber type distribution, fiber cross-sectional area (FCSA), capillary-to-fiber ratio (C/F ratio), and capillary density (CD) were assessed prior to and after bed rest. Body weight and composition were unaltered by bed rest. Fasting glucose/insulin ratio (G0/I0 ratio) (−25%, P = 0.016), QUICKI (−7%, P = 0.023), and Matsuda index (−24%, P = 0.003) diminished with bed rest. Skeletal muscle FCSA decreased (−737.4 ± 763.2 μm−2 (−12%), P = 0.005) while C/F ratio was preserved, resulting in augmented CD (+93.9 ± 91.5 capillaries·mm−2 (+37%), P = 0.003) with bed rest. No association was detected between changes in skeletal muscle variables and metabolic outcomes. Independently of bed rest-induced effects, a positive linear relationship was detected between C/F ratio and G0/I0 ratio (β = 17.09, P = 0.021). In conclusion, impaired glucose homeostasis with bed rest is not prevented nor associated with enhanced skeletal muscle capillarization in healthy individuals.
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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 | 0.000 |
| 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".