Effect Of Fortetropin® Ingestion On Muscle Size And Circulating Myostatin During Disuse Atrophy
Bibliographic record
Abstract
Fortetropin® (FOR), from fertilized egg yolks, supplementation has been shown to reduce circulating myostatin, which may affect muscle growth. In addition, FOR ingestion prevented disuse-induced muscle atrophy in canines. However, the effect of FOR supplementation on human skeletal muscle adaptation during muscle disuse is unknown. PURPOSE: To determine the effect of FOR supplementation on muscle size, strength, and circulating myostatin in young men during 2-wk of single-leg immobilization and recovery. METHODS: 24 healthy young men (22 ± 2 yrs) were randomly allocated to either FOR supplement (FOR-SUPP, n = 12) group consuming 19.8 g/d of FOR or placebo (PLA-SUPP, n = 12) group for 6-wk (2-wk run-in, 2-wk single-leg immobilization, and 2-wk recovery). Participants wore a knee brace on a randomly selected leg during the immobilization phase. Blood samples were collected at days 1 and 42 to measure plasma myostatin. Dual-energy X-ray absorptiometry, ultrasonography, muscle biopsies, and isometric knee-extensor torque test were performed prior to and following each phase (days 1, 14, 28, and 42) to measure immobilized-leg lean mass (LM), vastus lateralis cross-sectional area (CSA), the percentage of myostatin-positive satellite cell (MSTN+/PAX7+), and muscular strength. RESULTS: Circulating myostatin was increased on day 42 compared to day 1 in PLA-SUPP (4221 ± 541 pg/mL to 6721 ± 864 pg/mL, P < 0.05) but not in FOR-SUPP (5487 ± 489 pg/mL to 5382 ± 781 pg/mL, P > 0.05). vastus lateralis CSA declined from 28 ± 1 cm2 on day 1 to 26 ± 1 cm2 after the immobilization phase (day 28) (P < 0.05), and immobilized-leg LM decreased from 10.8 ± 1.4 kg on day 1 to 10.6 ± 1.4 kg at day 28 (P < 0.05), with no difference between groups. MSTN+/PAX7+ satellite cells associated with type II fibers increased from 35 ± 5% on day 1 to 55 ± 5 % on day 28 (P < 0.05), and isometric strength decreased from 160 ± 10 Nm on day 1 to 129 ± 9 Nm on day 28 (P < 0.001), with no difference between groups. The increased MSTN+/PAX7+ and decreased isometric strength were not different from pre-immobilization after 2 weeks of recovery. Neither vastus lateralis CSA nor immobilized-leg LM recovered (no difference between groups). CONCLUSIONS: FOR ingestion prevented the rise in circulating myostatin but not disuse-induced muscle atrophy in young men.
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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) | 0.001 | 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 | 0.001 | 0.001 |
| 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".