EFFECTS OF REDUCED FREE FATTY ACID AVAILABILITY ON SKELETAL MUSCLE PDH ACTIVATION DURING AEROBIC EXERCISE
Bibliographic record
Abstract
Numerous laboratories have examined the effects of increasing fat availability on skeletal muscle carbohydrate metabolism. Few studies have examined the effects of reduced fat availability on skeletal muscle carbohydrate metabolism during exercise. PURPOSE This study investigated the effect of FFA availability on pyruvate dehydrogenase activation (PDHa) and carbohydrate metabolism during moderate aerobic exercise. Muscle metabolites believed to regulate PDHa were also measured. METHODS Eight male subjects cycled for 40 min at 55% VO2 peak on two occasions. During one trial subjects ingested 20 mg/kg bm of the antilipolytic drug nicotinic acid (NA) during the hour before exercise to reduce FFA. Nothing was ingested in the control trial (CON). Blood and expired gas measurements were obtained throughout the trials and muscle biopsy samples were obtained immediately prior to exercise and at 5, 20 and 40 min of exercise. RESULTS Plasma FFA was significantly lower and the respiratory exchange ratio (RER) was increased with NA (0.03–0.05), resulting in a 15% increase in carbohydrate oxidation compared to CON. PDHa increased rapidly in both trials at exercise onset but was 15% higher (P < 0.05) throughout exercise in the NA trial. Despite 15% greater glycogenolysis in the NA trial there was no difference between the trials. Glucose-6-phosphate contents were elevated (P < 0.05) in the NA trial at 30 and 40 min of exercise, but pyruvate and lactate contents were unaffected. NA ingestion reduced (P < 0.05) acetylcarnitine prior to exercise compared to CON. CONCLUSION Data indicates that the reduction of exogenous FFA availability increased the activation of PDHa and carbohydrate oxidation during aerobic exercise in men. The increased activation of PDHa was not explained by changes in muscle pyruvate or the ATP/ADP ratio but may be related to a decrease in the NADH/NAD+ ratio or an epinephrine induced increase in calcium content. Supported by NSERC and CIHR of Canada, and the Gatorade Sports Science Institute.
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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) | 0.001 | 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".