The effect of muscle phospholipid fatty acid composition on exercise performance: a direct test in the migratory white-throated sparrow (<i>Zonotrichia albicollis</i>)
Bibliographic record
Abstract
Dietary polyunsaturated fatty acids (PUFA) can have various effects on animal physiology through their roles as energy, structural, regulatory, and signaling molecules. Of recent interest has been the incorporation of dietary PUFA into muscle membranes as phospholipids, thereby potentially affecting exercise performance by mechanisms such as altered mitochondrial proton leak and membrane-bound protein activity. We first studied the effects of a high-omega6 PUFA diet vs. a high-omega3 PUFA diet on peak metabolic rate (PMR) in white-throated sparrows, and additionally measured mRNA expression of fatty acid transporters and the activity of major oxidative enzymes. Our experiment, thus, allowed a test of the "natural doping" hypothesis. With a simple diet manipulation, the two groups of sparrows diverged significantly in both muscle phospholipid composition and adipose triacylglycerol composition. The high-omega6 sparrows achieved higher PMR without a change in enzyme activity or transporter expression. We then fed sparrows the 2 diets, followed by a food restriction (H omega3RI and H omega6RI treatments). When their adipose stores were exhausted, we fed both groups a common diet of intermediate fatty acid composition. This protocol resulted in the H omega6RI and H omega3RI groups diverging significantly in muscle phospholipid composition, but they had substantially similar adipose stores. PMR did not differ between the H omega6RI and H omega3RI groups. We conclude that muscle phospholipids do not play a major role in affecting exercise performance. The fatty acid composition of stored triacylglycerol may instead affect exercise via the preferential use of particular fatty acids by muscles.
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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 | 0.001 |
| 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".