High-intensity Interval Training Increases The Rate Of Mitochondrial Fatty Acid Oxidation in skeletal muscle
Bibliographic record
Abstract
PURPOSE: High-intensity interval training (HIIT) can increase mitochondrial volume and density and induce an increase in oxidative capacity in skeletal muscle. However, it is unclear whether HIIT alters the intrinsic capacity of mitochondria to oxidize substrates. It is known that there are subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondria in skeletal muscle. We hypothesized that HIIT would increase rates of fatty acid and pyruvate oxidation in IMF mitochondria, because IMF mitochondria distribute between the myofibrils and that we predicted exercise training would stimulate IMF mitochondria to a greater extent. To clarify this hypothesis, we examined effects of HIIT on contents of mitochondrial substrate transporter protein, mitochondrial enzyme activities and substrates oxidation rates in isolated SS and IMF mitochondria in skeletal muscle. METHODS: Sprague-Dawley male rats were divided into control or HIIT groups, and the HIIT group performed 10 bouts of 1 min high-intensity treadmill running (30-55 m/min) with 2 min rest 5 days/wk for 4 wk. Thereafter hindlimb muscle was harvested 48 hr after last bout of training. The analyses were carried out at whole muscle level or isolated mitochondrial level. RESULTS: HIIT increased substrates transporters, namely fatty acid translocase (FAT)/CD36, glucose transporter 4 (GLUT4) and monocarboxylate transporter (MCT) 1, in whole muscle. Also mitochondrial markers, citrate synthase activity and cytochrome c oxidase subunit IV protein, were increased with HIIT. These results suggest that the capacity of substrate transport and mitochondrial density were improved in whole muscle. In isolated mitochondria, HIIT increased the rate of fatty acid oxidation in both SS and IMF mitochondria in red muscle and the increase in mitochondrial palmitate oxidation was accompanied with concomitant increase in,-hydroxyacyl-CoA dehydrogenase activity. However, pyruvate oxidation was not altered in SS and IMF mitochondria in red and white muscle with HIIT. Similarly, MCT2, a pyruvate transporter, and pyruvate dehydrogenase E1· protein contents per isolated mitochondrial protein remained unchanged after HIIT. CONCLUSIONS: These results suggest that high-intensity interval training improved fatty acid metabolism due to enhanced fatty acid transport, increased mitochondrial content, and to the increased intrinsic capacity for fatty acid oxidation in isolated SS and IMF mitochondria. This study is supported by NSERC, CIHR, the Heart and Stroke Foundation of Ontario, and the Canada Research Chair program.
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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) | 0.002 | 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".