A practical model of low-volume high-intensity interval training induces mitochondrial biogenesis in human skeletal muscle: potential mechanisms
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Bibliographic record
Abstract
High-intensity interval training (HIT) induces skeletal muscle metabolic and performance adaptations that resemble traditional endurance training despite a low total exercise volume. Most HIT studies have employed 'all out', variable-load exercise interventions (e.g. repeated Wingate tests) that may not be safe, practical and/or well tolerated by certain individuals. Our purpose was to determine the performance, metabolic and molecular adaptations to a more practical model of low-volume HIT. Seven men (21 + or - 0.4 years, V(O2peak) = 46 + or - 2 ml kg(-1) min(-1)) performed six training sessions over 2 weeks. Each session consisted of 8-12 x 60 s intervals at approximately 100% of peak power output elicited during a ramp V(O2) peak test (355 + or - 10 W) separated by 75 s of recovery. Training increased exercise capacity, as assessed by significant improvements on both 50 kJ and 750 kJ cycling time trials (P < 0.05 for both). Skeletal muscle (vastus lateralis) biopsy samples obtained before and after training revealed increased maximal activity of citrate synthase (CS) and cytochrome c oxidase (COX) as well as total protein content of CS, COX subunits II and IV, and the mitochondrial transcription factor A (Tfam) (P < 0.05 for all). Nuclear abundance of peroxisome proliferator-activated receptor gamma co-activator 1alpha (PGC-1alpha) was approximately 25% higher after training (P < 0.05), but total PGC-1alpha protein content remained unchanged. Total SIRT1 content, a proposed activator of PGC-1alpha and mitochondrial biogenesis, was increased by approximately 56% following training (P < 0.05). Training also increased resting muscle glycogen and total GLUT4 protein content (both P < 0.05). This study demonstrates that a practical model of low volume HIT is a potent stimulus for increasing skeletal muscle mitochondrial capacity and improving exercise performance. The results also suggest that increases in SIRT1, nuclear PGC-1alpha, and Tfam may be involved in coordinating mitochondrial adaptations in response to HIT in human skeletal muscle.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 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 | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 it