Proximal Versus Distal Tissue Oxygenation In Vastus Lateralis During Incremental Cycling
Bibliographic record
Abstract
It has been shown in humans that tissue oxygenation heterogeneity may exist within a specific muscle or between different muscle groups during exercise. However, the specific tissue oxygenation pattern within a muscle with increased metabolic demand is not well understood. More specifically, it is unclear whether the oxygenation of vastus lateralis during cycling exercise is similar between proximal and distal regions of the muscle. PURPOSE To examine differences in regional tissue oxygenation of the vastus lateralis during incremental cycling. METHODS Two spatially resolved Near infrared spectroscopy probes (NIRO 300; Hamamatsu Photonics, Japan) were placed at 15 cm and 25 cm above the right knee on the vastus lateralis. Participants (N = 25; Age: 24 ± 4 yrs; Ht: 183 ± 7 cm; Wt: 79 ± 10 kg; VO2max: 55 ± 9 mL/kg/min) rested quietly and then performed a graded exercise test to maximum (30 watt/min increase). Tissue oxygenation index (TOI) was measured continuously, and then averaged every 1 minute off line. RESULTS A repeated measures ANOVA (probe placement × exercise intensity) showed a main effect for probe placement (p = 0.03) and a main effect for intensity (p = 0.00) with no interaction effect. Pairwise comparison of proximal versus distal probe revealed that the distal probe TOI was less than the proximal probe TOI at rest and throughout exercise (mean difference = 2.6%). At workloads greater than 30 watts, TOI decreased significantly at each workload (mean difference = 2.0%). CONCLUSIONS These results indicate that tissue oxygenation heterogeneity may exist in exercising skeletal muscle in humans. The increased proximal tissue oxygenation compared to the distal region of vastus lateralis may indicate a pattern of enhanced availability of oxygen to the proximal region that persists over a wide range of metabolic demand. Lastly, the stepped decrease in TOI with each workload reflects the controlled nature of tissue oxygenation in exercising skeletal muscle. Supported by: University of Alberta “Support for the Advancement of Scholarship”; Michael Smith Foundation for Health Research; BC Neurotrauma Fund; Canada Foundation for Innovation.
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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".