Is Muscle Deoxygenation Heterogeneous During Moderate- and Heavy-Intensity Cycling Exercise in Young and Older Adults?
Bibliographic record
Abstract
0168 Near-infrared spectroscopy (NIRS) measures of muscle deoxygenation (HHb) reflect the regional balance between local muscle O2 delivery and O2 utilization. PURPOSE: To examine regional differences in local muscle deoxygenation during the on-transient of moderate- and heavy- intensity cycling exercise in young (Y) and older (O) adults. METHODS: Y (n = 5; 25 ± 3 y) and O (n = 5; 67 ± 4 y) adults performed step-transitions (6 min) from 20 W to moderate-intensity (MOD; 80% θL) and heavy-intensity (HVY; Δ 50%) cycling exercise. Deoxy-(HHb), oxy- (HbO2), and total Hb/Mb (HbTOT) of the vastus lateralis (VL) and vastus medialis (VM) muscles were measured continuously by NIRS (Hamamatsu NIRO-300). HHb data were fit with a mono-exponential model. RESULTS: In Y, the amplitude of the increase in HHb (HHb-Amp) was greater (p<0.05) in the VM muscle than in VL muscle during MOD (VM: 14 ± 3 μM; VL: 6 ± 2 μM) and HVY (VM: 26 ± 7 μM; VL: 16 ± 8 μM), whereas HHb-Amp was similar between the muscles of O adults during MOD (VM: 4 ± 2 μM; VL: 5 ± 1 μM) and HVY (VM: 7 ± 4 μM; VL: 12 ± 4 μM). The pulmonary τVO2 was slowed in O compared to Y in both MOD and HVY. The rate of adaptation of HHb (τHHb) was similar in Y and O in the VL and VM during MOD. However, during HVY, τHHb was faster in O compared to Y (p<0.05) in both VM (O: 7 ± 4 s; Y: 14 ± 2 s) and VL (O: 8 ± 2 s; Y: 11 ± 3 s). CONCLUSIONS: These results demonstrate heterogeneous muscle deoxygenation during MOD and HVY exercise in Y, but not in O adults. Differences in recruitment of muscle groups between O and Y adults cannot be ruled out, however the more rapid muscle deoxygenation during HVY in O suggests that the distribution and delivery of local muscle blood flow relative to O2 utilization may be diminished in O compared to Y adults. Supported by NSERC, Canada.
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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 | 0.001 | 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".