Relationship Between Deoxy-hemoglobin And Vo2 During Ramp Incremental And Steady-state Constant-load Exercise
Bibliographic record
Abstract
The matching of local blood flow (Qm)-to-muscle O2 utilization (VO2m) can be discerned from the ratio of muscle deoxygenation ([HHb], reflecting fractional O2 extraction) to pulmonary VO2 (VO2p). Given a linear 'steady-state' Qm-to-VO2m relationship, the fractional O2 extraction is expected to increase hyperbolically with increasing VO2m. PURPOSE: To examine the [HHb]-to-VO2p relationship during steady-state, constant-load (CL) exercise and non-steady-state ramp incremental (RI) exercise in healthy young adults. METHODS: Subjects (n=9 males, 25 (5) yrs; mean (SD)) completed 2 RI exercise tests (20 W/min) to volitional fatigue along with 6 repetitions of CL step transitions from 6 min at 20W baseline to work rates corresponding to i) a relative intensity of ∼ 80% of the estimated lactate threshold (80% LT), and ii) an absolute intensity of 50 W; with each step transition lasting 6 min. VO2p was measured breath-by-breath using a volume turbine and a mass spectrometer; muscle deoxygenation ([HHb]) of the vastus lateralis muscle was measured using near-infrared spectroscopy. VO2p and [HHb] profiles were modeled as a mono-exponential using non-linear regression. The [HHb]-to-VO2p ratio was calculated in CL as the difference from 20W baseline to steady-state at 50W or 80% LT, and during RI as the slope of the [HHb]-to-VO2p relationship (VO2p range, 1.0 - 3.0 L/min) as determined by linear regression. RESULTS: The [HHb]-to-VO2p ratio was not different (p>0.05) at steady-states of 50W (12.0 (6.8) a.u.) and 80% LT (10.3 (4.8) a.u.) CL, or during the non-steady-state of RI (8.7 (2.9) a.u.). CONCLUSION: The similar [HHb]-to-VO2p relationship, reflecting fractional O2 extraction for a given VO2, measured during steady-state (CL) and non-steady-state (RI) exercise suggests that the Qm-to-VO2m relationship was unchanged regardless of the condition (i.e. CL or RI). Supported by: NSERC
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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 | 0.002 |
| 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".