Kinetics of Pulmonary O2 Uptake and Muscle Deoxygenation During Active and Passive Recovery
Bibliographic record
Abstract
The rate of recovery (i.e., decrease) of local O2 delivery and O2 utilization following exercise may be altered by passive or active recovery and may affect the recovery of pulmonary O uptake (VO) kinetics. PURPOSE: To determine the rate of recovery of local muscle deoxygenation during active and passive recovery from moderate-intensity exercise and the relationship with the time course of VO2p recovery. METHODS: 5 male subjects performed repeated step-transitions (6 min) from mo derate-intensity (90% θL) alternate-leg knee-extension to active (A-KE; ∼5 W) or passive (P-KE) recovery. VO2p was measured breath-by-breath by mass spectrometer and volume turbine. Deoxy- (HHb), oxy- (HbO2), and total (Hbtot) Hb/Mb of the vastus lateralis muscle were measured continuously by near-infrared spectroscopy (NIRS; Hamamatsu NIRO-300). The VO2p and HHb data were filtered, time-aligned and ensemble-averaged to provide a single response for each subject. VO2p data were then averaged to 10 s bins and fit with a mono exponential function during the phase 2 recovery. HHb data were averaged to 5 s bins and fit with a monoexponential function from the start of recovery. RESULTS: The decrease in VO2p during recovery was smaller (p<0.05) in A-KE (0.59 ±0.18 L-min·1) than P-KE (0.80 ±0.16 L·min−1), with end-recovery VO2p higher (p<0.05) in A-KE (0.57 ± 0.03 L·min−1) than P-KE (0.44 ± 0.04 L·min−1). The τVO2p was not different in A-KE (30 ± 2 s) and P-KE (30 ± 3 s). The amplitude of the decrease in HHb during recovery, and end-recovery HHb were not different between A-KE and P-KE. Recovery τHHb in A-KE was 49 ± 9 s vs. 74 ± 29 s in P-KE. Although for the present sample this difference was not significant, 4 of the 5 subjects had a shorter τHHb in A-KE than P-KE. CONCLUSIONS: The trend for a prolonged elevation of muscle deoxygenation with passive recovery consequent to a greater fall in VO2 with similar off-transient kinetics to that of active recovery suggests a need to maintain excess O2 extraction, likely as a consequence of a larger decrease in local muscle O2 delivery. (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 | 0.001 |
| 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".