Cardiorespiratory and Muscle Oxygenation Responses to Isokinetic Exercise in Chronic Obstructive Pulmonary Disease
Bibliographic record
Abstract
PURPOSE: This study aimed to describe cardiorespiratory, quadriceps oxygenation, and muscle fatigue responses during a one-legged quadriceps isokinetic endurance exercise in chronic obstructive pulmonary disease (COPD) and control subjects. METHODS: Fourteen patients with COPD and 14 control subjects performed a cardiopulmonary cycling exercise test to exhaustion to assess peak oxygen consumption (V˙O2peak), minute ventilation (V˙Epeak), and heart rate (HRpeak). They also performed a quadriceps isokinetic endurance exercise consisting in 30 maximal knee extensions at 90°·s with continuous monitoring of expired gases, cardiac output, and oxygenation of the quadriceps by near-infrared spectroscopy. Total muscle work and fatigue index were also quantified. RESULTS: The total muscle work developed during the quadriceps isokinetic endurance exercise was 2.25 ± 0.57 kJ in COPD and 3.12 ± 0.60 kJ in controls, P < 0.001. In absolute terms, there were no between-group differences in V˙O2, V˙E, cardiac output, and HR at the end of quadriceps isokinetic endurance exercise. However, V˙E and HR reported that a fraction of their respective peak values during cardiopulmonary cycling exercise test were higher in COPD (V˙E/V˙Epeak, 69% ± 3%; HR/HRpeak, 82% ± 15%) compared with controls (V˙E/V˙Epeak, 45% ± 2%; HR/HRpeak, 71% ± 13%), all P < 0.05. During quadriceps isokinetic endurance exercise, quadriceps deoxyhemoglobin increased by 47% ± 31% in patients versus 33% ± 41% in controls (P < 0.05 from rest values) with a significant between-group differences (P = 0.025). The fatigue index during the quadriceps exercise was higher in COPD compared with controls. CONCLUSIONS: Although one-legged quadriceps isokinetic endurance exercise resulted in substantial central cardiorespiratory demands in COPD, this exercise was nevertheless associated with muscle overload as evidenced by muscle deoxygenation and higher muscle fatigue index in COPD compared with controls. These findings may have implications of the design of exercise training programs in COPD.
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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".