Evidence For Impaired Exercising Forearm And Leg Muscle Blood Flow At Higher Exercise Intensity In Copd
Bibliographic record
Abstract
Chronic Obstructive Pulmonary Disease (COPD) is characterized by extreme exercise intolerance. Patients often report leg discomfort as the reason for stopping, both during a progressive exercise test and during continuous exercise. Given the impact of compromised oxygen delivery on exercise performance it is possible that exercise intolerance is in part due to reduced exercising muscle oxygen delivery. PURPOSE: To test the hypothesis that exercising muscle oxygen delivery in both small (forearm handgrip) and large (leg kicking) muscle mass exercise is compromised in COPD. METHODS: 12 COPD (59.4 ±2.7 yrs, forced expiratory volume in 1 s (FEV1) 42.6 ±4.0% predicted) and 12 age and activity matched control subjects (60.5 ±2.8 yrs) participated in four exercise protocols on separate occasions: progressive increases in forearm handgrip and knee extension/flexion exercise to exhaustion, and step increases in forearm handgrip and knee extension/flexion to 50% peak work rate. Beat by beat Doppler and Echo ultrasound measures of forearm blood flow (FBF; brachial artery) and leg blood flow (LBF; femoral artery) and mean arterial blood pressure (MAP; arterial tonometry, Colin 5000), arterial oxygen saturation were made. Venous blood samples provided measures of Hb content (StatProfile M Blood Gas Analyzer, Nova Biomedical) RESULTS: data are mean ±SE. Peak forearm exercise intensity (weight lifted in lbs) for COPD was 83% of control (33.7 ±2.7 vs. 40.7 ±3.0). Forearm oxygen delivery (FOD; ml O2/min) was similar between COPD and Control until exercise intensity reached 25 lbs (COPD vs. Control FOD 76 ±5 vs. 96 ±9, P=0.058). However, there were no differences in any parameters quantifying blood flow kinetics with step increase to 50% peak (all P>0.60). Responses for leg exercise mirrored those for the forearm. CONCLUSIONS: Oxygen delivery to exercising muscle in COPD may be compromised at higher exercise intensities in both small and large muscle mass exercise. However, the speed with which oxygen delivery adjusts at exercise onset is not.
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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 | 0.001 | 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 | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".