The Self-Contained Breathing Apparatus (SCBA) Influences Pulmonary Function and Respiratory Muscle Performance during Exercise
Bibliographic record
Abstract
PURPOSE: Previous work in our lab has shown that the increased external expiratory resistance of the SCBA regulator increases lung volumes and respiratory muscle work during heavy exercise, causing a ventilatory limitation and the potential for respiratory muscle fatigue. The purpose of the present study was to further examine the impact of the SCBA-imposed respiratory load on work of breathing, respiratory muscle function, and pulmonary function. METHODS: Twelve men (31 ± 8.4 yr) completed one graded step test in firefighting gear and breathing from the SCBA, then two randomized exercise sessions on separate days, each consisting of three 10 minute bouts of stepping exercise at 80% of maximal stepping cadence separated by 5 minutes recovery. Subjects wore protective gear including the SCBA for both sessions. The sessions consisted of breathing from (1) the SCBA regulator (BA) and (2) a low resistance breathing valve (RV). Spirometry was performed at baseline and in both the BA and RV conditions. Maximal inspiratory (MIP) and expiratory (MEP) mouth pressures were recorded before and within 5 minutes after exercise. During exercise, heart rate, ventilation, esophageal pressure, lung volume, and work of breathing were measured.TableRESULTS: The protective gear including the SCBA decreased FVC, FEV1 and peak expiratory flow (PEFR) compared to baseline (p < 0.001) in both conditions; however, the BA decreased FEV1 (p < 0.05) and PEFR (p < 0.01) to a greater degree than the RV. There were no differences in heart rate or ventilation during exercise. After 30 minutes of stepping exercise, the BA resulted in a decreased inspiratory capacity (3.16 vs. 3.39, p < 0.01) and an increased total (2129 vs.1427 cmH2O·L·min−1, p < 0.001), expiratory resistive (240 vs. 117 cmH2O·L·min−1, p < 0.001), and inspiratory elastic (1286 vs. 816 cmH2O·L·min−1, p < 0.001) work of breathing compared with the RV. Post exercise MEP and MIP were reduced with the BA (by 14.0 % and 12.3 %, respectively, p < 0.001), but not the RV (5.5 % and -0.01 %, respectively). CONCLUSIONS: Firefighting protective gear including the SCBA reduces resting pulmonary function, and increases exercising lung volumes, work of breathing, and respiratory muscle fatigue during stepping exercise. The results of this study suggest that a significant impairment of respiratory muscle function is likely present during heavy firefighting work and might lead to a reduction in respiratory muscle performance.
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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) | 0.002 | 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".