Impairment in maximal lactate steady state after carbon monoxide inhalation is related to training status
Bibliographic record
Abstract
New Findings What is the central question of this study? What is the effect of an elevated carboxyhaemoglobin (COHb) concentration following carbon monoxide inhalation on the maximal lactate steady state (MLSS) in humans and is this effect dependent on aerobic fitness? What is the main finding and its importance? An elevated COHb concentration intensified physiological responses to exercise at the MLSS – including heart rate, ventilation and peripheral fatigue – in general and reduced the MLSS (i.e., destabilized the blood lactate concentration) in trained but not untrained males and females. Abstract This study investigated whether a lower effective [Hb], induced by carbon monoxide (CO) inhalation, reduces the peak oxygen uptake () and the maximal lactate steady state (MLSS) and whether training status explains individual variation in these impairments. Healthy young participants completed two ramp incremental tests (n = 20, 10 female) and two trials at MLSS (n = 16, eight female) following CO rebreathe tests and sham procedures (SHAM) in random orders. All fitness variables were normalized to fat‐free mass (FFM) to account for sex‐related differences in body composition, and males and females were matched for aerobic fitness. The (mean (SD): −4.2 (3.7)%), peak power output (PPO) (−3.3 (2.2)%) and respiratory compensation point (RCP) (−6.3 (4.5)%) were reduced in CO compared with SHAM (P < 0.001 for all), but the gas exchange threshold (−3.3 (7.1)%) was not (P = 0.077). Decreases in (r = −0.45; P = 0.047) and PPO (r = −0.49; P = 0.029) in CO were correlated with baseline aerobic fitness. Compared to SHAM, physiological and perceptual indicators of exercise‐related stress were exacerbated by CO while cycling at MLSS. Notably, the mean blood lactate concentration ([La]) increased (i.e., Δ[La] >1.0 mM) between 10 min (5.5 (1.4) mM) and 30 min (6.8 (1.3) mM; P = 0.026) in CO, with 9/16 participants classified as unstable. These unstable participants had a higher (66.2 (8.5) vs. 56.4 (8.8) ml kg FFM−1 min−1, P = 0.042) and at MLSS (55.8 (7.0) vs. 44.3 (7.0) ml kg FFM−1 min−1, P = 0.006) compared to the stable group. In conclusion, a reduced O2‐carrying capacity decreased maximal and submaximal exercise performance, with higher aerobic fitness associated with greater impairments in both.
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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 | 0.000 | 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".