The DOI matches its Crossref record; 44 of the 44 references it cites were found in a registry or an index; none of the 58 sources its claims cite is checked for support yet.
Carbon monoxide exposure during exercise performance: muscle and cerebral oxygenation
Open accessAbstract
Aim: To investigate the effect of carbon monoxide (CO) in the inspired air as anticipated during peak hours of traffic in polluted megalopolises on cerebral, respiratory and leg muscle oxygenation during a constant‐power test (CPT). In addition, since O 2 breathing is used to hasten elimination of CO from the blood, we examined the effect of breathing O 2 following exposure to CO on cerebral and muscle oxygenation during a subsequent exercise test under CO conditions. Methods: Nine men participated in three trials: (i) 3‐h air exposure followed by a control CPT, (ii) 1‐h air and 2‐h CO (18.9 ppm) exposure succeeded by a CPT under CO conditions (CPT COA), and (iii) 2‐h CO and 1‐h 100% normobaric O 2 exposure followed by a CPT under CO conditions (CPT COB). All exercise tests were performed at 85% of peak power output to exhaustion. Oxygenated (Δ[O 2 Hb]), deoxygenated (Δ[HHb]) and total (Δ[tHb]) haemoglobin in cerebral, intercostal and vastus lateralis muscles were monitored with near‐infrared spectroscopy throughout the CPTs. Results: Performance time did not vary between trials. However, the vastus lateralis and intercostal Δ[O 2 Hb] and Δ[tHb] were lower in CPT COA than in CPT. During the CPT COB, the intercostal Δ[O 2 Hb] and Δ[tHb] were higher than in the CPT COA. There were no differences in cerebral oxygenation between the trials. Conclusion: Inspiration of 18.9 ppm CO decreases oxygenation in the vastus lateralis and serratus anterior muscles, but does not affect performance. Breathing normobaric O 2 moderates the CO‐induced reductions in muscle oxygenation, mainly in the intercostals, but does not affect endurance.
Overview
CoChat Summary
TL;DR
In nine healthy men, breathing 18.9 ppm CO during constant-power cycling reduced vastus lateralis and serratus anterior oxygenation but did not change exercise performance time. Pre-exposure to normobaric O₂ moderated the CO-induced muscle deoxygenation, mainly in the intercostals, without improving endurance.
Key findings
- Performance time did not differ between control CPT (6:51 ± 1:28 min), CPT under CO (6:41 ± 1:39 min), and CPT under CO preceded by O₂ (6:52 ± 2:05 min; P > 0.05).
- Vastus lateralis Δ[O₂Hb] was lower in CPT CO_B (~25%) and CPT CO_A (~30%) than in CPT from 20% and 40% of performance time, respectively, until the end (P ≤ 0.05).
- Serratus anterior Δ[O₂Hb] fell more in CPT CO_A than in CPT and CPT CO_B at 60, 80, and 100% of performance time (P ≤ 0.05); Δ[tHb] was reduced in CPT CO_A vs CPT at 60 and 100%, and vs CPT CO_B at 100%.
- Cerebral oxygenation did not differ between trials, although cerebral Δ[HHb] was lower in both CO trials than in CPT (~42%) at peak exercise intensity (P ≤ 0.05). Blood lactate at termination was higher in CPT CO_A (13.5 ± 1.6 mM) than in CPT (12.8 ± 1.3 mM) and CPT CO_B (12.2 ± 1.3 mM; P < 0.001).
Methods
- Nine healthy, recreationally active non-smoking men (age 23.6 ± 3.0 years; VO₂max 51.3 ± 2.2 mL kg⁻¹ min⁻¹; PPO 357 ± 29 W) completed three counter-balanced trials separated by ≥48 h: 3-h air + control CPT; 1-h air + 2-h CO (18.9 ppm) + CPT under CO; and 2-h CO + 1-h 100% normobaric O₂ + CPT under CO.
- Exercise tests were constant-power cycle-ergometry at 85% PPO (mean 303 ± 24 W) to exhaustion. Near-infrared spectroscopy monitored Δ[O₂Hb], Δ[HHb], and Δ[tHb] in left prefrontal cortex, serratus anterior/intercostal region, and vastus lateralis.
- Analyses used one-way and two-way repeated-measures ANOVA with Tukey post hoc tests, plus Friedman and Wilcoxon tests for perceptual ratings; alpha was 0.05.
Limitations
- The paper states that NIRS cannot separate Hb and myoglobin contributions, subcutaneous adipose thickness may influence the signal, and NIRS reflects regional rather than global oxygenation.
- The paper notes that COHb was not recorded, so the presumed COHb threshold explanation is inferential.
- Evident from the text: the sample was small (nine men), participants were recreationally active but not formally trained, and the study examined a single pollutant rather than the pollutant mixture encountered in real urban environments.
Model-written summary. Check it against the paper before relying on it.
Integrity signals
Registry
Cites
Statistics
Verification
Claims the paper makes
0 Valid · 0 Not valid · 38 Not checked · 57 Own results and interpretations
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“However, PETCO 2 and HR were significantly lower, and SpO 2 was significantly higher during the 1-h O 2 breathing period compared to baseline and CO exposure in EXP CO + O 2 (P < 0.001).”
§ Carbon monoxide exposure during exercise performance: muscle and cerebral oxygenation > Pre-exercise exposures
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
None of the sources cited for this claim have been checked yet.
In the paper
“In the current CO trials, the respiratory muscle oxygenation showed a similar course to that of the leg muscle, as has also been noted in previous studies”
§ Carbon monoxide exposure during exercise performance: muscle and cerebral oxygenation > Muscle and cerebral oxygenation
plainstates an association- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The pre-exposure to normobaric hyperoxia did not change the pattern of the cerebral oxygenation during exercise.”
§ Carbon monoxide exposure during exercise performance: muscle and cerebral oxygenation > Cerebral oxygenation.
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“However, during the resting period, PETO 2 was significantly higher in the CPT CO B than in the CPT and CPT CO A , and PETCO 2 was significantly lower in the CPT CO B than in the CPT.”
§ Carbon monoxide exposure during exercise performance: muscle and cerebral oxygenation > Constant-power tests
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“However, [La] at the termination of exercise was significantly higher in the CPT CO A than in the CPT and CPT CO B (CPT: 12.8 Æ 1.3 mm, CPT CO A : 13.5 Æ 1.6 mm, CPT CO B : 12.2 Æ 1.3 mm; P < 0.001).”
§ Carbon monoxide exposure during exercise performance: muscle and cerebral oxygenation > Constant-power tests
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
52 more claims
Create a free account to see all 95 claims and to verify the 41 references still open.
- It may state two separate claims as one. 16
- Probably not a substantial claim. 21
- The quote only partly states this claim. 4
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
Each contradiction between two passages listed here was confirmed by an independent check.
Rated minor: it would not touch a result — a value no result rests on, a p-value that stays on the same side of the significance level, or a conflict that is clerical, resolved elsewhere in the paper, or outside its own findings.
In the paper
§ Carbon monoxide exposure during exercise performance: muscle and cerebral oxygenation > Abstract
“There were no differences in cerebral oxygenation between the trials.”
§ Carbon monoxide exposure during exercise performance: muscle and cerebral oxygenation > Cerebral oxygenation.
“D[HHb] was significantly lower in the CPT CO A and CPT CO B than in the CPT ($42%) at peak exercise intensity (P £ 0.05) (Fig. 4b).”
Citations
Cites
Maximal perfusion of skeletal muscle in man.
Andersen, P., & Saltin, B. (1985) · The Journal of Physiology · doi:10.1113/jphysiol.1985.sp015794 · Cited by 1,250
Duncan, A., Meek, J. H., Clemence, M., Elwell, C. E., Tyszczuk, L., Cope, M., & Delpy, D. T. (1995) · Physics in Medicine and Biology · doi:10.1088/0031-9155/40/2/007 · Cited by 650
Myoglobin O2 desaturation during exercise. Evidence of limited O2 transport.
Richardson, R. S., Noyszewski, E. A., Kendrick, K. F., Leigh, J. S., & Wagner, P. D. (1995) · Journal of Clinical Investigation · doi:10.1172/jci118237 · Cited by 647
Weaver, L. K. (2009) · New England Journal of Medicine · doi:10.1056/nejmcp0808891 · Cited by 626
Muscle O2 uptake kinetics in humans: implications for metabolic control
Grassi, B., Poole, D. C., Richardson, R. S., Knight, D. R., Erickson, B. K., & Wagner, P. D. (1996) · Journal of Applied Physiology · doi:10.1152/jappl.1996.80.3.988 · Cited by 561
Van Beekvelt, M. C. P., Colier, W. N. J. M., Wevers, R. A., & Van Engelen, B. G. M. (2001) · Journal of Applied Physiology · doi:10.1152/jappl.2001.90.2.511 · Cited by 430
Hamaoka, T., McCully, K. K., Quaresima, V., Yamamoto, K., & Chance, B. (2007) · Journal of Biomedical Optics · doi:10.1117/1.2805437 · Cited by 329
Effects of acute hypoxia on cerebral and muscle oxygenation during incremental exercise
Subudhi, A. W., Dimmen, A. C., & Roach, R. C. (2007) · Journal of Applied Physiology · doi:10.1152/japplphysiol.01460.2006 · Cited by 283
Amann, M., Romer, L. M., Subudhi, A. W., Pegelow, D. F., & Dempsey, J. A. (2007) · The Journal of Physiology · doi:10.1113/jphysiol.2007.129700 · Cited by 264
Wilson, J. R., Mancini, D. M., McCully, K., Ferraro, N., Lanoce, V, & Chance, B. (1989) · Circulation · doi:10.1161/01.cir.80.6.1668 · Cited by 256
Research works printed but not linked: 2
- AEA & Defra, 2010, Air Pollution in the UK 2009
- McCully K.K., 2000, Near‐infrared spectroscopy: what can it tell us about oxygen saturation in skeletal muscle?, Exerc Sport Sci Rev, 28, 123
Cited by
The neurovascular unit - concept review
Muoio, V., Persson, P. B., & Sendeski, M. M. (2014) · Acta Physiologica · doi:10.1111/apha.12250 · Cited by 564
The Health Effects of Exercising in Air Pollution
Giles, L. V., & Koehle, M. S. (2013) · Sports Medicine · doi:10.1007/s40279-013-0108-z · Cited by 297
Advances in the Role of Endothelial Cells in Cerebral Small Vessel Disease
Bai, T., Yu, S., & Feng, J. (2022) · Frontiers in Neurology · doi:10.3389/fneur.2022.861714 · Cited by 77
Zhou, C., Hopkins, W. G., Mao, W., Calvo, A. L., & Liu, H. (2019) · International Journal of Environmental Research and Public Health · doi:10.3390/ijerph16214238 · Cited by 66
Giorgini, P., Rubenfire, M., Bard, R. L., Jackson, E. A., Ferri, C., & Brook, R. D. (2015) · Journal of Cardiopulmonary Rehabilitation and Prevention · doi:10.1097/hcr.0000000000000139 · Cited by 63
Metadata
- Authors
- Keramidas, M. E., Kounalakis, S. N., Eiken, O., & Mekjavic, I. B.
- Affiliations
- Jožef Stefan Institute (SI)
- Hellenic Military Academy (GR)
- KTH Royal Institute of Technology (SE)
- Corresponding author
- Keramidas, M. E.
- Venue
- Acta Physiologica
- Publisher
- Wiley
- Published
- 2011-10-31
- Volume
- 204
- Issue
- 4
- Pages
- 544-554
- ISSN
- 1748-1708 (ISSN-L)
- 1748-1716
- OpenAlex
- W1858286946
- Semantic Scholar
- 1be4f47cb402517832317120e26572044ec6fc1e
- Cited by
- 19
- References
- 44
- Citations by year
- 2026: 1 · 2025: 2 · 2024: 1 · 2022: 1 · 2021: 2 · 2020: 1 · 2019: 4 · 2017: 3 · 2015: 1 · 2014: 2 · 2013: 1
- FWCI
- 0.65
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Acta Physiologica (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Health Sciences › Medicine › Physiology (medical) › Cardiovascular and exercise physiology
- Health Sciences › Medicine › Physiology (medical) › Exercise and Physiological Responses
- Physical Sciences › Environmental Science › Health, Toxicology and Mutagenesis › Air Quality and Health Impacts
- Keywords
- carbon monoxide exposure, exercise performance, muscle oxygenation, cerebral oxygenation, hemoglobin oxygenation, vastus lateralis, intercostal muscles, endurance, air pollution, traffic-related air pollution
- MeSH terms
- Air Pollutants, Air Pollution, Brain, Carbon Monoxide, Humans, Male, Oxygen, Respiratory Physiological Phenomena, Exercise, Muscle, Skeletal, Young Adult
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
A language model drew the claims from the paper on 2026-11-13, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).
A second model labelled each claim on 2026-11-13 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
Are you an author, or do you see a problem with this page? Request a review
Data sources
Bibliographic data: Semantic Scholar, OpenAlex, Crossref.
Contains information from the Semantic Scholar Academic Graph Datasets, made available under the ODC Attribution License (ODC-BY 1.0).
Semantic Scholar’s data is described in: Kinney, R., et al. (2023). The Semantic Scholar Open Data Platform. arXiv:2301.10140.
