The DOI matches its Crossref record; 2 of the 2 references it cites were found in a registry or an index.
Chronic Exposure to Low-Dose Carbon Monoxide Alters Hemoglobin Mass and V˙O2max
Abstract
By blocking the oxygen binding sites on the hemoglobin molecule, chronic low-dose carbon monoxide (CO) administration may produce similar effects to those of exposure to altitude. Purpose: This study aimed to determine the effect of chronic low-dose CO application on hemoglobin mass (Hbmass) and V˙O 2max . Methods: For 3 wk, 11 healthy and moderately trained male subjects inhaled a CO bolus five times per day to increase their HbCO concentration by ~5%. Another 11 subjects received a placebo. Hbmass, serum erythropoietin concentration, ferritin, and basic hematological parameters were determined before and weekly during and until 3 wk after the CO inhalation period. V˙O 2max tests on a cycle ergometer were performed before and after the CO administration period. Results: In the CO group, Hbmass increased from 919 ± 69 to 962 ± 78 g in week 3 ( P < 0.001) and was maintained for the following 3 wk. Reticulocytes (%) and immature reticulocyte fraction significantly increased after 1 wk. Serum erythropoietin concentration tended to increase after 1 wk ( P = 0.07) and was suppressed in the postperiod ( P < 0.01). Ferritin decreased during the inhalation period (from 106 ± 37 to 72 ± 37 ng·mL −1 , P < 0.001). V˙O 2max tended to increase from 4230 ± 280 to 4350 ± 350 mL·min −1 ( P < 0.1) immediately after the inhalation period and showed a significant relationship to the change in Hbmass ( y = 4.1 x − 73.4, r = 0.70, P < 0.001). Conclusions: Chronic continuous exposure to low-dose CO enhances erythropoietic processes resulting in a 4.8% increase in Hbmass. The individual changes in Hbmass were correlated to the corresponding changes in V˙O 2max . Examination of ethical and safety concerns is warranted before the implementation of low-dose CO inhalation in the clinical/athletic setting as a tool for modifying Hbmass.
Overview
The claims and statistics of this paper haven’t been checked yet.
Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.
Integrity signals
Registry
Cites
Statistics
Verification
Claims the paper makes
The claims and statistics of this paper haven’t been checked yet.
Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
In the citing paper
“A previous study (Schmidt et al., 2020) demonstrated that administering six daily doses of CO, maintaining [COHb] at 4%–7% throughout the day over 3 weeks, effectively simulating a live‐high, train‐high approach, resulted in a 4.8% increase in Hbmass, which was correlated with a similar improvement in maximal oxygen consumption (V˙O2max) in healthy, moderately trained men.”
From Effect of live‐high, train‐low strategy induced by chronic low‐dose carbon monoxide exposure on haematological parameters and performance in trained individuals (2026) · cites this paper as Schmidt et al., 2020
In the citing paper
“Periodic inhalation of carbon monoxide (CO) at rest has been shown to mimic the effects of hypoxic training (Wang et al., 2019) and living at high altitude (Schmidt et al., 2020), with additive benefits when combined with natural high‐altitude exposure (Urianstad et al., 2024).”
From Effect of live‐high, train‐low strategy induced by chronic low‐dose carbon monoxide exposure on haematological parameters and performance in trained individuals (2026) · cites this paper as Schmidt et al., 2020
In the citing paper
“This upregulation of erythopoietin is likely to be the main stimulus driving the increase in Hbmass, as demonstrated following chronic CO supplementation (Schmidt et al., 2020).”
From Effect of live‐high, train‐low strategy induced by chronic low‐dose carbon monoxide exposure on haematological parameters and performance in trained individuals (2026) · cites this paper as Schmidt et al., 2020
In the citing paper
“Emerging evidence (Schmidt et al., 2020; Urianstad et al., 2024) suggests that carbon monoxide (CO) inhalation mimics hypoxic conditions (Richardson et al., 2002) by reducing functional haemoglobin availability (Douglas et al., 1912; Haldane, 1912), while stimulating erythropoiesis (Montero & Lundby, 2019) without causing hypoxic‐induced tachycardia and hypoxic ventilatory response (Hanada et al.,”
From Effect of live‐high, train‐low strategy induced by chronic low‐dose carbon monoxide exposure on haematological parameters and performance in trained individuals (2026) · cites this paper as Schmidt et al., 2020
In the citing paper
“This finding is opposite to a previous study, in which IRF increased after 1 week of daily CO administration, returning, and stayed at baseline levels during the remaining 2 of the total 3 weeks intervention (Schmidt et al., 2020).”
From Effect of live‐high, train‐low strategy induced by chronic low‐dose carbon monoxide exposure on haematological parameters and performance in trained individuals (2026) · cites this paper as Schmidt et al., 2020
12 more claims about this paper
Create a free account to see every claim other papers make about this one.
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
The self-check needs the paper’s full text.
Citations
Cites
Acute effects of cigarette smoking and inhalation of carbon monoxide during maximal exercise
Klausen, K., Andersen, C., & Nandrup, S. (1983) · European Journal of Applied Physiology and Occupational Physiology · doi:10.1007/bf00429074 · Cited by 67
Wang, J., Ji, Y., Zhou, L., Xiang, Y., Heinonen, I., & Zhang, P. (2019) · Frontiers in Physiology · doi:10.3389/fphys.2019.00701 · Cited by 22
Research works printed but not linked: 41
- 2015, Pharmacology of the ‘gasotransmitters’ NO, CO and H2S: translational opportunities, Br J Pharmacol, 172, 1395, 10.1111/bph.13005 · DOI
- 2015, CO and CO-releasing molecules (CO-RMs) in acute gastrointestinal inflammation, Br J Pharmacol, 172, 1557, 10.1111/bph.12632 · DOI
- 2015, The HO-1/CO system regulates mitochondrial-capillary density relationships in human skeletal muscle, Am J Physiol Lung Cell Mol Physiol, 309, L857, 10.1152/ajplung.00104.2015 · DOI · Paper page
- 2010, The therapeutic potential of carbon monoxide, Nat Rev Drug Discov, 9, 728, 10.1038/nrd3228 · DOI
- 2005, The optimised CO-rebreathing method: a new tool to determine total haemoglobin mass routinely, Eur J Appl Physiol, 95, 486, 10.1007/s00421-005-0050-3 · DOI · Paper page
- 2007, Loss of CO from the intravascular bed and its impact on the optimised CO-rebreathing method, Eur J Appl Physiol, 100, 383, 10.1007/s00421-007-0439-2 · DOI
- 2016, Acute, low-dose CO inhalation does not alter energy expenditure during submaximal exercise, Int J Sports Med, 37, 19
- 2016, Ten days of intermittent, low-dose carbon monoxide inhalation does not significantly alter hemoglobin mass, aerobic performance predictors, or peak-power exercise tolerance, Int J Sports Med, 37, 884, 10.1055/s-0042-108197 · DOI · Paper page
- 2010, Regulated oxygen sensing by protein hydroxylation in renal erythropoietin-producing cells, Am J Physiol Renal Physiol, 298, F1287, 10.1152/ajprenal.00736.2009 · DOI
- 2019, Smoking and increased white and red blood cells, Arterioscler Thromb Vasc Biol, 39, 965, 10.1161/ATVBAHA.118.312338 · DOI
- 2003, Second-generation blood tests to detect erythropoietin abuse by athletes, Haematologica, 88, 333
- 2004, Sample sizes for clinical trials with normal data, Stat Med, 23, 1921, 10.1002/sim.1783 · DOI · Paper page
- 2016, Diurnal changes of arterial oxygen saturation and erythropoietin concentration in male and female highlanders, Physiol Rep, 4
- 2010, Recurrent carbon monoxide poisoning from cigarette smoking, Am J Med Sci, 340, 427, 10.1097/MAJ.0b013e3181ef712d · DOI
- 1990, Blood gas transport properties in endurance-trained athletes living at different altitudes, Int J Sports Med, 11, 15, 10.1055/s-2007-1024755 · DOI
- 2019, Modelling the relationships between haemoglobin oxygen affinity and the oxygen cascade in humans, J Physiol, 597, 4193, 10.1113/JP277591 · DOI
- 2013, The effects of classic altitude training on hemoglobin mass in swimmers, Eur J Appl Physiol, 113, 1199, 10.1007/s00421-012-2536-0 · DOI
- 2011, The contribution of haemoglobin mass to increases in cycling performance induced by simulated LHTL, Eur J Appl Physiol, 111, 1089, 10.1007/s00421-010-1732-z · DOI
- 2016, Time for a new metric for hypoxic dose?, J Appl Physiol (1985), 121, 352, 10.1152/japplphysiol.00579.2015 · DOI · Paper page
- 1990, Triggering of erythropoietin production by hypoxia is inhibited by respiratory and metabolic acidosis, Am J Physiol, 258, R678
- 1978, Human llamas: adaptation to altitude in subjects with high hemoglobin oxygen affinity, J Clin Invest, 62, 593, 10.1172/JCI109165 · DOI · Paper page
- 1991, The effects of cigarette smoking upon hematological adaptations to moderately high altitude living, J Wild Med, 2, 274, 10.1580/0953-9859-2.4.274 · DOI
- 2012, No change in hemoglobin mass after 40 days of physical activity in previously untrained adults, Scand J Med Sci Sports, 22, 722, 10.1111/j.1600-0838.2011.01310.x · DOI
- 2008, Training in hypoxia and its effects on skeletal muscle tissue, Scand J Med Sci Sports, 38
- 2006, Increased serum erythropoietin but not red cell production after 4 wk of intermittent hypobaric hypoxia (4,000–5,500 m), J Appl Physiol (1985), 101, 1386, 10.1152/japplphysiol.00342.2006 · DOI
- 2008, Effects of various training modalities on blood volume, Scand J Med Sci Sports, 57
- 2017, Quantitative model of hematologic and plasma volume responses after ascent and acclimation to moderate to high altitudes, Am J Physiol Regul Integr Comp Physiol, 312, R265, 10.1152/ajpregu.00225.2016 · DOI
- 2019, Erythropoietic effects of low-dose cobalt application, Drug Test Anal, 11, 200, 10.1002/dta.2478 · DOI
- 2012, Short-term hematological effects upon completion of a four-week simulated altitude camp, Int J Sports Physiol Perform, 7, 79, 10.1123/ijspp.7.1.79 · DOI
- 2018, Effects of 3 weeks of oral low-dose cobalt on hemoglobin mass and aerobic performance, Front Physiol, 9, 1289, 10.3389/fphys.2018.01289 · DOI
- 2015, Monitoring recovery from iron deficiency using total hemoglobin mass, Med Sci Sports Exerc, 47, 419, 10.1249/MSS.0000000000000420 · DOI
- 2015, Adaptation of iron requirement to hypoxic conditions at high altitude, J Appl Physiol (1985), 119, 1432, 10.1152/japplphysiol.00248.2015 · DOI
- 2011, Predictive value of immature reticulocyte and platelet fractions in hematopoietic recovery of allograft patients, Transplant Proc, 43, 241, 10.1016/j.transproceed.2010.12.030 · DOI
- 1994, rh-erythropoietin stimulates immature reticulocyte release in man, Br J Haematol, 87, 605, 10.1111/j.1365-2141.1994.tb08320.x · DOI
- 2014, Monitoring of biological markers indicative of doping: the athlete biological passport, Br J Sports Med, 48, 827, 10.1136/bjsports-2014-093512 · DOI
- 2010, Impact of alterations in total hemoglobin mass on VO2max, Exerc Sport Sci Rev, 38, 68, 10.1097/JES.0b013e3181d4957a · DOI · Paper page
- 2013, Relationship between changes in haemoglobin mass and maximal oxygen uptake after hypoxic exposure, Br J Sports Med, 47, i26
- 2013, L’ultima frontiera del doping? Una boccata di gas tossico, Corriere della Sera
- 2000, Carbon monoxide poisoning—a public health perspective, Toxicology, 145, 1, 10.1016/S0300-483X(99)00217-6 · DOI · Paper page
- 1975, Predicting the carboxyhemoglobin levels resulting from carbon monoxide exposures, J Appl Physiol, 39, 633, 10.1152/jappl.1975.39.4.633 · DOI
- 1991, Schlamm in den Adern [Mud in the veins], Der Spiegel, 24, 191
Cited by
Gatterer, H., Dünnwald, T., Woyke, S., Faulhaber, M., Schumacher, Y. O., & Schobersberger, W. (2024) · Frontiers in Physiology · doi:10.3389/fphys.2024.1490205 · Cited by 13
Villanova, S., Porcelli, S., Ekström, L., & Cardinale, D. A. (2026) · Experimental Physiology · doi:10.1113/ep093005 · Cited by 5
Tobacco smoking: A stimulus for blood volume expansion
Sotiridis, A., Dardamanis-Aidonas, C., Makris, A., Loukas, I., Geladas, N., & Koskolou, M. (2026) · Respiratory Physiology & Neurobiology · doi:10.1016/j.resp.2025.104505 · Cited by 1
Metadata
- Authors
- SCHMIDT, W. F. J., HOFFMEISTER, T., HAUPT, S., SCHWENKE, D., WACHSMUTH, N. B., & BYRNES, W. C.
- Affiliations
- Department of Sports Medicine/Sports Physiology, University of Bayreuth, GERMANY
- Institute of Doping Analysis und Sports Biochemistry, University of Dresden, GERMANY
- Department of Integrative Physiology, University of Colorado, Boulder, CO
- Venue
- Medicine & Science in Sports & Exercise
- Published
- 2020-02-29
- Volume
- 52
- Issue
- 9
- Pages
- 1879-1887
- ISSN
- 1530-0315
- 0195-9131
- Cited by
- 39
- References
- 2
- Language
- en
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.
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.
