title: Ten Days of Intermittent, Low-dose Carbon Monoxide Inhalation does not Significantly Alter Hemoglobin Mass, Aerobic Performance Predictors, or Peak-power Exercise Tolerance.
abstract: Carbon monoxide (CO) rebreathing procedures are used to assess hemoglobin mass (Hbmass) but recent evidence suggests that CO is a signaling molecule that may alter physiological functions. We examined the effects of 10 days of intermittent, low-dose CO inhalation on Hbmass, aerobic performance predictors, and peak-power exercise tolerance. 18 recreationally-active men were randomized to either CO or placebo inhalation groups in a single-blind, pre-post parallel-groups trial. Primary outcomes were assessed before and after an intervention period during which subjects inhaled a bolus of 1.2 ml kg(-1) CO or placebo (room air) for 30 s, once per day on 10 days over a 12-day period. Cycling tests were performed >16 h following CO inhalation to exclude acute effects of CO exposure. CO inhalation elevated carboxyhemoglobin by 4.4±0.4% (mean±SD) following each exposure. Compared to placebo, chronic CO inhalation did not significantly alter Hbmass (p=0.99), peak oxygen uptake (p=0.59), peak power output (p=0.10), submaximal oxygen uptake (p=0.91), submaximal RER (p=0.22), lactate threshold (p=0.65), or peak-power exercise tolerance (p=0.60). In conclusion, our data support the ability to perform repeated measurements of Hbmass using CO rebreathing over a 12-day period without altering physiological responses.
authors.affiliation: Department of Integrative Physiology, University of Colorado Boulder, Boulder, United States.
authors.forename: B J
authors.initials: BJ
authors.lastname: Ryan
authors.affiliation: Department of Integrative Physiology, University of Colorado Boulder, Boulder, United States.
authors.forename: J A
authors.initials: JA
authors.lastname: Goodrich
authors.affiliation: Sports Medicine, Sports Physiology, University of Bayreuth, Bayreuth, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Schmidt
authors.affiliation: Department of Integrative Physiology, University of Colorado Boulder, Boulder, United States.
authors.forename: L A
authors.initials: LA
authors.lastname: Kane
authors.affiliation: Department of Integrative Physiology, University of Colorado Boulder, Boulder, United States.
authors.forename: W C
authors.initials: WC
authors.lastname: Byrnes
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D001642:Bicycling / Q000502:physiology; D002248:Carbon Monoxide / Q000008:administration & dosage*; D002263:Carboxyhemoglobin / Q000378:metabolism; D015444:Exercise / Q000502:physiology; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D016037:Single-Blind Method; D055815:Young Adult
chemical_list: D006454:Hemoglobins; D002248:Carbon Monoxide; D002263:Carboxyhemoglobin