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.

Key words

carboxyhemoglobin - exercise testing - gasotransmitter

• References

• 1 Abellán R, Remacha AF, Ventura R, Sardà MP, Segura J, Rodríquez FA. Hematological response to four weeks of intermittent hypobaric hypoxia in highly trained athletes. Haematolgica 2005; 90: 126-127
• 2 Batterham AM, Hopkins WG. Making meaningful inferences about magnitudes. Int J Sports Physiol Perform 2006; 1: 50-57
• 3 Bruce EN, Bruce MC. A multicompartment model of carboxyhemoglobin and carboxymyoglobin responses to inhalation of carbon monoxide. J Appl Physiol 2003; 95: 1235-1247
• 4 Coyle EF, Martin WH, Ehsani AA, Hagberg JM, Bloomfield SA, Sinacore DR, Holloszy JO. Blood lactate threshold in some well-trained ischemic heart disease patients. J Appl Physiol 1983; 54: 18-23
• 5 De Pauw K, Roelands B, Cheung SS, de Gues B, Rietjens G, Meeusen R. Guidelines to classify subject groups in sport-science research. Int J Sports Physiol Perform 2013; 8: 111-122
• 6 Eastwood A, Hopkins WG, Bourdon PC, Withers RT, Gore CJ. Stability of hemoglobin mass over 100 days in active men. J Appl Physiol 2008; 104: 982-985
• 7 Eckardt K-U, Kurtz A, Bauer C. Triggering of erythropoietin production by hypoxia is inhibited by respiratory and metabolic acidosis. Am J Physiol 1990; 27: R678-R683
• 8 Garvican LA, Burge CM, Cox AJ, Clark SA, Martin DT, Gore CJ. Carbon monoxide uptake kinetics of arterial, venous, and capillary blood during CO rebreathing. Exp Physiol 2010; 95: 1156-1166
• 9 Garvican LA, Eastwood A, Martin DT, Ross MLR, Gripper A, Gore CJ. Stability of hemoglobin mass during a 6-day UCI ProTour cycling race. Clin J Sports Med 2010; 20: 200-204
• 10 Gore CJ, Rodriguez FA, Truijens MJ, Townsend NE, Stray-Gundersen J, Levine BD. Increased serum erythropoietin but not red cell production after 4 wk of intermittent hypobaric hypoxia (4,000–5,500 m). J Appl Physiol 2006; 101: 1386-1393
• 11 Harriss DJ, Atkinson G. Ethical standards in sport and exercise science research: a 2016 update. Int J Sports Med 2015; 36: 1121-1124
• 12 Holloszy JO, Coyle EF. Adaptations of skeletal muscle to endurance exercise and their metabolic consequences. J Appl Physiol 1984; 56: 831-838
• 13 Hopkins WG. Spreadsheets for analysis of controlled trials, with adjustment for a subject characteristic. Sportscience 2006; 10: 46-50
• 14 Hopkins WG, Marshall SW, Batterham AM, Hanin J. Progressive statistics for studies in sports medicine and exercise science. Med Sci Sports Exerc 2009; 1: 3-12
• 15 Jelkmann W, Seidl J. Dependence of erythropoietin production on blood oxygen affinity and hemoglobin concentration in rats. Biomed Biochim Acta 1987; 46: S304-S308
• 16 Kane LA, Ryan BJ, Schmidt WF, Byrnes WC. Acute, low-dose CO inhalation does not alter energy expenditure during submaximal exercise. Int J Sports Med 2015; 37: 19-24
• 17 Motterlini R, Otterbein LE. The therapeutic potential of carbon monoxide. Nature Drug Disc 2010; 9: 728-743
• 18 Pecorella SRH, Potter JVF, Cherry AD, Peacher DF, Welty-Wolf KE, Moon RE, Piantadosi CA, Suliman HB. The HO-1/CO system regulates mitochondrial-capillary density relationships in human skeletal muscle. Am J Physiol 2015; 309: L857-L871
• 19 Prommer N, Schmidt W. Loss of CO from the intravascular bed and its impact on the optimised CO-rebreathing method. Eur J Appl Physiol 2007; 100: 383-391
• 20 Rhodes MA, Carraway MS, Piantadosi CA, Reynolds CM, Cherry AD, Wester TE, Natoli MJ, Massey EW, Moon RE, Suliman HB. Carbon monoxide, skeletal muscle oxidative stress, and mitochondrial biogenesis in humans. Am J Physiol 2008; 297: H392-H399
• 21 Schmidt W, Prommer N. The optimised CO-rebreathing method: a new tool to determine total haemoglobin mass routinely. Eur J Appl Physiol 2005; 95: 486-95
• 22 Sinclair LM, Hinton PS. Prevalence of iron deficiency with and without anemia in recreationally active men and women. J Am Diet Assoc 2005; 105: 975-978
• 23 Weaver LK. Carbon monoxide poisoning. N Engl J Med 2009; 360: 1217-1225
• 24 Wilber RL, Stray-Gundersen J, Levine BD. Effect of hypoxic “dose” on physiological responses and sea-level performance. Med Sci Sports Exerc 2007; 39: 1590-1599