Abstract
BackgroundAltitude training stimulates erythropoietin hormone (EPO) release and increases blood hemoglobin (Hb) mass, which may result in improved oxygen (O2) transport capacity. It was hypothesized in the present study that periodic inhalation of carbon monoxide (CO) might elicit similar physiological adaptations compared to altitude training.MethodsTwelve male college student athletes, who were well-trained soccer players, participated. They performed a 4-week treadmill-training program, five times a week. Participants were randomly assigned into an experimental group with inhaling CO (INCO) (1 mL/kg body weight for 2 min) in O2 (4 L) before all training sessions and a control group without inhaling CO (NOCO). CO and EPO concentrations in venous blood were first measured acutely at the 1st, 2nd, 4th, 6th, and 8th hour after INCO, and total hemoglobin mass (tHb), running economy and VO2max were measured before and after the 4 weeks training intervention.ResultsHbCO% increased from 0.7 to 4.4% (P < 0.05) after 1 h of CO inhalation and EPO increased from 1.9 to 2.7 mIU/mL after 4 h post CO inhalation (P < 0.05) acutely before the intervention. After the training, the tHb and VO2max in the INCO group increased significantly by 3.7 and 2.7%, respectively, while no significant differences were observed in the NOCO condition. O2 uptake at given submaximal speeds declined by approximately 4% in the INCO group.ConclusionAcutely, EPO increased sharply post CO inhalation, peaking at 4 h post inhalation. 4-weeks of training with CO inhalation before exercise sessions improved tHb and VO2max as well as running economy, suggesting that moderate CO inhalation could be a new method to improve the endurance performance in athletes.
Highlights
Altitude training has been widely applied in endurance sports for enhancing athletes’ maximal aerobic power (Levine and StrayGundersen, 1997)
The main physiological mechanism of the maximal aerobic power improvement may result from altitude training stimulating the secretion of erythropoietin hormone (EPO) from the kidneys, which increases the formation of red blood cells (RBC) from the bone marrow and raises circulating total hemoglobin mass (Chapman et al, 1998)
The results of the present study demonstrated that EPO concentration initially increased after one inhalation of Carbon monoxide (CO) (peaking at 4 h post inhalation (42.1%), gradually decreased over time), 4-week of sea level treadmill endurance training with an application of 1 mL/kg of CO inhalation 15 min prior to each 50-min training sessions increased subjects’ total hemoglobin (tHb) (3.7%), plasma (6.8%), and whole blood volume (6.2%), VO2max (2.7%), and running economy (4%)
Summary
Altitude training has been widely applied in endurance sports for enhancing athletes’ maximal aerobic power (Levine and StrayGundersen, 1997). Altitude training increases the ability of an individual to transport O2 to the working muscles, which enhance exercise power. If CO can enhance sporting performance, a sample of well-trained male individuals, who can have up to a 37% higher tHb in comparison to untrained athletes, (Kjellberg et al, 1949) is a suitable subject population as CO can remain in the blood for prolonged periods of time. Altitude training stimulates erythropoietin hormone (EPO) release and increases blood hemoglobin (Hb) mass, which may result in improved oxygen (O2) transport capacity. It was hypothesized in the present study that periodic inhalation of carbon monoxide (CO) might elicit similar physiological adaptations compared to altitude training
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