The purpose of this study was to examine the effect of short-term intermittent normobaric hypoxia on the submaximal cycling efficiency and hemoglobin O₂ affinity in endurance cyclist. Twelve-male elite endurance cyclists were divided into a normoxic (N, n=6) or a hypoxic group (H, n=6). H group cyclists stayed in a normobaric hypoxic room (15.4% O₂; 2500m) for 10-12h a day at night over 5 days, with training sessions at sea-level. Before and after the experimental period, subjects were undergone the submaximal treadmill cycling and hematological tests. Submaximal cycling efficiency was measured at the intensities of 50% and 80% of VO₂max predetermined during baseline test. Also, resting RBC, Hb, Hct, Ret, 2･3-DPG and oxyhemoglobin dissociation curve (ODC) were measured before (pre) and 5th day (after) of the experiment period. ODC was shift to the right by hypoxia. P₅₀ value of H group was significantly increased (p<0.05) on the 5th day (29.83mmHg) compared with the pre-value (28.19mmHg). RBC, Hb and Hct were not changed by hypoxia. After experimental period, VO₂ at 50% and 80% of VO₂max of H group were significantly decreased (p<0.05) by 15% and 18% compared with pre-values, respectively. HR and Blood lactate concentration at both intensities were also significantly decreased from the pre-values (p<0.05) in H group. There were no different in VE, VO₂, HR and blood lactate concentration of N group at both intensities. From these results, it was concluded that short-term intermittent normobaric hypoxia shifts ODC to the right and could contribute to the improvement of submaximal cycling efficiency in endurance cyclist.

DESCENTE SPORTS SCIENCE Vol.27/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE