The effects of hypobaric hypoxia on erythropoiesis, Maximal oxygen uptake and energy cost of exercise under normoxia in elite biathletes

The aim of the present study was to evaluate the effects of 3 weeks altitude training according to the HiHiLo (live high-base train high-interval train low) procedure as described by Chap-man et al. (1998),on erythropoiesis,maximal oxygen uptake and energy cost of exercise under normoxia in elite biathletes. Fifteen male elite biathletes randomly divided into an experi-mental (H) group (n = 7; age 27.1 ± 4.6 years; maximal oxygen uptake (VO2max) 66.9 ± 3.3 ml·kg-1·min-1; body height (BH) 1.81 ± 0.06 m; body mass (BM) 73.1 ± 5.4kg),and a control (C) group (n = 8; age 23.2 ± 0.9 years; VO2max 68.2 ± 4.1 ml·kg-1·min-1; BH 1.75 ± 0.03 m; BM 63.1 ± 1.5 kg) took part in the study. The H group stayed for 3 weeks at an altitude of 2015 m and performed endurance training on skis four times per week at 3000 m. Additionally,the training protocol included three high-intensity interval sessions at an altitude of 1000 m. The C group followed the same training protocol with skirollers in normoxia at an altitude of 600 m. The HiHiLo protocol applied in our study did not change VO2max or maximal workload (WRmax) significantly during the incremental treadmill test in group H. However,the energy cost for selected submaximal workloads in group H was significantly (p lt; 0.01) reduced compared to group C (-5.7%,-4.4%,-6% vs. -3.5%,-2.1%,-2.4%). Also a signifi-cant (p lt; 0.001) increase in serum EPO levels during the first two weeks of HiHiLo training at 2015 m was observed,associ-ated with a significant (p lt; 0.05) increase in hemoglobin mass,number of erythrocytes,hematocrit value and percent of reticu-locytes compared with initial values (by 6.4%,5%,4.6% and 16,6%,respectively). In group C,changes in these variables were not observed. These positive changes observed in our study led to a conclusion that the HiHiLo training method could improve endurance in normoxia,since most of the biathlon competitions are performed at submaximal intensities.