Chronic Exposure to Normobaric Hypoxia Increases Testosterone Levels and Testosterone/Cortisol Ratio in Cyclists

The aim of this study was to analyze the effects of the “live high, train low” method (LH–TL) and intermittent hypoxic training (IHT) on testosterone (T) and cortisol (C) levels in cyclists. Thirty cyclists participated in the experiment. The LH–TL group (n = 10) was exposed to normobaric hypoxia (FiO(2) = 16.3%) for 11–12 h a day and trained in normoxia for 3 weeks. In the IHT group (n = 10), participants followed the IHT routine three times a week for 3 weeks in normobaric hypoxia (FiO(2) = 16.3%). The control group (N; n = 10) followed the same training protocol in normoxia. The LH–TL training was found to significantly increase (p < 0.05) T levels and the testosterone/cortisol (T/C) ratio during the experiment. The area under the curve (AUC) calculated for T levels over 4 weeks was significantly (p < 0.05) higher in the LH–TL group, by 25.6%, compared to the N group. The results also indicated a significant correlation (r = 0.53; p < 0.05) between AUC for T levels over 4 weeks and ∆ values of hemoglobin (HGB) in the LH–TL group. Overall, the findings show that LH–TL training at a moderate simulated altitude contributes to an increase in T levels and T/C ratio in athletes, which is a beneficial change stimulating anabolic processes and erythropoiesis.