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

Abstract

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 (FiO2 = 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 (FiO2 = 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.

Keywords: altitude training; anabolic–catabolic response; cortisol; hypoxia; testosterone.

Figure 1

Blood serum testosterone levels (T) in experimental (LH–TL and IHT) and control (N) groups during the first experiment; ** p < 0.01—statistically significant differences compared to baseline.

Figure 2

Blood serum cortisol levels (C) in experimental (LH–TL and IHT) and control (N1) groups during the first experiment.

Figure 3

Blood serum testosterone/cortisol ratio (T/C) in experimental (LH–TL and IHT) and control (N) groups during the experiment; ** p < 0.01—statistically significant differences compared to baseline.

Figure 4

Area under the curve (AUC) calculated from testosterone levels over 4 weeks in experimental (LH–TL and IHT) and control (N) groups; * p < 0.05—statistically significant differences.

Figure 5

Correlation between area under the curve (AUC) for testosterone levels over 4 weeks (AUC testosterone) and delta values of hemoglobin concentration (∆HGB) during the experiment in the LH–TL group.