2.1. Study Participants
This study involved 16 young men (aged 18 to 25 years) participating in competitive, Olympic-style boxing. The inclusion criteria required a minimum of a six-month washout period from previous altitude/hypoxic training and baseline blood testosterone levels within the age-specific reference range.The participants were randomly assigned to the experimental group (DAA) and the control group (C) and underwent 14 days of supplementation. The DAA group (n = 8; age = 20.6 ± 2.1 years; height = 177.5 ± 1.7 cm; body mass = 75.1 ± 8.1 kg; % body fat = 10.5 ± 2.3; VOAll participants had current valid medical examinations confirming they were in good health and could practice sports. Before commencing this study, all participants were informed about the purpose and course of this study and provided their written consent to participate. The athletes were also informed that they could withdraw from this study at any time without needing to provide a reason. Additionally, participants declared that for at least one month before testing, they had not taken any medications or dietary supplements. This study was approved by the ethics committee of the Institute of Sport—National Research Institute in Warsaw (No. KEBN-22-73-KP, 2 November 2022).