The Impact of Normobaric Hypoxia-inducing High-Intensity Interval Training Program on the Expression Levels of Selected miRNAs and Running Economy in Endurance-trained Athletes

INTERVENTION: The objective of this study is to assess the impact of a 6‐week High‐Intensity Interval Training (HIIT) program under normobaric hypoxic conditions on the expression levels of selected miRNAs and running economy in endurance athletes. The research will be conducted as an experimental study on male track and field athletes specializing in middle and long‐distance events (n=32) in four stages. In the first stage, which will last for two weeks, volunteers will be recruited for the experiment, and all participants will undergo somatic measurements using bioelectrical impedance analysis (BIA) to determine body composition. The second stage, which will commence immediately after somatic measurements, will be divided into four parts, during which aerobic performance measurements will be conducted in hypoxia (3000 m above sea level), normoxia, running economy tests, and eccentric contraction‐dominant effort measurements. Blood samples will be collected before and after each exercise test for biochemical analyses, and all tests will be conducted with appropriate methodological 3‐day intervals. In the third stage of the study, athletes will be randomly assigned to four groups, each consisting of 8 individuals: control, experimental with temporary exposure to hypoxia without training, experimental LLTL, and experimental LLTH. Athletes allocated to the experimental LLTL group will incorporate a 6‐week (3 times a week) normoxic HIIT training program into their training plan, while the experimental LLTH group will undergo a 6‐week (3 times a week) hypoxic HIIT training program. The training program will be conducted in a hypoxic chamber (two training groups of 4 individuals each) located at the Physiological Basis of Adaptation Laboratory, Bronislaw Czech Academy of Phy CONDITION: Aerobic performance;Impact of Normobaric Hypoxia on the Human Body;Running economy; ; Aerobic performance ; Impact of Normobaric Hypoxia on the Human Body ; Running economy Blood ‐ Normal development and function of platelets and erythrocytes Respiratory ‐ Normal development and function of the respiratory system PRIMARY OUTCOME: Changes in morphological parameters, running economy, threshold and maximum values before and after applying the training program. Running economy, threshold and maximum values assessed by VO2peak tests.; [ 6 weeks after completion of the training program.] Expression Levels of Selected miRNAs assessed by blood test.[ 6 weeks after completion of the training program.] SECONDARY OUTCOME: Nil[ Nil] INCLUSION CRITERIA: ‐ Athletes specializing in middle and long‐distance events ‐ Aged 18 years or older ‐ No contraindications to physical exercise ‐ Absence of diagnosed metabolic disorders ‐ Not currently undergoing pharmacotherapy