Investigation of seasonal course of cardiopulmonary function and physiological exercise capacities among professional soccer players

Sporting performance, in team sports requiring intense exercise and endurance, is significantly influenced not only by the athlete's technical and tactical skills but also by their physiological capacity. The circadian regulation of physiological functions such as the cardiovascular system, muscle structure, and cellular energy may explain the daily variations in exercise capacity. However, the seasonal effects of these parameters and their impact on athletic capacity are not fully understood. This thesis aims to investigate how cardiopulmonary function and physiological exercise capacity change throughout the season in professional football players. In the study, all players of a professional male football team were evaluated during three phases of the season. To assess cardiopulmonary function and physiological exercise capacity, a symptom-limited, progressively intense protocol was used in a cardiopulmonary exercise test. Participants' sleep quality was measured using the Pittsburgh Sleep Quality Index, fatigue was assessed with the Multidimensional Fatigue Inventory, and depression was evaluated using the Beck Depression Inventory. The data was analyzed and a comparison was made. When all participants in the study were evaluated, the median age was 22 (IQR 20.0-27.0), the average height was 180.72±5.09 cm, the average weight was 75.05±6.39 kg, and the average body fat percentage was 12.38±2.68. The average maximum workload of all participants was found to be 231.83±27.85 watts. The VO₂max of all participants was 42.25±6.21 mL/kg/min, and the average heart rate during VO₂max was 156.09±24.81 beats per minute. When the separate evaluations for the three different periods of the season were compared, no statistically significant differences were found. Based on our study findings, an initial assessment should be made regarding the team's physiological parameters, focusing on cardiovascular capacity, respiratory system, and overall physiological endurance, depending on the football season. Although we cannot rule out that the results of our study may be related to athletes training during the off-season/pre-season, it suggests that the season-related performance changes observed in athletes may stem from the combination of multifaceted dynamics rather than just cardiopulmonary physiological parameters. Key Words: AerobBc capacBty, Football, MaxBmal exercBse, Performance, Sleep