ABSTRACT: Background:The regular assessment of hormonal and mood state parameters in professional soccer are proposed as good indicators during periods of intense training and/or competition to avoid overtraining. Objective:The aim of this study was to analyze hormonal, psychological, workload and physical fitness parameters in elite soccer players in relation to changes in training and match exposure during a congested period of match play. Methods:Sixteen elite soccer players from a team playing in the first Tunisian soccer league were evaluated three times (T1, T2, and T3) over 12 weeks. The non-congested period of match play was from T1 to T2, when the players played 6 games over 6 weeks. The congested period was from T2 to T3, when the players played 10 games over 6 weeks. From T1 to T3, players performed the Yo-Yo intermittent recovery test level 1 (YYIR1), the repeated shuttle sprint ability test (RSSA), the countermovement jump test (CMJ), and the squat jump test (SJ). Plasma Cortisol (C), Testosterone (T), and the T/C ratio were analyzed at T1, T2, and T3. Players had their mood dimensions (tension, depression, anger, vigor, fatigue, confusion, and a Total Mood Disturbance) assessed through the Profile of Mood State questionnaire (POMS). Training session rating of perceived exertion (sRPE) was also recorded on a daily basis in order to quantify internal training load and elements of monotony and strain. Results:Significant performance declines (T1 < T2 < T3) were found for SJ performance (p = 0.04, effect size [ES] ES1 - 2 = 0.15-0.06, ES2 - 3 = 0.24) from T1 to T3. YYIR1 performance improved significantly from T1 to T2 and declined significantly from T2 to T3 (p = 0.001, ES1 - 2 = 0.24, ES2 - 3 = -2.54). Mean RSSA performance was significantly higher (p = 0.019, ES1 - 2 = -0.47, ES2 - 3 = 1.15) in T3 compared with T2 and T1. Best RSSA performance was significantly higher in T3 when compared with T2 and T1 (p = 0.006, ES2 - 3 = 0.47, ES1 - 2 = -0.56), but significantly lower in T2 when compared with to T1. T and T/C were significantly lower in T3 when compared with T2 and T1 (T: p = 0.03, ES3 - 2 = -0.51, ES3 - 1 = -0.51, T/C: p = 0.017, ES3 - 2 = -1.1, ES3 - 1 = -1.07). Significant decreases were found for the vigor scores in T3 when compared to T2 and T1 (p = 0.002, ES1 - 2 = 0.31, ES3 - 2 = -1.25). A significant increase was found in fatigue scores in T3 as compared to T1 and T2 (p = 0.002, ES1 - 2 = 0.43, ES2 - 3 = 0.81). A significant increase was found from T1 < T2 < T3 intension score (p = 0.002, ES1 - 2 = 1.1, ES2 - 3 = 0.2) and anger score (p = 0.03, ES1 - 2 = 0.47, ES2 - 3 = 0.33) over the study period. Total mood disturbance increased significantly (p = 0.02, ES1 - 2 = 0.91, ES2 - 3 = 1.1) from T1 to T3. Between T1-T2, significant relationships were observed between workload and changes in T (r = 0.66, p = 0.003), and T/C ratio (r = 0.62, p = 0.01). There were significant relationships between performance in RSSAbest and training load parameters (workload: r = 0.52, p = 0.03; monotony: r = 0.62, p = 0.01; strain: r = 0.62, p = 0.009). Between T2-T3, there was a significant relationship between ?% of total mood disturbance and ?% of YYIR1 (r = -0.54; p = 0.04), RSSAbest (r = 0.58, p = 0.01), SJ (r = -0,55, p = 0.01), T (r = 0.53; p = 0.03), and T/C (r = 0.5; p = 0.04). Conclusion:An intensive period of congested match play significantly compromised elite soccer players' physical and mental fitness. These changes were related to psychological but not hormonal parameters; even though significant alterations were detected for selected measures. Mood monitoring could be a simple and useful tool to determine the degree of preparedness for match play during a congested period in professional soccer.