Test-retest reliability of physiological and performance responses to 120 minutes of simulated soccer match-play

This study investigated the test-retest reliability of physiological and performance responses to 120 min (90 min plus 30 min extra-time; ET) of the Soccer Match Simulation (SMS). Ten university-standard soccer players completed the SMS on two occasions under standardized conditions. Capillary and venous blood was taken pre-exercise, at half-time, at 90 and 120 min, with further capillary samples taken every 15 min throughout exercise. Core temperature (Tcore), physical (20-m and 15-m sprint speeds, and countermovement jump height), and technical (soccer dribbling) performance was also assessed during each trial. All variables except blood lactate demonstrated no systematic bias between trials (p > 0.05). During the last 15 min of ET, test-rest reliability (CV% and Pearson?s r, respectively) was moderate to strong for 20-m sprint speed (3.5%, 0.71), countermovement jump height (4.9%, 0.90), dribble speed (2.8%, 0.90) and blood glucose (7.1%, 0.93), and very strong for Tcore (1.2%, 0.99). Moderate reliability was demonstrated for 15-m sprint speed (4.6%, 0.36), dribble precision (11.5%, 0.30), plasma insulin (10.3%, 0.96), Creatine Kinase (CK; 28.1%, 0.38), interleukin-6 (24%, 0.99), non-esterified fatty acids (NEFA; 13.2%, 0.73), glycerol (12.5%, 0.86), and blood lactate (18.6%, 0.79). In the last 15 min of ET, concentrations of blood glucose and lactate, and sprint and jump performances were reduced while Tcore, NEFA, glycerol and CK concentrations were elevated (p <0.05). The SMS is a reliable protocol for measuring responses across a full 120 min of soccer-specific exercise. Deleterious effects on performance and physiological responses occur during ET.