Relationship between internal and external training load metrics on neuromuscular performance

The study investigates the association between internal and external training load on neuromuscular performance (NMP) on elite soccer players. Thirty-five professional soccer players from a single squad participated in the study. Players performed a countermovement jump as a surrogate measure of NMP. Tests were conducted the day prior to a game. Internal load was measured using session rating of perceived exertion, with external load analysed through 10 Hz GPS units. Measures of external load included total distance, high-speed running, sprint distance, accelerations and decelerations. Measures of NMP were RSI-mod, time to take off (TTTO) and jump height (JH). Within a 7-day training window, total distance (ES = 0.03) and acceleration (ES = 0.04) had a significant interaction with NMP. Within a 14-day training window, RSI-mod and TTTO had a significant interaction with internal load (ES = 0.01; ES = 1.54) and high-speed running (ES = 0.02; ES = 1.44), JH and total distance had a significant interaction (ES = 1.867). For the 28-day training window, JH and sprint distance had a significant interaction (ES = 1.86). Practitioners should use a multi-metric approach with measures of NMP and loading to gain a greater understanding of their athletes.