Collins, J., Crawford, T. & Collins, K. 2022 Relationship between internal and external training load metrics on neuromuscular performance. World Congress on Science and Soccer.
Measuring neuromuscular performance (NMP) in soccer is of interest to practitioners due to its negative effect on performance. Reductions in NMP can be seen 48 hours post-match and thus aiding practitioners to alter periodization schemes to include recovery modalities. The aim of the current study was to examine the potential relationship between internal and external training load metrics and NMP during multiple training windows prior to matches. Thirty-five male professional soccer players from a single squad in North America participated in the study during the 2021 season. Players performed a countermovement jump (CMJ) as a predictor of neuromuscular fatigue. Tests were conducted the day prior to a game (Match Day-1). Players were familiarized with the CMJ test prior to the onset of the study. Internal and external training load was measured at every training session and games. The effect of a seven, fourteen and twenty-eight day accumulated load were analysed against changes in CMJ measures. Data was analysed using a multiple regression where changes in mRSI, jump height and time to take off were the dependent variables. Statistical significance was set at p<0.05 with 90% confidence intervals. A relationship was found between total distance and accelerations with NMP in a 7-day training window. High-speed running, training load and total distance had a relationship with a decrease in NMP over a 14-day training window while increases in sprint distance resulted in lower NMP across a 28-day training window. Highlighting that changes across internal and external training load measures can have an impact on NMP across several different training periods. The current study has displayed a relationship with high intensity, mechanical training load and neuromuscular performance. While a relationship was observed, further research is needed in the area of measuring NMP in team sports and in particular in its effect on match physical performance and outcomes.