(7) SINGLE JOINT ISOMETRIC HAMSTRING STRENGTH IN PROFESSIONAL SOCCER PLAYERS: NORMATIVE BENCHMARKS AND POSITIONAL DIFFERENCES

The hamstrings' ability to produce a large force to overcome the high angular velocities and momentum of the shank during the terminal swing phase of running is crucial to mitigating injury risk. PURPOSE Therefore, the purpose of this study was to assess professional soccer players with two isometric hamstring strength assessment, providing normative benchmarks and positional differences. METHODS 79 senior professional men’s soccer outfielders (age; 24.2 ± 5.1 years, height; 183.6 ± 5.8 cm, mass; 81.5 ± 8.1 kg) participated within the present study. Three trials of two different single joint isometric hamstring strength assessments using force plates were performed as part of pre-season testing (June 2023). Long lever and short lever tests were performed in a supine position with the knee and hip positioned in 90° of hip and knee flexion (90:90) or 30° hip and knee flexion (30:30). Data was collected using Hawkin Dynamics (HD) force plates and analysed using HD software. Participants were fixed at the hip by the assessor, removed all footwear and hands positioned at the shoulders. Limb dominance was categorised on kicking preference; dominant (DL) and non-dominant limb (NDL). Acceptable reliability was assessed using coefficient of variation percentage (CV%) and intraclass correlation coefficients (ICCs). Reliability was interpreted based on the associated 95% confidence intervals (CI). Standardised T-scores (scaled from 0-100) were calculated for each test based off the mean and standard deviations and used to create performance bands with a qualitative description (ranging from extremely poor to excellent) and a traffic light system for ease of data interpretation for coaches and athletes. A series of repeated measures analysis of variance (ANOVA) with Bonferroni post-hoc analysis and Cohen’s d effect sizes used to examine positional differences between outfield players. All statistical analysis was completed using JASP statistical software. P value was set at 0.05. RESULTS A non-significant mains effect was observed between test positions (p>0.05, η²), with trivial-small, yet non-significant pairwise differences between positions for each test (p>203, d = 0.01-47). Strikers were the weakest across all positions, whereas midfielders were stronger on the NDL limb for both the 90:90 and 30:30 and defenders were stronger on the DL. CONCLUSIONS There were minimal differences between outfield positions in relative isometric hamstring strength in the 30:30 and 90:90 assessments. PRACTICAL APPLICATIONS Despite meaningful differences in movement characteristics between positions, they all exhibit similar levels of isometric hamstring strength. This could present an issue for midfielders or attackers who will commonly perform greater volumes of high-speed running and sprinting, which is a task commonly associated with hamstring strain injuries.

Acknowledgements: None