(11) GETTING STRONG IS THE RIGHT MOVE - AN INSIGHT INTO PROFESSIONAL LOWER LEAGUE ENGLISH SOCCER PLAYERS: A BAYESIAN APPROACH

Purpose: Maximal and rapid force production are important attributes required by soccer players to complete athletic tasks, a force relative to the mass being accelerated dictates acceleration, with the duration of force application (i.e., relative impulse) determining velocity. However, no study has reported the effect of relative peak isometric mid-thigh pull (IMTP) force on jump characteristics within professional English soccer players. Therefore, the purpose of the present study was to determine the effect of strength on countermovement jump (CMJ) performance in professional English soccer players. Hypothesizing that stronger athletes would have higher CMJ performance. Methods: Seventy-six professional lower league soccer players (mass: 82.5 ± 8.2 kg, height: 1.80 ± 0.07 m, age: 25.8 ± 4.3 years) performed three trials of the CMJ and IMTP as part of pre-season testing, using force plates. The mean of the three trials was taken for analysis. Players were categorized as strong and weak using the groups average IMTP relative peak force. A series of one-way Bayesian independent t-tests were performed to determine the difference between strong and weak groups for anthropometrics, IMTP relative peak force and CMJ outcome, driver and strategy metrics. Bayes factors (BF) were interpreted as < 1 = evidence supporting the null hypothesis, ~1 = no clear evidence to reject or support the null hypothesis, 1.00-3.00 = weak evidence supporting the hypothesis, 3.01-10.00 = moderate evidence supporting the hypothesis. The prior was set at the default BF10 = 0.707. Hedges g effect sizes and 95% confidence intervals (95CI) were also reported. Results: Participants were categorized into strong (n = 37) and weak groups (n = 39) based on being above or below the average of the sample (33.41 N/kg). There was no clear evidence for jump height and relative peak propulsive force (N/kg) to reject or support the null hypothesis (Table 1). Anecdotal evidence supporting the hypothesis was observed for relative force at minimum displacement and relative average propulsive force (Table 1). Moderate evidence supporting the hypothesis was observed for relative average braking force and modified reactive strength index (mRSI) (Table 1). Anecdotal-strong evidence supporting the null hypothesis was observed for body mass, jump momentum, countermovement depth, time to take off (TTT) (Table 1). Conclusions: Stronger soccer players display enhanced kinetics during the braking phase potentially leading to a favorable jump strategy (i.e., higher mRSI, due to a lower TTT) for the same outcome (i.e., jump height). Weaker athletes were heavier than stronger athletes and indicated a reduced ability to decelerate their mass effectively during the CMJ resulting in increased time to take off and countermovement depth to achieve a similar outcome. Practical Applications: English soccer players and relevant practitioners should prioritize relative strength to enhance braking phase kinetics and overall jump performance. Acknowledgements: NONE