Smartphone-Assessed Single-Leg Deadlift Stability is Associated with Sprint Velocity in Youth Soccer Players: A Cross-Sectional Study

a high level 3,4 .From a physical standpoint, competitive football players require a combination of high levels of muscle strength/power, change-of-direction (COD) speed and velocity in short-distances 5 reported superior neuromuscular performance in elite football players compared to their sub-elite and recreational counterparts 6 .These findings suggest that strength and power capabilities are critical determinants of performance in competitive football particularly at the elite level, moreover, when combined with adequate core stability, these qualities may enhance a player's ability to maintain balance while dribbling, shielding the ball from opponents, or performing sudden changes of direction 7 .Trunk muscle strength and stability play a crucial role in transferring energy between the lower and upper body during intermittent movements, such as accelerations, AbstractObjectives: To investigate the relationship between core stability and neuromuscular performance (i.e., sprint velocity and change-of-direction speed) among adolescent male football players.Methods: In this cross-sectional study, sixteen high-level male football players were divided into higher and lower core stability groups based on their performance in a partial range single-leg deadlift (SLD) test, assessed using a smartphone application (OCTOcore© app).Neuromuscular performance was assessed with a 30-m maximal sprint test (with 5-m split intervals) and a V-cut test, and these outcomes were correlated with SLD test results.Results: Statistically significant differences were observed between higher and lower core performance groups in the SLD test (p = 0.001) and between SLD non-dominant and 30-m maximal sprint test (p = 0.001-0.005),while no differences were founded between SLD performance and V-cut test (p>0.05).A large correlation was found between non-dominant SLD and 10-m sprint performance (r = 0.765, p = 0.001), while moderate correlations were observed for the 15-, 20-, 25-, and 30-m sprints (r = 0.508-0.562,p = 0.023-0.044).No significant correlations between SLD performance and the V-cut test (p>0.05).Conclusion: Core stability appears to be positively associated with sprint performance (0-30 m) but not with change-of-direction speed, suggesting that it plays a greater role in linear acceleration than in multidirectional tasks.