Comparing the acute effects of diagonal mobilization and Nordic hamstring curls on the vertical jump performances, static and dynamic balance, and landing stabilization in youth soccer players: a randomized multi-arm study design
Authors: Studnicki Rafał , Tomaszewicz Urszula , Hansdorfer-Korzon Rita , Kawczyński Adam 
Published: June 2024

Background
Ensuring the utilization of appropriate techniques that maximize soccer performance in terms of force, muscular power, balance, and stabilization is crucial for mitigating injury risk. Aim: The objective of this study was to compare the effects of diagonal mobilization (DM), Nordic hamstring curls (NHC), and placebo on vertical jump force and power outcomes, as well as static and dynamic balance assessed through unilateral tests, along with time to stabilization and force during landing tests conducted among young soccer players. Methods: A randomized multi-arm study design was employed. Seventy-five young male soccer players participated in this study, with an average age of 13.9 years (± 0.9), height of 174.4 cm (± 8.1), and weight of 60.6 kg (± 8.9). Participants were randomly assigned to one of three groups and were assessed both before and after the intervention. The assessment included tests such as the countermovement jump (CMJ), squat jump (SJ), single-leg standing (SLS), single-leg hold (SLLH), and the land and hold test (LH), all conducted on a force platform. Results: Significant interactions time × group were found in CMJ height (p = 0.011; \({\eta }_{p}^{2}\)<0.118), CMJ peak landing force (p=0.007; \({\eta }_{p}^{2}\)=0.129), CMJ peak power (p = 0.101; \({\eta }_{p}^{2}\)=0.062), and SJ concentric peak power (p = 0.034; \({\eta }_{p}^{2}\)=0.090). Moreover, SLS CP range anterior-posterior (p = 0.011; \({\eta }_{p}^{2}\)=0.118), SLLH time to stabilization (p<0.001; \({\eta }_{p}^{2}\)=0.299), SLLH peak drop landing force (p<0.001; \({\eta }_{p}^{2}\)=0.186), LH time to stabilization (p = 0.032; \({\eta }_{p}^{2}\)=0.041) and LH peak drop landing force (p = 0.012; \({\eta }_{p}^{2}\)=0.116). The between-group analysis showed that the placebo group exhibited significantly greater CMJ landing force compared to the DM group in the post-intervention phase (p<0.001). Additionally, the placebo group exhibited significantly smaller SJ concentric peak power compared to the DM group in the post-intervention phase (p < 0.001). The placebo group exhibited significantly greater CP medial-lateral (p=0.023) and CP anterior-posterior (p=0.006) compared to the DM group in the post-intervention phase. Also, placebo presented significantly greater CP medial-lateral (p=0.036) and CP anterior-posterior (p = 0.004) compared to the NHC group. Conclusions: In conclusion, DM revealed significant effectiveness in enhancing landing forces during both CMJ and SJ, while also improving static and dynamic balance parameters compared to the placebo. Although it did not show significant superiority to NHC in most parameters, DM exhibited significant superiority over NHC during the LH. DM appears to be a promising and effective approach for enhancing performance and minimizing injury risk parameters in soccer players.