The Dose-Response Effects of Dissociation Training on Measures of Neuromuscular Control during Performance Screening in Male Youth Footballers

AIMS: Movement screens purportedly identify compensatory kinematics that predispose athletes to injury (Kiesel et al., 2011). The efficacy of assessing select competencies and prescribing remedial training based on screen outcomes however remains equivocal. The Foundation Performance Matrix Screen© (FPMS) supposedly profiles injury risk, subsequently directing its independent motor control Dissociation Training (DT) (Mottram and Comerford, 2008). However, there appears to be no research evidencing that DT can improve FPMS score or reduce injury. Therefore this study aimed to investigate the doseresponse of DT on kinematic and kinetic measures of neuromuscular control in male elite academy footballers. METHOD: The dose-response to DT therefore remains to be established. With institutional ethics approval, elite U15/16 and U17/18 male academy footballers comprised group one (n = 6) (G1) and group two (n = 8) (G2) respectively. G1 performed DT 1x week while G2 performed DT 3x week over eight weeks. Centre of pressure (CoP) total, anterior-posterior (X) and medial-lateral (Y) displacements (cm), sway velocity (cm∙s -1) and ellipse area (cm2) were recorded from participants’ non-dominant leg during a single leg stance test (SLST) and Y balance test™ (YBT). Force platform time to stabilisation (TTS), peak vertical ground reaction force (PVGRF) and loading rates were recorded from a 20cm bilateral drop jump landing (DJL). The FPMS and YBT were scored according to respective guidelines. All tests were performed barefoot. Cohen’s d effect size (ES) was calculated from differences in means. RESULTS: Small ES for G1 (ES -0.180; 95% CI, −1.94 - 0.60) and G2 (ES −0.136; 95% CI, −0.12 - 1.62) FPMS scores were observed. Large ES for DJL loading rates (ES -1.89, 95% CI, 0.046 - 0.079) and YBT normalised anterior reach (ES 1.416, 95% CI, 66.30 - 73.29) were observed for G1 compared to G2 where trivial (ES 0.072, 95% CI, 0.067 - 0.095) and moderate effects (ES 1.104, 95% CI, 66.84 - 72.90) respectively, were observed. The magnitude of change for G1 was consistently greater for all DJL and YBT measures. Furthermore, SLST performance for G1 improved for all CoP measures whereas G2 decreased. CONCLUSION: The measures used to assess neuromuscular function indicate eight weeks DT had meaningful effects on neuromuscular control, however, the magnitude of effects were greater for G1 than G2. As SLST, YBT and DJL indicated greater effects and are all proposed to predict injury, they could be a suitable surrogate marker for assessing the effects of DT. These findings also suggest that a lower dose of DT is sufficient provided training is individualised.