Effects of Dynamic Core Stability Training as an Adjunct to the FIFA 11+ Program on Dynamic Knee Valgus, Single-Leg Athletic Stability, and Isometric Hip Strength in Amateur Soccer Players: A Randomized Controlled Trial

Background and Objectives: Proximal trunk and hip control during dynamic tasks is a key modifiable determinant of dynamic knee valgus (DKV) in soccer players. This study investigated the effects of adding dynamic core stability training (DCS) to the FIFA 11+ warm-up program compared with the FIFA 11+ on DKV, single-leg athletic stability, and isometric hip muscle strength in amateur soccer players. Methods: A single-blinded, parallel-group randomized controlled trial was conducted on 40 amateur soccer players (mean age 16.6 ± 3.1 years). Participants were randomly allocated to either DCS+FIFA 11+ training or FIFA 11+ alone, with both interventions performed three times per week for 8 weeks. DKV, single-leg athletic stability and isometric hip strength was assessed at the baseline, 4 weeks, and 8 weeks. Data were analyzed using linear mixed-effects models to examine Group, Time, and Group × Time effects, with participant included as a random effect. Benjamini–Hochberg false discovery rate adjustment was applied to the Group × Time comparisons. Results: Significant Time effects were observed for all outcomes. After Benjamini–Hochberg correction, significant Group × Time interactions were observed for left-leg athletic stability (adjusted p < 0.001; ηp2 = 0.243), left hip abductor strength (adjusted p = 0.025; ηp2 = 0.125), and right and left hip external rotator strength (adjusted p < 0.001 and <0.001; ηp2 = 0.302 and 0.404 respectively), with greater improvements in the DCS+FIFA 11+ group. Both groups demonstrated reductions in right and left DKV over time; however, Group × Time interactions were not significant for either DKV measure. Conclusions: Adding dynamic core stability training to the FIFA 11+ was associated with greater longitudinal improvements in left-leg athletic stability and hip muscle strength outcomes, particularly left hip abductor and bilateral hip external rotator strength. Supplementing the FIFA 11+ with DCS training may provide additional benefits for selected aspects of lower-extremity movement control and proximal muscle strength in amateur soccer players.