Neuromuscular and coordination adaptations to anticipated and unanticipated side-cutting in soccer players: a dynamic systems approach

Abstract This study examined lower-limb neuromuscular and coordination adaptations during anticipated and unanticipated side-cutting using a dynamic systems approach. Ten male soccer players completed both conditions. Kinematics, ground-reaction forces, and electromyography were recorded. Muscle activity during the 50-ms pre-contact window, peak net internal hip and knee moments, continuous relative phase (CRP) coordination-pattern frequencies, and coordination variability were compared using paired t-tests and statistical parametric mapping. All analyses were exploratory, p-values were unadjusted, and the nominal significance threshold was p < 0.05. No peak hip or knee moment differed between conditions (all p ≥ 0.083). Rectus femoris and medial and lateral gastrocnemius activity showed nominal increases during unanticipated cutting ( p = 0.020–0.042), and selected hip-knee and knee-ankle coordination-pattern frequencies showed nominal differences ( p = 0.001–0.040). Coordination variability did not differ between conditions. Thus, unanticipated cutting was associated with exploratory differences in pre-contact muscle activity and coordination patterns, without detectable differences in peak joint moments or coordination variability. These measures do not directly quantify anterior cruciate ligament force, strain, or injury probability. Larger confirmatory studies with prespecified outcomes are required.