Repeated small-sided games induce load-dependent changes in strength and neuromuscular indicators in U17 male soccer players

We quantified set-by-set acceleration – deceleration exposure during repeated 2v2 small-sided games (SSGs), assessed acute pre – post changes in selected neuromuscular and strength markers, and tested load – response associations. Ninety players completed 8 × 2-min 2v2 bouts with 2-min passive recovery. Total and high-intensity accelerations (Acc)/decelerations (Dec) were derived per set; pre – post testing assessed quadriceps concentric and hamstring eccentric peak torque (60°·s−1), functional H/Q (H_ecc/Q_con), relative leg stiffness (RLS), and reactive strength index (RSI). Total Dec varied across sets (F(7,623)=3.58, p < 0.001) and declined (slope = -0.295 counts·set−1, p < 0.001); high-intensity Dec also varied across sets (F(7,623)=3.67, p < 0.001). Post-SSG, hamstring eccentric torque decreased (Δ = -8.637 N·m; dz = -1.74; p < 0.001), functional H/Q decreased (Δ = -0.028; dz = -1.03; p < 0.001), and RLS decreased (Δ = -2.363 kN·m−1; dz = -2.93; p < 0.001), while RSI increased (Δ = 0.032; dz = 2.37; p < 0.001). In simultaneous multivariable models, accumulated high-intensity Dec independently predicted greater RLS reductions (β = -0.416, p < 0.001; adj R2 = 0.252) . In conclusion, repeated 2v2 SSGs induce acute changes in selected neuromuscular and strength measures, and accumulated high-intensity braking and propulsion loads best explain these acute neuromuscular shifts.