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Medicina dello Sport 2022 December;75(4):477-87

DOI: 10.23736/S0025-7826.22.04190-4


language: English, Italian

The effects of training with unstable surfaces on the strength and inter-limb asymmetry values in young soccer players


University of Foggia, Foggia, Italy


BACKGROUND: The inter-limb asymmetry refers to the strength performance of one limb with respect to the other. It differs from muscular imbalances, which represent an alteration in the strength relationship between agonist and antagonistic muscle pairs. This asymmetry seems to significantly affect performance but above all it seems to represent an injury risk factor. The study aims to analyse and understand the inter-limb asymmetry values in the young soccer players. The study also verifies whether neuromuscular training on unstable surfaces provides an effective plan able to reduce functional asymmetries and allows the strength performance increase.
METHODS: Thirty-seven young male soccer players (all movement players) from youth national team in the 2020/21 season (14.31±0.64 years, weight: 48.96±6.72 kg; height: 161.1±9.2 cm, age training: 8.1±1.2 years) have been randomly divided into experimental group, EG (N.=17) and control group, CG (N.=20). The EG completed a total of 16 training sessions directed at balance and neuromuscular training on unstable or small surfaces: two 30-minute sessions/week over an 8-week period. The CG followed an identical training schedule, but training sessions consisted of soccer-specific drills only. The performances were assessed in the hop test, side-hop test, triple-hop test and crossover-hop test to quantify percent asymmetries in lower-limb strength before (T0) and following (T1) training.
RESULTS: The data analysis returns the highlights significant intergroup results (T0 vs. T1): the one-leg hop test left limb (P=0.05, d=-2,67), the Hop test asymmetry score (%, P=0.0005, d=10.77), the side-hop test asymmetry score (%, P=0.0005, d=4.25), the triple-hop test right limb ( P=0.0005, d=-6.40), the triple-hop test left limb ( P=0.0005, d=-7.32), the triple-hop test asymmetry score (%, P=0.0005, d=6.96), the crossover-hop test left limb (P=0.05, d=-2.04), the crossover-hop test asymmetry score (%, P=0.0005, d=-4.12).
CONCLUSIONS. The neuromuscular training on unstable surfaces seem to respond effectively to two needs of the young soccer player: the injury prevention, by reducing the strength asymmetry values, and increasing the lower limb explosive strength values.

KEY WORDS: Soccer player; Exercise; Postural balance

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