Background Soccer, sports asymmetric, requiring different loads to the lower limbs as the player uses separately one leg to kick and the other one to jump and landing; in literature are studies that have described this asymmetry in terms of strength (Samadi et al., 2009; Rahnama et al., 2005) or ground reaction force in the landing (Sannicandro, 2008).
Objective Analyzing the relationship between asymmetry of the strength of the lower capacity and ability to manage tasks in one-leg-standing balance in professional players.
Design Descriptive research (correlation study which investigates the relationship between variables).
Setting Soccer elite division in the off season.
Participants 29 soccer players (25.3±2.7 year, 180.1±2.6 cm, 78.5±2.2 kg).
Assessment of risk factors The maximal strength, the explosive strength and the balance test can be considered as indicators for to determine both the functional asymmetry of lower limbs both potential risk factors for soccer player.
Main outcome measurements For each leg was assessed maximal strength (1RM) using a leg press (Technogym, Italy), explosive strength through hop test, the ability to balance by tilting platform electronics (DEB, Delos Italy). This instrument has provided the percentage of time that the player has complied with the assigned range of motion of ±2°.
Results The assessment of maximal strength, explosive power and the balance returned respectively asymmetry averaged 9.9±7.2% to 6.6±5.3% and 11.4±3.2%. There was a correlation between 1RM and leg hop test for left and right respectively equal to r=0.55 and r=0.53 (p<0.01), a correlation between test and hop balance equal respectively to r=0.49 and r=0.47 (p<0.01).
Conclusion The study describes the functional asymmetries of the lower limb in soccer players in relation to 1RM, the explosive strength and balance tasks in one-leg-standing. The correlation between values of explosive strength and balance tasks would suggest a functional relationship between two ability, as already hypothesised in literature (Gstöttner et al., 2009).