Lower-limb Force And Fat-free Mass Asymmetries And Their Relationships To Vertical Jump Performance

Abstract

The countermovement (CMJ) and squat jump (SJ) assess force and power production of the lower-limbs. The relationship of jumping force asymmetries to lower-limb fat-free mass (MM) asymmetries has not been well-studied. PURPOSE: The purpose of this study was to examine the relationship between CMJ and SJ performance and lower-limb MM asymmetries. METHODS: 38 Division II male lacrosse athletes performed the CMJ and SJ on bilateral force plates and their body composition was assessed via segmental bioelectrical impedance analysis. Relationships between peak and left-to-right landing and propulsive forces and MM of the lower-limbs were examined. Left-to-right peak forces were calculated as a percentage by the force plate software as ((left - right) / (left + right)) * 100. A fat-free mass asymmetry variable was manually calculated using this same formula. For both variables, a positive value indicated dominance of the left lower limb and a negative value indicated dominance of the right lower limb. The raw value of each asymmetry variable was used for correlations with other asymmetry variables while the absolute value of each asymmetry variable was used for correlations with variables that only allowed positive values. Alpha was set at 0.05. Normality was assessed with the Shapiro-Wilk test. Due to non-normality of some data, Spearman’s Rho was used for all correlational analysis. Alpha = 0.05. RESULTS: For the CMJ, peak propulsive force (PPF) was related to MM of the left (r = 0.689; p < 0.001) and right (r = 0.657; p < 0.001) lower-limb. The absolute value of the left-to-right peak landing force (PLF) was related to PLF (r = -0.351; p = 0.031). The absolute value of the left-to-right PPF was related to PPF (r = 0.322; p = 0.048). For the SJ, PPF was related to MM of the left lower-limb (r = 0.628; p < 0.001) and MM of the right lower-limb (r = 0.655; p < 0.001). Also for the SJ, left-to-right PPF was related to MM asymmetry (r = 0.386; p = 0.019). No relationships existed between jump height and any other variable for either jump. CONCLUSION: These results suggest that relationships between force asymmetries, overall force, and MM asymmetries in the lower-limbs during jumping are complex. Practically, they suggest that both force production and MM asymmetries are not clearly detrimental to jump performance.