Evaluation of isokinetic leg strength in elite adolescent male weightlifters: Relationship with kinematics of snatch

BACKGROUND: The purpose of the study was to examine the changes in isokinetic leg strength in different angular velocities in elite male adolescent weightlifters and to assess the association between isokinetic leg strength and the snatch lift kinematics. METHODS: Junior national team weightlifters (N.=9) participated in the study. To obtain the barbell kinematics, maximum snatch lifts were recorded and digitized using motion analysis system. The mechanical work done on the barbell and power output were calculated. Concentric peak torque of hamstring (H) and quadriceps muscles (Q) of the dominant (D) and non-dominant leg (ND) was evaluated using Cybex NORM at 30, 60, 90, 120, and 180°/s. RESULTS: Relative H and Q peak torque significantly decreased at 120 and 180°/s with respect to 30, 60, and 90°/s in, whereas, in ND, a significant decrease was only observed for 180°/s. H/Q ratio was in the range of 51-56% and 54-57% for D and ND, respectively. Positive and negative correlations were found between relative H strength in ND and barbell velocity during the first pull at 120 (r=0.74; P<0.05) and 180°/s (r=0.83; P<0.01) and between H strength in ND and relative mechanical work during the second pull at 90 (r=-0.70; P<0.05) and 120°/s (r=-0.72; P<0.05), respectively. CONCLUSIONS: The results revealed that isokinetic knee strength was maximal at angular velocities up to 90°/s in adolescent weightlifters. Only H strength in ND correlated with biomechanics of the first pull of the snatch at fast velocities.