The 3-D kinematics of the barbell during the snatch movement for elite Taiwan weightlifters

The subjects include four elite male Taiwan weightlifters who participated in the 2006 Asian Games qualifier for the Taiwan National Team. The four subjects were the best two weightlifters in the 62 kg and 69 kg classes, respectively. The lifts chosen for analysis were the heaviest successful attempts for each subject: a 123 kg lift for subject 1 (SI, 62 kg class), a 125 kg lift for subject 2 (S2, 62 kg class), a 131 kg lift for subject 3 (S3, 69 kg class) and a 135 kg lift for subject 4 (S4, 69 kg class). Two high-speed cameras (Mega-speed MS 1000, sampling rate: 120 Hz) were set on the left side of the lifters to film the trajectory of the left barbell. The angle between the optical axes of the two cameras was about 90°. The vertical barbell displacement was normalized at the height of the lowest position of the barbell during each catch phase to compare each lift. A small displacement of the barbell in the media-lateral horizontal direction showed that the barbell movement is almost in the sagittal plane for elite lifters. The horizontal travel range, maximum vertical displacement, drop displacement, and maximum vertical velocity of the barbell were 5.9 ± 2.6cm, 101.0 ± 4.4cm, 19.9 ± 2.3 cm and 196.7 ± 13.1 cm/s, respectively. The pathway of the barbell for S4 was significantly different from other lifters. The vertical displacement-velocity diagram showed that the four elite lifters had the same pattern for the first 60% in height from the lowest position of the barbell during each catch phase.