Olympic weightlifting encyclopedia 24

The Second Phase of the Pull: Preliminary Acceleration

Most athletes separate the bar from the platform in a relatively smooth fashion and then begin to accelerate the upward motion of the bar. During this phase of the pull, the bar travels toward the lifter, and the center of gravity of the lifter shifts toward the heels. Throughout most of the preliminary acceleration phase, the angle of the back in relation to the platform remains essentially the same as at the moment of bar separation, an average of 30 in relation to the platform in the snatch and 32’ in the clean; toward the end of this phase, the angle of the torso begins to increase (1.e., the torso begins to straighten). The hips rise, while the torso of the lifter travels upward and forward so that the shoulders move well in front of the bar. If the head did not begin in a vertical position it often begins to assume such a position during this phase of the pull. The acceleration phase typically begins with the knees at an angle of between 80 and 110 and ends when the knees have reached an angle of 145 to 155. The angle in the snatch tends to be at the higher part of this range, and the angle in the clean at the lower part of this range; athletes with a longer torso and shorter legs tend to have the lower knee angles in these ranges and athletes with the opposite conformation have larger knee angles. Because the legs straighten more in the clean than in the snatch, the torso shifts forward more in the clean. The shins achieve an essentially vertical position at the end of this phase. The bar is usually at about 31% of the athlete’s height in the clean and at 35% in the snatch (just above the knees in the clean and approximately at the lower third of the thigh in the snatch).

As the preliminary acceleration is executed, the centers of gravity of the bar and athlete move closer together than they were at the start of the pull. The bar moves toward the athlete less in the clean than in the snatch, but the athlete moves toward the bar to a greater extent. (The further apart the centers of gravity of the body and the bar are at the start, the more the bar will shift at this stage in the pull.) This phase of the pull generally takes about half a second (the time involved in the snatch is usually very slightly less than for the clean). The velocity achieved by the bar at this point is approximately 1.5 meters per second in the snatch and 1.2 meters per second in the clean (taller lifters tend to generate somewhat greater bar speeds and shorter lifters somewhat lower). By the end of this phase, the bar has shifted as much toward the athlete as it will at any point in the pull (4 to 12 cm in the snatch and 3 to 10 em in the clean, the bar shifting a greater distance for taller lifters).