I attend a fair number of weightlifting competitions (or I did pre-Covid). It looks as though in the current iteration of the sport, a fair number of the newer coaches have figured out the mechanics of the pull, but the mastery of the jerk is another issue. I see so many newcomers who have great difficulty with the jerk unless they are so poor at the clean that they’re not lifting heavy weights. I try to listen into the chatter as the lifter comes off the platform after a jerking failure to hear what advice is being imparted. Sometimes I hear a platitude, sometimes a word of encouragement but rarely a coaching tip that accurately deals with the technical fault. Coaching is the only way to solve problems in a timely manner.
Lack of Effective Leg Drive
Leg Drive is what propels the bar upward in the proper pathway but it is often lacking in the lifting of newcomers. The dip is often too shallow. The knees should bend to the same angle as one might employ in a vertical jump (or a proper second pull). The timing must also be precise as the descent in the dip must be controlled. Many athletes will dip too fast and actually lose contact with the bar. This results in the bar still descending as the athlete begins to drive upwards. Of course the explosive upward drive must be much faster than the dip. At the completion of the drive, the entire body must form a straight line from toes to top of the head.
Shrug at the top of the Drive
The shrug can impart speed to the bar during the drive phase. This violent action should take place simultaneously with the final extension of the legs.
Rear Leg Leaving Too Early
Many jerk drives are not completed as they are performed on one leg. This is because the rear leg in the split leaves early. Athletes and coaches need to keep in mind that foot speed is important but it is not achieved by having the feet leave early. Both feet should be involved in the jerk drive and both should leave at the same time.
Foot Strike Sequence
The positioning of the torso directly underneath the bar is achieved through proper foot strike sequence. The back foot should achieve traction first. This will drive the body of the athlete forward under the pathway of the bar. The front foot strikes shortly thereafter. This is achieved by having both feet leave simultaneously while the rear foot skims and the front foot prances.
Gripping too tightly
All of the foregoing may be coached to be performed correctly but the jerk can still fail if the arms do not straighten quickly enough. Arm locking can be inhibited if the grip on the bar is too tight. Clenching the fist will inhibit elbow extension and should be avoided. The proper action can be initiated by cradling the bar at the shoulders and not gripping tightly.
The coach needs to be aware of all of these errors and to be able to spot them as the movement is being performed. This will take a great deal of observation, but all competent coaches will make the effort and succeed at it.