Bench with your legs!
A.V. Samsonov and co-authors conducted a study to examine the mechanics of transferring the driving impulse from the lower limbs to the barbell of a supine athlete. Competition video analysis of athletes of various qualifications (over 30 videos in total) were used to study the one aspect of bench press technique. Specifically, the driving setup and the initial bar movement off the chest were examined (pic. 1 – in the comments of this post). The resulting analysis (pic. 1) suggests the following: at the initiation of the lift, the activation of calf and quadricep muscle groups cause the knee joints to move towards the hip with simultaneous contraction (activation) of the gluteus muscles. This causes a slight lifting and driving of the hips towards the head, while the gluteus (gluteus maximus) remain in contact with the bench.
It must be noted that those athletes who used this particular movement also made a slight upward movement with the chest. This happens because the hips, spine, chest and upper back make up a rigid frame, firmly bound by surrounding muscles. Movement of the hips upwards and towards the head arches the rest of the supporting frame towards the shoulder blades, thus causing the upwards movement of the chest. Therefore, the driving impulse is transferred towards the barbell that rests on the chest of the athlete at that moment. If the athlete is able to catch (using a powerful activation of the upper body and arm muscle groups) that driving impulse – this will help to drive the barbell upwards with increased speed at the beginning of the press. If the athlete is unable to do so – that impulse is lost. Furthermore, if the hips are driven too far upwards, the gluteus muscle will lose contact with the bench and the attempt will be disqualified.
Acquired information (A.V.Samsonov with co-authors., 2014) validates the hypothesis given by B.I. Sheiko that certain athletes with higher technical abilities, during the initial stages of the press off of the chest, seem to push off the floor towards their head. This body impulse (quantity of movements) translates via solidly structured links in the body (knees-hips-torso-spine-chest) towards the barbell during the initial press off of the chest. This allows an athlete to achieve a greater barbell velocity, which in turn will make it easier to go past any “dead spots” because the barbell will travel a greater distance before losing its velocity (it is this loss of velocity which will accurately show the start and the end of the dead spot). Not every athlete is able to engage the arms during this push off the legs and movement of the body.