I find this highly confusing because I've read in some places to do the "J Lift" but others saying push in a straight line. I've also read that you should use the "J Lift" when you are struggling with your weight only, but timing is critical. Maybe I should just experiment and see which I can use to push more weight with?
4 – Push the bar in a straight line.
Try to push the bar toward your feet. The shortest distance between two points is a straight line, right? Then why in the world would some coaches advocate pressing in a "J" line toward the rack? If I were to bench the way most trainers are advocating (with my elbows out, bringing the bar down to the chest and pressing toward the rack) my barbell travel distance would be 16 inches. Now, if I pull my shoulder blades together, tuck my chin and elbows, and bring the bar to my upper abdominals or lower chest, then my pressing distance is only 6.5 inches. Now which would you prefer? If you want to push up a bar-bending load of plates, you'd choose the shorter distance.
Here's another important aspect of pressing in this style. By keeping your shoulder blades together and your chin and elbows tucked, you'll have less shoulder rotation when compared to the J-line method of pressing. This is easy to see by watching how low the elbows drop in the bottom part of the press when the barbell is on the chest. With the elbows out, most everyone's elbows are far lower than the bench. This creates a tremendous amount of shoulder rotation and strain.
Now try the same thing with the elbows tucked and shoulder blades together while bringing the barbell to your upper abdominals. For most people, the elbows are usually no lower than the bench. Less shoulder rotation equals less strain on the shoulder joint. This means pressing bigger weights for many more years. I've always been amazed at trainers that suggest only doing the top half of the bench press, i.e. stopping when the upper arms are parallel to the floor. This is done to avoid the excess shoulder rotation. All they have to do is teach their clients the proper way to bench in the first place!