When doing push exercises, such as the bench press and military press, what is should the angle of the wrist be to prevent injury? Should the wrist be straight or should it be bent like the following image?
Here is a good article about biomechanical explanation of bench press with references at the end. To make the long story short; Grasp the barbell with an opposing thumb grip (thumbs wraps around the bar) with your hands shoulder-width or slightly wider than shoulder-width apart. An opposing thumb grip provides more security and control of the barbell. Grasp the bar with the wrists positioned directly under the bar. This position helps avoid hyperextension of the wrists. Retract your shoulder blades (scapulae), bringing them closer together.