I am assuming you mean a overhead barbell/dumbbell press. If so, you exhale on the hard part (pushing the weight up), and you inhale on the easy part (lowering the weight). EDIT: Not if you do the valsalva-maneuver. How you blow up a balloon. You forcefully exhale through pinched lips. It’s kind of like holding your breath while exhaling. That way you keep your abdominal area isometrically contracted for spinal support. It is not recommended for those with hypertension. You also have to be careful because if you do it too long, you can pass out -- it restricts (while increasing blood pressure) blood flow to the head (as well as other parts of the body). It can also cause an extreme drop in blood pressure at the end of a really heavy lift involving a long valsalva-maneuver (which can also cause you to pass out). So, I would recommend letting the weight down as quick as possible after a heavy lift involving a long valsalva-maneuver -- especially if you begin to feel light headed. You may be able to find out more about it if you “Google” it. Best of luck and good health!
God, I hate those. I'm doing them right now. Breathe out while your raise your arms and leg. Breathe in while you lower.
