When you're incorporating pullups into your exercise routine, you need all the help you can get. The exercise -- which uses your upper-body strength to lift your own body weight -- requires lots of muscle power. Since muscles need oxygen to do their work, you'll need to incorporate proper breathing during the pullup in order to get maximum power. While there is a recommended cycle for exhaling and inhaling during the pullup, the important thing is just to breathe. Whatever you do, don't hold your breath, as that could lead to lightheadedness and loss of muscle strength.
Place your hands on the pullup bar in an overhand position, a bit wider than shoulder-width apart. If you put your hands in an underhand position, you are preparing for a chinup instead of a pullup.
Take a few nice deep breaths in and out, working to pull air all the way down to the bottom of your lungs. This will bring lots of oxygen into your muscles just before the tough job of doing the pullup.
Pull your body upward in the pullup. Exhale as you move upward, and push all of the remaining air out of your lungs as you reach the top of the pullup. According to Military Fitness, exhaling during the exertion portion of most workouts is the safer choice and can help prevent high blood pressure, hernia and blood vessel strains.
Lower yourself down as smoothly as you can, and take a deep breath that fills your lungs to their bottom as you move your body downward.
Exhale again as you pull yourself upward.