Breathing is an important part of exercising. Although how you should breathe is somewhat dependent on the type of activity, when it comes to anaerobic strength training the rule of thumb we always follow is to exhale on the exertion. Put more simply, breathe out while your muscles are contracting and breathe in when they are relaxing.
When you inhale, your muscles tend to relax, which is why your massage therapist or trainer tells you to take deep breaths when they are massaging or stretching you. Since we want the opposite effect during contraction, we exhale during the exertion part of the exercise.
The work of breathing isn't just done by your lungs. It involves many of the muscles in your upper body. When you exhale those muscles all contract, and that helps you tighten your core. Since using your core in everything is the single most important aspect of our Fitness For Life philosophy, exhaling while doing the exertion part of a motion will further help you achieve that stability.
To help our clients remember the proper breathing technique we have always used the example of tennis players and other athletes who like to grunt when doing something explosive, like hitting a ball or kicking a bag. The grunt isn't just a sound effect to intimidate your opponent. It also happens to be an exhale!
Not surprisingly recent science backs up our philosophy. In a study of tennis players published in the Journal of Strength and Conditioning Research, researchers at the University of Nebraska found players hit the ball significantly faster when grunting.