Everyone knows that strength training or weight lifting is an important component of exercise, or at least you hope so. However, how to strength train correctly when you actually decide to do it is another story. In my experience, improper breathing is one of the most common mistakes people make during a strength training workout. I am going to explain how to breathe during strength training in two ways. First, and possibly a bit more confusing, I will discuss strength training breathing as it is associated with gravity. Gravity as you know is the force that keeps us all on the ground and brings us back to the ground if we leave it. But did you know gravity is what makes strength training a possibility? Gravity pushes on us from above with a force of about 9.8 m/s^2 which means you have to fight that force any time you attempt to move dumbbells, medicine balls, barbells, and any other strength training equipment up. Breathing correctly comes into play during that attempt to move that equipment up. When you strength train, anytime you are fighting gravity you should be blowing air out and when you are working with gravity you should be breathing air in.
If you are still attempting to wrap your head around the gravity example of strength training breathing, don't worry, my second method of explanation starts right now. Think of a simple exercise like a dumbbell biceps curl. If you are unsure what a biceps curl looks like click here. Biceps curls, and every other strength training move, have two phases, contraction and relaxation. When the weight you are using for a biceps curl is down and your arms are straight and extended, little to no work is being done and this is called relaxation. When you move the weight up and bend your arms at the elbow, work is being done and this is called contraction. In all strength training exercises, when work is being done (contraction), breathe air out. When you are lowering weight to a point where no work is going to be done (relaxation), breathe air in.
You should now be a strength training breathing expert, but if you are still confused after those examples, leave me a question in the comment box and I will remedy your confusion.