An important aspect to consider while strength training is breathing technique. Typically while weight training an athlete is taught to exhale while either pushing or pulling weight against gravity and to inhale while lowering or returning the weight to the start position.
The pushing or pulling of weight is known as the positive or concentric contraction, and the lowering or returning the weight to start position is known as the negative or eccentric contraction.
For most weight resistance based exercises the negative or eccentric motion should be performed at a slower speed than the positive or concentric contraction, which in turn makes breathing while doing this somewhat difficult. While performing the slower paced negative repetition only taking one breath in can seem a bit much, resulting in increased labor during breathing. After several reps into the exercise it starts to feel as if you are working as hard just to breathe, resembling hyperventilation.
Instead of only taking in one giant long-winded breath during the negative part of the movement, try taking three relaxed breaths, first inhaling, then exhaling, and then inhaling again. As you start the positive or concentric phase of the movement, then you should start to exhale slowly as you either push the weight away from you or pull the weight towards you. This allows you to breathe more in sync with the movement being performed and helps keep a good tempo throughout the exercise.
However there are times when you would only want to take two breaths during each rep and that would apply more to speed based movements, where you still perform controlled negatives but the exercise is done at a faster rate, such as a speed based bicep curl, breathing in once as you lower the weight and exhaling once as you raise the weight.
For some exercises you are encouraged to hold your breath at some point. This is known as “maintaining intra-abdominal pressure”. The idea behind this breathing technique is to maintain a pocket of air, which in turn acts like an air cushion between your lower spine and abdominal wall. This aids in helping the lower spine from excessively curving inward with increased loads and reducing the likelihood of injury to the lower back.
A good example of when to use this breathing technique would be while performing barbell squats. The weight of the bar will create an excessive load the axial spine especially at the bottom end of the squat, the point at which you would have the greatest amount of hip and knee flexion, and are in the actual squat position. It would be at this point that you would want to hold your breath and then slowly exhale as you push upward and assume an upright standing position. Subjects with high blood pressure however are not encouraged to breathe in this manner as it could put them at a greater metabolic risk.
Jon Torerk, CSCS