Is it bad to breathe slowly or fast?

Answer 1

Bad is such a value-laden word...

Sounds like you might want running advice. Slow and deep or quick and shallow. Which is going to provide you with better oxygen transfer sounds like the question. Recognize that you have a biological dead air space where no respiration occurs. If you breathe shallowly and don't take in more than about a pint at a time, you will suffocate because fresh air is not getting into your lungs.

When you breathe deeply, you are getting the maximum quantity of fresh air with oxygen into contact with lung tissue. Deep breathing is, therefore, more efficient. While you are training yourself to breathe deeply, practice breathing through the nose rather than through the mouth. Your nose will condition the air and prepare it for the lungs.