Breathing is considered the "strategy" in qigong. In small circulation you may use either of the so-called Buddhist or Daoist breathing strategies. Buddhist breathing is also called "normal breathing" (zheng hu xi), while Daoist breathing is called "reverse breathing" (fan hu xi). In Buddhist breathing, you expand your abdomen as you inhale and contract it as you exhale. Daoist breathing is just the reverse.
Buddhist breathing is generally more relaxed than Daoist breathing. Although Daoist breathing is tenser and harder to train, it is more efficient in expanding the guardian qi (wei qi) and in martial applications. This point can be clarified if you pay attention to the everyday movements of your abdomen. Normally, if you are relaxed or not doing heavy work, you will notice you are using Buddhist breathing. However, if you are doing heavy work and exerting a lot of force, for example pushing a car or lifting a heavy box, then you will find your abdomen tenses and expands when you push or lift, which is Daoist breathing. It is suggested that beginners start with Buddhist breathing. After you have mastered it, you should then practice Daoist breathing. There is no conflict. After you practice for a while, you will find you can switch from one to the other very easily. Click to learn how Chinese medicine treats Myocardial Infarction.