Many martial arts consider breathing as an inherent part of training.

The concentration produced by deep breathing is extremely useful during various competitions. It will be better to strategize the way to target weak points of an opponent. There probability that you will panic and forget your knowledge if an opponent takes an unusual attack is very low.

Proper breathing is important for balance, and this is crucial in a tournament. Hyperventilation or constricted chest breathing may happen in stressful situations, but regular practice will train the body to keep to calm and more efficient breathing, even when you are fighting. This is more critical and dangerous than martial arts. Abdominal or diaphragmatic breathing is good for you, in particular if you are not accustomed to breathing exercises. Diaphragmatic breathing exercises help in blood circulation, and enhances the functions of the thoracic organs. Cardiovascular health, better endurance can be achieved through an easy change in breathing with help of diaphragmatic breathing exercises.

Actually, there are many types and levels of diaphragmatic breathing exercises generally used in martial arts. For example, the abdominal breathing is quite easy and even the beginners can train it. There are the advanced ones used by the people with long years of training in martial arts and meditation.
People suffering from stress can use diaphragmatic breathing exercises to cope with it.

Activate the diaphragm. You may be sitting or lying with knees bent. Do not tense up and use the upper chest for sucking air in. The shoulders should be lifted up, then let them collapse to a relaxed position. You are to repeat it 3 times. Put your hand on the chest and one hand on the abdomen to do calm diaphragmatic breathing exercises. Practice the diaphragmatic breathing exercises with your shoulders, chest and neck relaxed for two minutes. Think calm thoughts. Focus on the breath; this will take your mind away from stressful thoughts.

Small breath holds In case the diaphragmatic breathing exercises do not squash the anxiety, try small breath holds. First of all, take a small breath in via the nose; it should be followed by a breath out (only small breath). Hold your breath on the out-breath for 5 seconds, after that let go and breathe gently again. Make 10 relaxed breaths in the diaphragm. You are to repeat the 5 sec breath holds with 10 relaxed breaths for 5 minutes. This will help to override panic by activating your parasympathetic nervous system.