From AikiWiki - AikiWeb Aikido Information
[edit] Kokyu: 呼吸
Lit: Breath. Part of aikido is the development of "KOKYU RYOKU", or "breath power." This is the coordination of breath with movement. A prosaic example: When lifting a heavy object, it is generally easier when breathing out. Also breath control may facilitate greater concentration and the elimination of stress. In many traditional forms of meditation, focus on the breath is used as a method for developing heightened concentration or mental equanimity. This is also the case in aikido. A number of exercises in aikido are called "KOKYU HO," or "breath exercises." These exercises are meant to help one develop KOKYU RYOKU.