Breathing is an important part of the execution of any maneuver in American Kenpo. Short Form One is no exception. One must learn the importance of breath and how it affects their performance.
One bad habit that numerous beginner to intermediate students sometimes pick up is the holding of their breath during the execution of maneuvers. This should be corrected by having the practitioner concentrate on smooth and relaxed breathing. The only emphasis in one's breath should be at the anticipated point of contact of the block. This emphasis of breath should be for the purpose of helping to focus one's energy. Holding one's breath can lead to Constipated Motion - i.e. motion that is not fluid and/or smooth, but rather staccato and/or stiff in nature.
The kiai is a form of focusing one's breath by creating an audible sound with the breath through tightening of the abdominal muscles, thus forcing the breath to exhale. Some instructors teach using kiais to help students focus their breath with their maneuvers. Although Short Form One does not specifically contain any kiais in it's standard execution, it is not an incorrect nor bad teaching tool. On the contrary, it can be used to help a student correct breathing issues, along with teaching the purpose of tightening muscles in anticipation of absorbing an oncoming strike to the body. It can also be used as an 'attention getter' when executing a form in competition.