There are certain co-ordinate curves, beautiful, spiral, rhythmic, in a normal and healthy human being. These curves depend upon this expansion of the chest.
All the best gymnastic exercises centre in the development of activity in the muscles concerned in keeping the chest elevated and harmoniously expanded.
When we study the expression of this part, we find that it reveals energy and courage and all the noble, positive emotions of a human being.
A passive chest expresses indifference, inactivity, fear, discouragement, a sense of weakness, unwillingness to awake and rise up to meet emergencies. A sunken chest, accordingly, is an indication of a tendency to disease, simply because it expresses a negative mental state or one favorable to the reception of abnormal conditions.
The expansion of the chest, on the contrary, reveals that happy acceptance of life, that active, energetic determination to control abnormal conditions which will ward off all disease and eliminate all failure.
This expansion of the chest, as we can see, is one of the most elemental actions of expansion of the human being. We shall observe later that this activity is directly concerned with erect posture. All actions in a normal condition co-operate or co-ordinate. This expansion frees the respiratory muscles and all the vital organs, gives man command of the elemental action of his body as a whole; that is, his erectness expresses higher emotions and experiences.
An exercise implies co-ordination.
An organism exists only by virtue of certain co-ordination of parts. Training improves and extends this co-ordination.
Co-ordination is the simultaneous union of many different elements or actions in different parts of the body.
An exercise is rhythmic.