The second sign is their breathing. Infants use only the abdominal muscles to breathe. As one ages, the breathing, if left unchecked, will rise up out of the abdomen into the chest and then into the shoulders. This rise in breathing exemplifies the deterioration of the human anatomy that comes with age and is very unhealthy. Finally, an infant's physical condition shows extreme flexibility.
Flexibility is also an important sign of good health.
Again, as we age, we become notably stiffer. This stiffness is also a sign of physical deterioration . Therefore, both Eastern medicine and the martial arts seek to understand and imitate the infant stage of human development, for it holds the keys to proper general health conditioning.