ABSTRACT
The principal components of cardiorespiratory fitness (CRF) have been described beginning with the work of A. V. Hill and colleagues early in the 20th century. Cardiac function is a major component of CRF and is a key feature of the Fick equation describing VO2. The job of the heart is to generate blood pressure and flow, moving deoxygenated blood through the pulmonary vasculature for gas exchange and oxygenated, nutrient-rich blood through to the exchange vessels. Limited work has been done to identify chromosomal regions that associate with cardiac function. Inbred and recombinant inbred mouse strain distributions for cardiac function were reported as continuous in quiescent mice. The respiratory system functions to move oxygen from ambient air into blood and for excess carbon dioxide to be move from blood to ambient air, a critical component of CRF. One approach to increase oxygen-carrying capacity and CRF is living at high altitude and training at low altitude.
