«Cells depend on cellular
respiration as an
energy source and
during periods of food deprivation or in the absence of glucose, these cells can also resort to ketosis as an additional source of
energy.»
Cardiorespiratory fitness is a measure of how well your body is able to transport oxygen to your muscles
during prolonged exercise, and also of how well your muscles are able to absorb and use the oxygen, once it has been delivered, to generate adenosine triphosphate (ATP)
energy via cellular
respiration (cellular
respiration is a chemical process in your body's cells that converts the
energy stored in the food you eat into the ATP form of
energy that is recruited for use by your muscles).