Avoid filling the digestive tract with food or other bulk. Human Action Human action is the expression of incredibly complex and vigorous interactions of all body systems. A highly trained triathelete demonstrates the impressive ability of the human body to work skillfully, hard, and long. The basis of any exertion is the burning of fuel.
Food supplies fuel in the form of nutrients.
Inside cells, mitochondria are the basic engines that consume food molecules, release heat and store energy for the other functions of the cell. Muscle cells use the energy to contract - the basis of all human activity. During exertion, loses water and electrolytes through sweat and the lungs must be replaced. Neurotransmitters are consumed at a prodigious rate and must be re-synthesized out of nutrient substrates that are rapidly consumed. Several nutritional theories of performance enhancement have been advocated in the past several years.