1 Chemically, ATP is an adenine nucleotide bound to three phosphates. 2  There is a lot of energy stored in the bond between the second and third phosphate groups that can be used to fuel chemical reactions. 3  When a cell needs energy, it breaks this bond to form adenosine diphosphate (ADP) and a free phosphate molecule.
calf muscle pump. calf muscle pump. an action of the calf (soleus) muscles in which the muscles contract and squeeze the popliteal and tibial veins, forcing the blood in those veins to move upward toward the heart. Also called soleus pump.
Adenosine Triphosphate (ATP) is the immediate source of (chemical) energy for muscle contraction. Very little ATP is stored in muscle fibres (= ' muscle cells '), only enough to power muscle contractions for a few seconds.The ATP in muscles must be constantly replenished as it is used for various processes. Glycolysis is the break-down of glucose molecules. Glucose molecules can reach muscle tissues via blood circulation. They can also be produced within muscle cells by the breakdown of glycogen molecules (glycogen being the form in which glucose is stored muscles). 3. This process. so it is described as aerobic.