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.
A pump actually places the myocytes under tension due to a swelling effect exerted on the muscle cell membranes, which is theorized to lead to greater muscle growth due to the perceived threat on the cellsâ ultrastructures. In other words, metabolic stress is effective at creating tension from the inside out in the individual muscle cells. As a matter of fact, fiber damage can induce cell swelling just as the pump can, and this swelling can last for several days.