a muscle pump is nothing more than osmosis. hate to bust your bubble dude. its just that. during an exersice, your muscle tissue is screaming for more energy in this case glycogen, which in turn is needed to continue to produce and desphosphorylate ATP. Meanwhile, hydrogen ions are building up inside muscle cells, giving us that burn we love so much. Blood rushes into the capillaries surrounding muscle cells and fluid and nutrients (oxygen, etc.) diffuse from the capillaries into the muscle cell. On the other end, fluid minus the nutrients exits the muscle cell by diffusing back into capillaries. this is what the science community calls osmosis. When the hydrostatic pressure pushing fluid into the cell is greater than the osmotic pressure pushing fluid out of the cell, fluid builds up and a pump occurs. its like hooking a firehose up to a waterbed....theres gonna be alot of pressure, this pressure we is what we feel in a pump.
The mechanism pushing fluid into the cells and around them is much more effective than the mechanism pushing fluid out. Thats why after a while, you pump goes away...usually after an hour or so.
alot of people get "back pumps" especially in the low back because our back is a very active stabilizer muscle. when were doing any exercise (given we use proper form) our back should always be engaged. With the popularity of pre workouts thats contain large amounts of of vasodiolators (ie: agamatine) it allows much much MUCH more blood and fluid to flow into the cells...the problem...the muscle cells can only remove so much of the excess, used fluid at one time. so...the more fluid you have coming in equates to more fluid buildup in the space around the muscle cells (sarcoplasm) which gives us bigger better bumps...sometimes to the point of being paintfull.
This phenomenon is even more exacerbated when people combine anabolics into their nutrion and supplementation. this causes a much higher up take of nitrogen into the cells which allows for a much faster and greater volume of protein synthesis (which is a genetic process). This is why taurine could anecdotally reduce the felt effects of pumps because the cell uses this particular amino acid for a number of cellular processes, not just muscle protein synthesis. This could have the potential to cause the actual cell to retain more fluid which would slow the exit of the fluid out of the cell, which would lower the felt effects of your pumps.
hope this helps...i tried to keep it as simple, informative, and not too boring at the same time.
