-Fluid/electrolyte intake: It is also very important that you keep your fluid and electrolyte(sodium,potassium,calcium,magnesium) intake very sufficient throughout the day. Fluid/electrolyte loss through training depletes interstitial fluids(basically the fluid that lies outside of the cells)which also attributes to muscle pump/cramping issues, and here's how:
Painful muscle pumps/cramps occur due to loss of the osmotically active particles(mainly NaCL or salt) outside the cell within the interstitial spaces. This causes a disturbance in the osmotic balance(pull) of fluid moving in and out of muscle cells. This then results in muscle cells excessively swelling(because they contain more osmotically active particles and fluid)and you develop very painful pumps. This process can also lead to problems with the calcium pump inside muscle cells. This will cause VERY painful cramps due to the muscle being locked in a contractive state. This is why adequate fluid and electrolye intake during training is very important to maintain this balance and prevent these issues.