The ‘mus­cle pump’ is described as when you put your mus­cles under an extended period of con­stant ten­sion. As your mus­cles stretch and con­tract they become gorged with blood that makes them feel tighter and fuller.

Get­ting a mus­cle pump is not nec­es­sar­ily what causes the mus­cle to grow. Doing 100 reps with a light weight will cre­ate a huge pump – but does this make a mus­cle grow? Of course not! Dis­tance run­ners get a pump in their legs when they sprint uphill and do they get big mus­cles? Heck, no!

Most body­builders swear by the ‘pump’ and preach that you are shut­tling more nutri­ents into the mus­cle – but is that what is really hap­pen­ing? Sure it feels great, like Arnold says in the unfor­get­table scene in Pump­ing Iron, but all that is occur­ring is a ‘back-up’ of blood. The blood is ‘stuck’ inside the mus­cle, which cre­ates that much wor­shiped tight and full look.

The blood that’s backed up into the mus­cle has hit a dead end and has nowhere to go. If you had fresh, new blood, that would be great, but unfor­tu­nately you just have old, stale blood get­ting ready for a snooze. That will NOT help you gain weight or build mus­cle mass! The pump that is built up by the blood in your mus­cles will usu­ally occur after you repeat set after set, which results in the famous ‘burn­ing’ sen­sa­tion known as lac­tic acid. Lac­tic acid forms in the absence of oxy­gen. Lac­tic acid is a WASTE prod­uct and does NOTHING to build mus­cle weight.

Now if you are lift­ing extremely heavy weights and achiev­ing a pump, then this is a very good indi­ca­tion that you are mak­ing the mus­cle fibers work fully. I would only use the pump as an indi­ca­tor to reveal how well you are ‘tar­get­ing’ the work­ing mus­cle, not as a guide to mark your success.

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