Do You Need a Pump to Build Muscle?
If you training with weights, then you'll probably be very familiar with the "pump" where your muscles get pumped full of blood making them look and feel bigger than they are. It's a great feeling and Arnold said that getting that "pump" is better than sex, sometimes.
The problem is that the pump will NOT build muscle as fast as high intensity training with 70% to 80% of your 1RM (repetition maximum). If we think about taking two 5kg and doing 100 reps of D/B flys, then you'll get a pump. Even if you did a second and third set, your reps might come down to only 50 reps but your pump will make your chest feel like it's twice the size.
If we then take a heavier weight that is around 70% to 80% 1RM and squeeze out 8 to 10 reps, you probably won't get that sort-after pump but your muscle will be forced to recruit ALL it's muscle fibers. This means that if you are getting the correct nutrition your body will incur more muscle damage from training 8 to 12 reps, resulting in more muscle and more strength than the 100 rep's of D/B flys.
It is important to note that the pump should be done by advanced bodybuilders who already have established the basic lean body muscle content that will enable them to get better rewards from doing the pump kind of training. The foundation of building up your lean body mass percentage is going to come from doing compound movements using 70% to 80% of your 1RM. That certainly does not mean that you will never get a pump again. It simply means that you are concentrating on intensity and reaching failure, or getting close to the point of failure. It goes without saying that when training with such a heavy weight that form or technique used is of paramount importance.
If you have been training for more than a year and you feel confident in your well-learned technique or form you use to execute the movements, then it's a good idea to cycle your pump workouts. That means that you do a week or two of only pump movements, doing 50 or 100 reps with a LOT less weight.
For more information checkout Muscle Shock Training Techniques.