The pump is the short-term sensation you experience during training when your muscles fill up with blood faster than the blood can leave the area, making the muscles appear fuller and larger. It’s a tight, swelled feeling, often accompanied by an increase in vascularity. Pump workouts generally involve medium (8-12) or higher (13-20+) repetitions, supersets/trisets/giant sets, and/or brief rest intervals between sets.
You’ll hear some strength coaches and functional training experts knock pumping workouts because they claim pumping is cosmetic only and emphasizes “form over function.” That may be true, however, if you’re interested in bodybuilding or physique development, then maximum pump can be very beneficial.
Most bodybuilders and even most exercise physiologists would agree that workouts that produce maximum pump can provide up to 20-25% of the increase in muscle size. This comes from sarcoplasmic and mitochondrial hypertrophy and increased capillarization. However, the pump has virtually nothing to do with increased myofibrillar hypertrophy – the actual fiber growth that’s responsible for 75-80% of the increase in muscle size. That type of fiber growth comes only from heavy training, which produces little, if any pump. Sarcoplasmic hypertrophy looks good and is beneficial to bodybuilders, but you do tend to lose it more quickly with de-training.
For me a “good pump” can be a good indicator of an effective workout from a bodybuilding standpoint.
As important the pump might be for bodybuilders, the criteria that’s MUCH, MUCH more important than pump is PROGRESSIVE OVERLOAD. Nothing is more important in bodybuilding or strength training than progressive overload. This means you must beat your previous workouts and increase the amount of weight you use in a slow, steady and systematic fashion.
Remember something, you can get a pump by dropping down on the floor and doing a few sets of push ups, but that doesn’t mean you are going to get permanent gains in muscle size.