When you perform any type of exercise involving your muscles, the demand increases your circulation – for two main reasons. First, in order to provide the extra energy and fuel needed to do the exercise. And second, to remove the build up of any waste products in the muscles. The increased circulation will almost
always result in a temporary increase in the size of the involved muscle groups – known as “pumping.”

In almost all types of normal daily work, the effects of pumping occur without being noticed. An example are the calves. Very few people are aware that their lower legs are usually at least half and inch larger at night than they are early in the morning. This is a direct result of pumping, as the calves increase their size during the normal course of the day. This is simply because of the degree of circulation needed in the calves throughout your day.

Pumping as it happens during a workout is no different. The only changed factors are the number of repetitions and the intensity of the exercise. The best thing about pumping is that it is a very clear sign that muscle growth has be stimulated. So, if no noticeable degree of pumping has be produced during your workout, then it is a sign that very little gains in muscle size and strength will be produced.

On the other hand, just because you produce extreme degrees of pumping, does not always indicate that you have stimulated increases in muscle size. It is quite easy to produce high degrees of pumping from certain exercises that will do very little to stimulate increases in muscle size and strength.

Fairly light movements performed in sets of very high repetitions, especially if they are performed in only “partial rep” style, will produce a very high degree of pumping, but will do very little to build muscle fast. Two or three sets, and in some cases only one set, of about ten to fifteen (and upwards of twenty for the lower body), will produce almost he same degree of muscular pumping, while also stimulating the maximum possible increases in muscle mass.