When you exercise a certain muscle group there is a huge rush of blood that goes to that area and you experience a 'pump' within the muscle. Most of you will be familiar with this. But did you know you can maximise your sets by possibly an extra 10-15% by performing isometric contractions between sets during your rest periods.
What does this mean? Well, take for instance the chest muscles. Once you perform your set of chest press you will increase circulatory blood flow to that area. When the set is complete you will rest but during this time keep the chest muscles contracted for approximately 20-30 seconds. This will help promote blood flow, oxygen uptake within the muscles and will give you a bigger muscular pump. You may even find you are stronger during your next set of the same exercise. This principle can be applied to all the other muscle groups too.
Give this a try to maximise your sessions and endure the burn!!