I learned this method from a former workmate and training partner 20 years ago. We used it mainly as a finisher for the arms.
It’s very simple. Pick a movement and split it in two parts. Ideally two halfs, or at a particular sticking point. Begin with the weakest part of the movement and do 7 reps (first half). Without pause continue with the other part of the movement (second half) and do 7 reps. When done finish of with 7 reps of the full movement.
It creates a marvelous pump and burn if you do it right. The idea with the pump is to stimulate increase in blood flow to a particular muscle, which in turn bring nutrients and hormones needed for muscle growth.
Works very well for the arms, using variations of curls and tricep extensions. Feel free to try other movements, but be careful with complex exercises where fatigue could compromise technique. Use a spotter if necessary.
Watch video for a demonstration on dumbbell curls.