With cluster training, a lifter can break up work sets with short rest periods to perform more reps than normal.
For example: Instead of doing one set of eight reps and then resting two minutes before attempting your next set, you'd use a cluster (hence the name) of three smaller, shorter sets of three reps, each interspersed with a 30-second break. The end result? More reps at a higher weight—and that means progress.
Here's how to apply it to your regular chest workout:
1) Choose a compound barbell exercise that works the chest, such as a bench press, incline press, or decline press. Choose a load that allows you five reps, but perform only two.
2) Rest 10 seconds and repeat for three more mini sets. Now rest two minutes. That’s one cluster.
3) Repeat the whole process for five total clusters. You will have done 40 total reps. Compare that with a typical prescription of three sets of five reps (for 15 total reps), and you can see how much more powerful cluster training can be without pushing you to your limit.