Periodization is a common way to focus on specific training adaptations. For example, a traditional periodization scheme would have a high- repetition strength-endurance phase, followed by a moderate-intensity, high-volume hypertrophy phase, and finishing with a high-intensity, low-volume strength or power phase. Because of the adaptive specificity of such training phases, it is thought that some desired adaptations such as power may be lost during the fatiguing high-volume hypertrophy phase. Cluster sets are a method of performing sets with a brief rest period in the middle of the set, resulting in multiple shorter sets, or “cluster” sets. What if cluster sets could prevent the decline in rep velocity and allow the lifter to maintain power while also building muscle?


Researchers from the Czech Republic, Australia, and the U.S. recently collaborated to see whether subjects could actually lift heavier weights using cluster sets while still maintaining time under tension (for hypertrophy), peak power, and work output. They had 12 strength-trained men perform three sets of 12 squats, using three different set structures: traditional sets with 60% 1RM (TS), cluster sets of four reps with 75% 1RM (CS4), and cluster sets of two reps with 80% 1RM (CS2).


The cluster-set approach allowed heavier weight to be lifted than traditional sets while resulting in similar declines in rep velocity. Additionally, using heavier weight led to slower rep velocity but resulted in greater total work and time under tension.


Cluster sets can be used to lift heavier weight for a given number of reps, resulting in greater workout output without sacrificing power or time under tension.


Break any set of 12 into groups of four reps with 30 seconds of unloaded rest in between. You would also still take the usual rest between sets. So for our example, do three clusters of four reps with 30 seconds of rest, then after the 12th rep, stop and take your usual two- or three-minute rest before doing it all again.