Getting the most out of every rep is key to making gains in size and strength, and this is exactly why cluster sets are worth trying for anyone with lofty gym goals. Quick refresher: Clusters involve taking at least one brief rest period during a lifting set, as opposed to a traditional straight set where all reps are performed consecutively with no break.
In a study recently published in The Journal of Strength and Conditioning Research, researchers from Texas Christian University and George Mason University compared cluster sets to traditional sets on barbell back squats. Every common training variable was kept the same: weight used (70 percent of one-rep max), number of sets (four), number of reps per set (10), even total rest time (two minutes per set). The only difference between the cluster- and traditional-set protocols was how the rest was dispersed.
With the clusters, each set consisted of doing five reps, resting 30 seconds, doing five more reps, then resting 90 seconds before repeating. Each traditional set involved simply doing 10 reps, then resting two minutes. (Total rest time in both cases is the same.)
Even with all the common variables, researchers found that greater power output and higher velocities were produced during cluster sets, particularly later in the sets (closer to 10 reps). This makes perfect sense when you consider that when doing clusters, reps six to 10 of each set are performed after 30 seconds of rest. It’s sort of like taking a halftime break (or more accurately, getting a 30-second timeout) during a tough set of squats. But hey, if that makes your last five reps of each set that much stronger, it’s worth trying during your next lifting session.