When training for some serious strength, power, and mass there is a multitude of ways to add variability to your resistance-training program. Typically variation is attained by manipulating volume, intensity, frequency, and exercise selection. However, rest can be manipulated, not just between sets but between reps as well.
Introducing the Cluster Set
A cluster set is breaking up a set with inter-rep rest, meaning each rep or grouping of reps can be broken up with brief rest before a longer period of recovery prior to the next set. For example a traditional set of 10 repetitions is done non-stop; however, a cluster set would be a grouping of 2 rep clusters followed by 5-15 seconds of rest between each cluster until 10 repetitions are completed. Not only can this add variability to your resistance-training program, it can allow more efficient muscular contractions by decreasing fatigue through the entire set. Inter-rep rest increases the recovery of phosphocreatine.
Some exercise scientists speculate that muscular failure during sustained contractions is brought about by phosphate being trapped during the myosin-actin cross bridge cycling, decreasing power stroke turnover rate. Inter-rep rest may alleviate this stress. A cluster set can be used with great variability as well. A cluster set can be manipulated in an ascending, descending wave, or standard cluster depending on the training phase. Here is an example of each cluster.
Standard Cluster: Manipulating inter-rep rest only, each set uses inter-rep rest between each rep or grouping of reps.
Ascending Cluster: Manipulating inter-rep rest and intensity in an increasing manner between reps or grouping of reps.
Descending Cluster: Manipulating inter-rep rest and decreasing intensity between reps.
Wave Cluster: Manipulate inter-rep rest and intensity (descend/ascend).
Either of these examples can be used to add variability to your resistance-training program. Utilizing a standard cluster works best for muscular strength and hypertrophy; standard cluster sets allow you to train at a higher intensity with more volume inducing more strength and mass gain. You can typically hit 5 reps with your 3-rep max for any strength exercise if you manipulate the inter rep rest. For example take your 3 rep max bench and between reps rest anywhere between 15-30 seconds to push your volume to 5 reps per set. This will allow you to train with a higher volume with a greater intensity.
Descending cluster sets are great for inducing some serious hypertrophy this will allow you to increase your volume while engaging more muscle fibers early in the set less rest is desirable with these sets. The ascending cluster sets is designed more for strength and speed/power development, which works an individual up to heavier weights later into a set. An individual will work at multiple velocities in an ascending manner increasing force later into a set with higher velocities in the early reps of a set.
A wave cluster set is great for developing that speed/power development this allows an individual to train at different velocities with exercises starting with a low force followed by a high force movements much liked the premise of super setting a strength exercise with a plyometric exercise however this can be used for a more specific task such as an Olympic lift or powerlifting movement, both working on speed and strength.
Sample Cluster Set Workouts
Next are some sample workouts that anyone can use depending on their program goals.