By adjusting the weight based on how close you are to failure (RIR), both types of sets end up using about the same weight—even though cluster sets seem like they should let you lift heavier.
Scientific Claim
The use of repetitions in reserve (RIR) to individualize load in cluster and traditional sets results in comparable training intensities (%1-RM) across protocols, preventing cluster sets from accumulating higher volume loads despite their structural advantages.
Original Statement
“The loads for each protocol were adjusted to reach failure or be within a maximum of one repetition from failure (i.e., repetitions in reserve [RIR] of 0–1). [...] no statistically significant differences were found between conditions in any session for either the leg extension or leg press exercises.”
Evidence Quality Assessment
Claim Status
overstated
Study Design Support
Design supports claim
Appropriate Language Strength
association
Can only show association/correlation
Assessment Explanation
The claim implies a causal mechanism ('results in'), but the study design cannot confirm causation. Only an association between RIR matching and equalized intensity can be supported.
More Accurate Statement
“In resistance-trained individuals, using repetitions in reserve (RIR) to individualize load in cluster and traditional sets is associated with comparable training intensities (%1-RM) across protocols, preventing cluster sets from accumulating higher volume loads despite their structural advantages.”
Evidence from Studies
Supporting (1)
Cluster sets and traditional sets elicit similar muscular hypertrophy: a volume and effort-matched study in resistance-trained individuals
When both types of workouts were done with the same effort level (using RIR to adjust weights), neither one built more muscle than the other—even though cluster sets have breaks in between reps. So, the breaks didn’t let people lift heavier or do more work overall.