The Claim
In resistance-trained individuals aged approximately 21 years, performing 5 sets of 12 repetitions of leg press and leg extension exercises using cluster sets (3 clusters of 4 reps with 20-second rests) or traditional sets, over 8 weeks with twice-weekly training and effort matched to 0–1 repetitions in reserve, results in similar increases in rectus femoris muscle thickness (mean increase: 0.24 cm for cluster sets, 0.17 cm for traditional sets) and thigh lean tissue mass (mean increase: 171.8 g for cluster sets, 201.1 g for traditional sets), with no statistically significant difference between the two protocols.
What the research says
Supports is higher
Support is ahead, but a single strong opposing study can change this.
These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.
Among trained individuals around 21 years old, two different ways of performing leg exercises—cluster sets with short rests and traditional sets with no rests—produce nearly identical increases in muscle thickness and lean tissue mass in the thigh after 8 weeks of twice-weekly training.
See the scientific wording
In resistance-trained individuals aged 21 on average, performing 5 sets of 12 repetitions of leg press and leg extension exercises using either cluster sets (3 clusters of 4 reps with 20-second rests) or traditional sets, over 8 weeks with twice-weekly training and effort matched to 0–1 repetitions in reserve, results in similar increases in rectus femoris muscle thickness (mean increase: 0.24 cm for cluster sets, 0.17 cm for traditional sets) and thigh lean tissue mass (mean increase: 171.8 g for cluster sets, 201.1 g for traditional sets), with no statistically significant difference between protocols.
When muscles are worked close to failure, the force they generate stretches and damages muscle fibers, and the buildup of metabolic byproducts signals the muscle to build more protein, leading to growth — this happens the same way whether the workout has short breaks or not, as long as the total work and effort are identical.
What the research says
1 studyFor people who already lift weights, doing leg exercises with short breaks in the middle of a set (cluster sets) or without breaks (traditional sets) leads to almost the same muscle growth, as long as both are done just shy of failure.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.