When people who already lift weights do either short breaks between reps (cluster sets) or long continuous sets (traditional sets), both ways make their muscles grow about the same amount if they work just as hard and do the same total number of reps.

Scientific Claim

In resistance-trained individuals, cluster sets and traditional sets, when matched for total repetitions, sets, and effort level (0–1 RIR), produce similar increases in rectus femoris muscle thickness (effect size: 0.56 vs. 0.42) and thigh lean tissue mass (effect size: 0.11 vs. 0.13) over an 8-week training period, suggesting that set configuration does not differentially influence hypertrophic outcomes under these conditions.

Original Statement

“Results showed similar increases in muscle thickness (p < 0.001, ES = 0.56, and p = 0.012, ES = 0.42, respectively) and lean tissue mass (p = 0.002, ES = 0.11, and p < 0.001, ES = 0.13, respectively) in both CS and TS conditions.”

From study:Cluster sets and traditional sets elicit similar muscular hypertrophy: a volume and effort-matched study in resistance-trained individuals

Evidence Quality Assessment

Claim Status

overstated

Study Design Support

Design supports claim

Appropriate Language Strength

association

Can only show association/correlation

Assessment Explanation

The study uses a within-subject design but lacks confirmed randomization, so causal language like 'produce similar increases' overstates the evidence. Only association can be claimed.

More Accurate Statement

“In resistance-trained individuals, cluster sets and traditional sets, when matched for total repetitions, sets, and effort level (0–1 RIR), are associated with similar increases in rectus femoris muscle thickness (effect size: 0.56 vs. 0.42) and thigh lean tissue mass (effect size: 0.11 vs. 0.13) over an 8-week training period, suggesting that set configuration does not differentially influence hypertrophic outcomes under these conditions.”

Evidence from Studies

Supporting (1)

Cluster sets and traditional sets elicit similar muscular hypertrophy: a volume and effort-matched study in resistance-trained individuals

Randomized Controlled Trial

Human

2025 Jun

This study found that whether you take short breaks between small groups of lifts (cluster sets) or do all your lifts in one go (traditional sets), you get the same muscle growth as long as you do the same total number of lifts and push yourself just as hard.

Contradicting (0)

No contradicting evidence found

Source Study

Cluster sets and traditional sets elicit similar muscular hypertrophy: a volume and effort-matched study in resistance-trained individuals

Score: 45

DOI: 10.1007/s00421-025-05712-6

Similar Assertions

If you’re already experienced with weightlifting, doing either kind of set—short breaks or long continuous sets—will make your muscles grow, as long as you’re working hard and doing the same total amount of work.

81%

If you’re already experienced with weightlifting and train your legs twice a week for 8 weeks with hard sets, your muscles will grow whether you take short breaks between reps or not.

78%

Not all weightlifting exercises are equal — exercises that work multiple muscles at once (like squats) should count as half a set when predicting muscle growth, because they help but aren’t the main target.

75%

This study only looked at the front and side of the thigh—so we don’t know if doing more sets helps your front thigh or hamstrings grow more.

73%

For guys who already lift weights, doing 5 to 10 sets per muscle group each week builds strength and muscle just as well as doing 15 to 20 sets — more sets don’t help much.

72%