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causal
Analysis v1
Supported

Lifting lighter weights many times until you can't do any more builds as much muscle as lifting heavy weights a few times in people who already exercise regularly.

53
Pro
39
Against

Evidence from Studies

Supporting (3)

53

Community contributions welcome

48

Resistance Training Load Effects on Muscle Hypertrophy and Strength Gain: Systematic Review and Network Meta-analysis

Systematic Review With Meta-Analysis
Human
2021 Jun 1

The study found that lifting lighter weights many times until you can't do more builds muscle just as well as lifting heavy weights a few times until failure, which matches the claim.

37

Comparable Strength and Hypertrophic Adaptations to Low-Load and High-Load Resistance Exercise Training in Trained Individuals: Many Roads Lead to Rome

Randomized Controlled Trial
Human

The study found that lifting lighter weights many times and lifting heavy weights a few times both made muscles grow about the same amount in people who already work out, which matches the claim.

25

Divergent Strength Gains but Similar Hypertrophy After Low-Load and High-Load Resistance Exercise Training in Trained Individuals: Many Roads Lead to Rome.

Randomized Controlled Trial
Human
2025 Sep 1

The study shows that lifting light weights many times until you can't lift anymore makes muscles grow just as much as lifting heavy weights a few times in people who already work out.

Contradicting (1)

39

Community contributions welcome

39

Measuring the Parameters of Maximum Muscle Strength, Muscle Mass, Muscle Damage in Active Adult Males after Low–Load High–Repetition with High–Load Low–Repetition Resistance Training

Cross-Sectional Study
Human

The study shows that lifting heavy weights for fewer reps builds more muscle than lifting lighter weights for more reps, which goes against the claim that both methods are similar for muscle growth.

Gold Standard Evidence Needed

According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.

Similar Assertions

When people who are already fit push themselves as hard as they can during weight training, it doesn't matter if they lift heavy weights for a few reps or lighter weights for many reps—both ways build muscle about the same.

53
0
97%

Lifting weights until you can't lift anymore makes muscles grow bigger no matter how heavy the weights are, but using heavier weights builds more strength than lighter ones.

48
41
89%

You can build muscle just as well lifting light weights as heavy ones — as long as you push yourself until you can’t do another rep.

59
0
88%

If you lift weights until you can’t do another rep, it doesn’t matter if you’re using light, medium, or heavy weights—you’ll still grow your muscles about the same, as long as you push yourself hard and do enough total work.

48
0
87%

Whether you lift light weights with lots of reps or heavy weights with few reps—so long as you push until you can’t do another rep—you’ll build muscle about the same amount.

48
0
87%

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