Even lifting light weights, as long as you push until you can't do another rep, can build muscle just as well as lifting heavy weights in people who already train regularly.
Scientific Claim
Low-load resistance training produces skeletal muscle hypertrophy similar to high-load resistance training in resistance-trained men when sets are taken to failure, suggesting training intensity alone is not the sole determinant of muscle growth.
Original Statement
“Each of the 4 studies showed that low-load RT elicited hypertrophic gains similar to high-load RT when sets were taken to failure.”
Evidence Quality Assessment
Claim Status
overstated
Study Design Support
Design cannot support claim
Appropriate Language Strength
association
Can only show association/correlation
Assessment Explanation
The abstract describes a systematic review of studies with unknown randomization, blinding, or control status; causation cannot be confirmed. The claim implies equivalence, but only association is supported by the evidence available.
More Accurate Statement
“Low-load resistance training is associated with skeletal muscle hypertrophy similar to that of high-load resistance training in resistance-trained men when sets are taken to failure.”
Evidence from Studies
Supporting (1)
The Effect of Low-Load Resistance Training on Skeletal Muscle Hypertrophy in Trained Men: A Critically Appraised Topic.
Even if you lift lighter weights, if you push your muscles until they’re exhausted, you can grow them just as much as if you lifted heavy weights—your muscles don’t care how heavy the weight is, just how hard you push them.