Whether you lift heavy weights for fewer reps or light weights for more reps—as long as you push until you can’t do another rep—your muscles grow about the same amount.

Scientific Claim

Resistance training-induced muscle hypertrophy is similar between higher-load (70–80% 1RM, 8–12 reps) and lower-load (30–40% 1RM, 20–25 reps) protocols when performed to volitional fatigue in healthy young males, indicating that external load does not determine hypertrophic outcomes under these conditions.

Original Statement

“we observed that muscle hypertrophy following RET was relatively well conserved within versus between subjects and was unaffected by load.”

From study:Resistance training load does not determine resistance training-induced hypertrophy across upper and lower limbs in healthy young males.

Evidence Quality Assessment

Claim Status

overstated

Study Design Support

Design supports claim

Appropriate Language Strength

association

Can only show association/correlation

Assessment Explanation

Although randomization supports causal inference, blinding and measurement bias are unknown. The abstract uses 'unaffected by load'—a definitive causal claim—but without full methodological verification, 'associated with' is more conservative.

More Accurate Statement

“Resistance training-induced muscle hypertrophy is associated with similar outcomes between higher-load (70–80% 1RM, 8–12 reps) and lower-load (30–40% 1RM, 20–25 reps) protocols when performed to volitional fatigue in healthy young males.”

Evidence from Studies

Supporting (1)

Resistance training load does not determine resistance training-induced hypertrophy across upper and lower limbs in healthy young males.

Randomized Controlled Trial

Human

2025 Dec 31

When people lift weights to the point of exhaustion, whether they use heavy or light weights, their muscles grow about the same — it’s how hard they try, not how heavy the weights are, that matters.

Contradicting (0)

No contradicting evidence found

Source Study

Resistance training load does not determine resistance training-induced hypertrophy across upper and lower limbs in healthy young males.

Score: 46

DOI: 10.1113/JP289684

Similar Assertions

Whether you lift heavy weights with fewer reps or light weights with more reps—as long as you push until you can’t do another rep—your muscles grow about the same amount.

98%

When people lift weights until they can't do another rep, their muscles grow about the same amount whether they use heavy or light weights — and how much they grow depends more on their own body than on how heavy the weights are.

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When you train hard enough to fail on every set, how heavy the weights are matters less than your body’s natural ability to grow muscle.

90%

If you train hard enough to fail on every set, how heavy the weights are matters less than your body’s natural ability to grow muscle.

90%

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.

86%