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.
Scientific Claim
Resistance training-induced muscle hypertrophy is relatively conserved within individuals across upper and lower limbs and is unaffected by external load when training is performed to volitional fatigue, suggesting that individual biological factors play a larger role in hypertrophic response than load magnitude.
Original Statement
“we observed that muscle hypertrophy following RET was relatively well conserved within versus between subjects and was unaffected by load.”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design supports claim
Appropriate Language Strength
probability
Can suggest probability/likelihood
Assessment Explanation
The randomized within-subject design supports causal inference, but lack of blinding details and small sample reduce confidence. 'Unaffected by load' is a strong claim; 'suggests load may not be a primary driver' better reflects uncertainty.
More Accurate Statement
“Resistance training-induced muscle hypertrophy is relatively conserved within individuals across upper and lower limbs and may not be significantly influenced by external load when training is performed to volitional fatigue, suggesting individual biological factors play a larger role in hypertrophic response than load magnitude.”
Evidence from Studies
Supporting (1)
Resistance training load does not determine resistance training-induced hypertrophy across upper and lower limbs in healthy young males.
When people lift weights until they can't do any more, their muscles grow similarly in their arms and legs—no matter if they use heavy or light weights—because their body’s natural biology matters more than how heavy the weights are.