People grow muscle at very different rates — but each person tends to grow their arms and legs similarly, no matter what weight they use. This means your genes and biology matter more than how heavy your weights are.
Scientific Claim
Variation in resistance training-induced muscle hypertrophy occurs independently of external load and is more consistent within individuals than between individuals, indicating that personal biological factors are the primary source of differences in muscle growth.
Original Statement
“Variation in RET-induced muscle hypertrophy occurred independent of external load and was relatively well conserved (i.e., retention of the hypertrophic response) across different anatomical limbs within an individual.”
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 small sample and lack of blinding reduce confidence. 'Occurs independent of' is strong; 'suggests independence' is more cautious and appropriate.
More Accurate Statement
“Variation in resistance training-induced muscle hypertrophy is likely independent of external load and is more consistent within individuals than between individuals, suggesting that personal biological factors are the primary source of differences in muscle growth.”
Evidence from Studies
Supporting (1)
Resistance training load does not determine resistance training-induced hypertrophy across upper and lower limbs in healthy young males.
Even when people lifted heavy or light weights, their muscles grew similarly within their own body—some people’s muscles grew a lot, others hardly at all, but each person’s pattern stayed the same across arms and legs, suggesting your genes and biology matter more than how heavy the weights are.