Some people’s muscles grow a lot with training, others don’t—but if one person’s arms grow, their legs usually grow similarly, meaning your body’s natural response is more important than which muscles you train.

Scientific Claim

Interindividual variability in resistance training-induced muscle hypertrophy is greater between individuals than within individuals across upper and lower limbs, suggesting that biological factors unique to each person drive most of the variation in muscle growth.

Original Statement

“Despite considerable interindividual variability in hypertrophic responses, we observed that muscle hypertrophy following RET was relatively well conserved within versus between subjects...”

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

appropriately stated

Study Design Support

Design supports claim

Appropriate Language Strength

association

Can only show association/correlation

Assessment Explanation

The claim is based on within-subject comparisons and variability metrics reported in the abstract. The language 'conserved within versus between subjects' is descriptive and appropriately cautious.

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

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

Some people’s muscles grow a lot with training, others don’t—but if one person’s arms grow, their legs usually grow similarly, meaning your body’s natural response is more important than which muscle you train.

98%

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.

90%

Getting stronger from lifting weights doesn’t always mean your muscles are getting bigger—and vice versa. Strength and size don’t go hand in hand.

87%

Getting stronger from lifting weights doesn’t always mean your muscles are getting bigger—and vice versa. Strength and size don’t go hand in hand.

87%

Individual hypertrophic responsiveness to resistance training exhibits moderate inter-muscle correlation, but a substantial proportion of variability is attributable to non-exercise-specific biological factors.

83%