The Claim

Interindividual variability in muscle hypertrophy following resistance training is substantially greater between individuals than within individuals across upper and lower limbs, indicating that inherent biological factors are the dominant source of variation in muscle growth responses.

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

What the research says

Supports is higher

Support is ahead, but a single strong opposing study can change this.

Supports
66score
Challenges
0score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

How it works
1 study reviewed
In plain English

People respond differently to resistance training in terms of muscle growth, and these differences between individuals are much larger than the differences in muscle growth within the same person across different body parts, meaning biological differences between people are the main reason for varying results.

See the scientific wording

Interindividual variability in resistance training-induced muscle hypertrophy is substantially greater between individuals than within individuals across upper and lower limbs, suggesting inherent biological factors are the dominant source of variation in muscle growth responses.

Why this might work

Each person's muscles have a fixed biological setting that controls how much new muscle protein they build after lifting weights. This setting determines how strongly their muscle fibers respond to tension, and it stays the same across all limbs, so arms and legs grow at the same relative rate in each person, even if they train them differently.

Verified mechanismbased on 1 study

What the research says

1 study

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

    People grow muscle at different rates when they lift weights, but the same person tends to grow muscle similarly in their arms and legs—even if they use different weights. This suggests your genes and body biology, not the workout itself, are what really determine how much muscle you gain.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies

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