The Claim
Differences in muscle hypertrophy between training protocols may fall within the range of typical measurement error and thus cannot be reliably distinguished.
What the research says
Roughly balanced
Support and challenge are close. The picture may shift as more studies come in.
These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.
The changes in muscle size caused by different workout routines may be too small to measure accurately with current tools, making it impossible to tell which routine is truly more effective.
See the scientific wording
Differences in muscle hypertrophy between training protocols may fall within the range of typical measurement error and thus cannot be reliably distinguished.
When muscles are worked under load, the tension on muscle fibers and the buildup of metabolic byproducts trigger signals that tell the muscle to build more protein and add new nuclei, leading to thicker muscle fibers. This happens whether the workout ends just before failure or at complete failure, as long as the total workload is similar. The muscle grows in size because the body adds more contractile material and supporting structures, and the measurement tools cannot reliably detect tiny differences in growth between similar training styles.
What the research says
3 studiesTwo different workout styles made muscles grow almost exactly the same amount — so close that the tools used to measure muscle growth couldn’t tell them apart. This means we can’t say for sure which workout is better just by looking at muscle size changes.
Study: Mixing Up Muscle Lengths: The Effects of Training at Different Muscle Lengths in the Elbow Flexors
This study found that two different ways of doing arm curls led to almost the same muscle growth, meaning the tiny differences between them might just be due to measurement mistakes, not real effects.
Study: The effect of myofibril and sarcoplasmic hypertrophy training on muscle hypertrophy and strength
This study found that two different types of weight training made muscles grow in noticeably different amounts, which means you can tell them apart — so the claim that they're too similar to measure is wrong.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 3 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.