Whether someone has more slow-twitch or fast-twitch muscle fibers doesn't predict how much bigger or stronger their muscles will get after 10 weeks of lifting weights to exhaustion, even though people's results vary a lot.
Scientific Claim
Muscle typology, as estimated by muscle carnosine levels, does not explain the high inter-individual variability in muscle hypertrophy or strength gains following 10 weeks of resistance training to failure at 60% 1RM in untrained individuals, despite observed ranges of +3% to +14% in muscle volume and +17% to +47% in strength.
Original Statement
“The training response for total muscle volume (+3 to +14%), fibre size (−19 to +22%) and strength (+17 to +47%) showed considerable inter-individual variability, but these could not be attributed to differences in muscle typology.”
Evidence Quality Assessment
Claim Status
overstated
Study Design Support
Design supports claim
Appropriate Language Strength
probability
Can suggest probability/likelihood
Assessment Explanation
The study concludes 'cannot explain' — an absolute claim — but the small sample size (n=21) and lack of power to detect small effects mean it only shows no evidence of explanation, not proof of absence.
More Accurate Statement
“Muscle typology, as estimated by muscle carnosine levels, did not explain the high inter-individual variability in muscle hypertrophy or strength gains following 10 weeks of resistance training to failure at 60% 1RM in untrained individuals, though it may still play a role not detected due to limited statistical power.”
Evidence from Studies
Supporting (1)
Can muscle typology explain the inter‐individual variability in resistance training adaptations?
Even though some people gained more muscle and strength than others after the same workout routine, it wasn’t because they had more fast- or slow-twitch muscle fibers—those differences didn’t explain why some people improved more than others.