Some men gained more nuclei inside their fast-twitch muscle fibers when they drank protein and lifted up, while others gained them when they did the slow lowering motion—even without protein—showing that adding nuclei doesn’t always go hand-in-hand with muscle growth.
Scientific Claim
Myonuclei accretion in type II muscle fibers occurs only in response to either whey protein with concentric training or placebo with eccentric training, indicating that nuclear addition is not consistently linked to fiber growth and may be influenced by distinct mechanisms.
Original Statement
“In contrast, in the Whey group, an accretion of myonuclei in type II fibers was observed with Conc training (28 ± 9%, P < 0.01), while Ecc training did not influence myonuclei content... Additionally, in the Placebo group, an accretion of myonuclei was observed in type II fibers with Ecc training only (29 ± 8%, P < 0.01).”
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 accurately reflects the observed dissociation between myonuclear accretion and hypertrophy without implying causation. The data support an association between specific interventions and nuclear addition.
Evidence from Studies
Supporting (1)
Influence of exercise contraction mode and protein supplementation on human skeletal muscle satellite cell content and muscle fiber growth.
The study found that muscle cells add new nuclei in two weird ways: either with protein and lifting up (concentric), or with no protein and lowering down (eccentric)—but not in other combinations, showing it’s not just about getting bigger, but how you train and what you eat.