All the studies looked only at thigh muscles — so we don’t know if the same results would apply to arms, shoulders, or calves.
Scientific Claim
All included studies in this meta-analysis assessed muscle fiber hypertrophy exclusively in the quadriceps femoris muscle, limiting generalizability to other muscle groups such as the upper body or soleus.
Original Statement
“It needs to be mentioned that the results presented in this meta-analysis are specific to the lower-body musculature. Specifically, all studies collected muscle biopsy samples from the quadriceps femoris muscle group...”
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 a factual description of the study selection criteria and methodology. No causal or generalizing language is used, and it aligns with the authors’ own caution.
Evidence from Studies
Supporting (1)
The Effects of Low-Load Vs. High-Load Resistance Training on Muscle Fiber Hypertrophy: A Meta-Analysis
The study looked at how different types of weight training affect muscle growth, but it didn’t say which muscles it studied — though most such studies use leg muscles like the quadriceps. Since it didn’t include upper body or calf muscles, the claim that it’s limited to one muscle group makes sense.