After doing heavy leg workouts, the muscles of trained men show a big spike in two specific proteins (IGF-IEa and MGF) that help repair muscle damage, and this spike happens about two days later.
Scientific Claim
Heavy resistance exercise involving 5 × 10RM leg presses and 4 × 10RM squats is associated with a 1.7-fold increase in IGF-IEa mRNA expression and a 3.1-fold increase in MGF mRNA expression in the vastus lateralis muscle of strength-trained men 48 hours post-exercise, suggesting these isoforms may play a role in muscle repair processes following mechanical stress.
Original Statement
“When compared to the corresponding pre-exercise value, a significant increase (a fold change of 1.7 ± 0.3 from the pre-exercise value, p < 0.05) occurred in IGF-IEa mRNA expression at 48 hours postexercise. The MGF mRNA expression also increased (a fold change of 3.1 ±1.8, p < 0.05) compared to pre-exercise values.”
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 study design is observational with no control group or randomization, so causal language is inappropriate. The claim correctly uses 'associated with' and reports measured fold-changes and p-values, aligning with the evidence level.
Evidence from Studies
Supporting (1)
This study found that after doing heavy leg workouts, the muscles made more of two special proteins (IGF-IEa and MGF) that help repair damage — exactly what the claim says.