Even when accounting for differences in weight, fitness, and blood sugar, the more IGF-I went up, the better the muscle energy recovery — meaning IGF-I likely has a direct role.
Scientific Claim
In obese adults with reduced GH, increases in IGF-I were significantly associated with improved phosphocreatine recovery even after adjusting for age, sex, race, body fat, lean mass, and insulin sensitivity, suggesting the relationship is independent of these confounders.
Original Statement
“This association remained significant after controlling for age, sex, race, ethnicity, and parameters of body composition and insulin sensitivity (all P<.05).”
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 use of multivariate modeling supports a robust association, but the small sample size and lack of between-group significance prevent causal claims. 'Associated' is the correct verb strength.
Evidence from Studies
Supporting (1)
The effects of tesamorelin on phosphocreatine recovery in obese subjects with reduced GH.
This study found that when obese people with low growth hormone got a treatment that raised IGF-I levels, their muscles recovered energy faster after exercise — and this happened even after accounting for things like age, weight, and insulin levels, meaning IGF-I itself was likely the key factor.