In people who took the placebo, IGF-I didn’t go up much, and their muscle energy recovery didn’t link to IGF-I — meaning the connection only showed up when the drug raised IGF-I.

In people who took tesamorelin, the more their IGF-I levels went up, the better their muscles recovered after exercise — and this link was even stronger than in the whole group.

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.

Even when researchers removed blurry or low-quality scans, the link between IGF-I and muscle energy recovery stayed strong — so the finding is reliable.

Even though the drug raised IGF-I levels, it didn’t make the muscle energy recovery noticeably better than the placebo — so the effect might be subtle or only show up in certain people.

In obese people with low growth hormone taking tesamorelin, the link between higher IGF-I and better muscle energy recovery is even stronger than in the whole study group.