I have used somatomedin-LR before. I did put on significant muscle during that 30 day period. Theoretically, IGF is superior to HGH for muscle building simply based on the fact that the anabolic effects of somatotropin are due to its causing the release of somatomedin. Thus, it makes more sense to use the downstream component that's directly responsible for muscle building. But I prefer IGF-1 DES to IGF-LR3 any day. 30 minute half-life with 10 times the potency makes it a no-brainer. I posit that only pEG-MGF beats IGF-1 DES in the muscle-building arena, until Tren remains retired of course.