Though this forum (and most like it) are much more focused on bodybuilding than sports, I'd like to gather some thoughts on this.
Here's an interesting paper that demonstrated a significant performance-enhancing effect for HGH usage, along with evidence of a synergistic relationship with exogenous testosterone use:
(I can't post links yet: Google "The Effects of Growth Hormone on Body Composition and Physical Performance in Recreational Athletes")
GH usage at 2mg/day increased anaerobic work capacity, which the researchers speculate could translate to a monster 0.4 improvement in a 100 meter sprint. When co-administered with 250mg/week of testosterone, this improvement in work capacity nearly doubled.
This has major implications for athletes who need sprint speed in their respective sports. My question is this: Most of us can't get real GH but can easily obtain peptides - does this dosage of GH translate in any comprehensible way to some dosage of a GHRH/GHRP or IGF-1? Could one realistically see the sort of improvements obtained in the study without the authentic GH?
I note the rather modest mean improvement in total testosterone with the 250mg/week cycle.