Putative benefits[edit]
Lean body mass[edit]
Studies have found that HGH reduces body fat[5][7] and increases lean body mass.[5] However, no increase in muscle strength was observed.[5][6] This may be explained by short-term fluid retention.[5]
Muscle mass[edit]
Researchers are still debating whether the more noticeable muscles are larger in size as well. It should be clarified, though, that muscle mass is not the same as muscle strength. Some say that human growth hormone will build muscle mass through raised insulin-like growth factors levels leading to heightened protein synthesis without any side effects[9] while other researchers argue that there have been no such findings on young healthy adults.[7] The second argument is more supported by research discoveries that HGH affects muscle protein synthesis no differently than a placebo does.[3]
Injury resistance[edit]
HGH may build up connective tissue within muscles, at least in the short term.[7] If these effects are real they “may promote resistance to injury or faster repair [but] would make the muscle no more capable of force generation”.[7] With the release of the Mitchell Report on December 13, 2007, 86 players were revealed to have used performance-enhancing drugs while playing in the Major Leagues. The report stated: "Players who use Human Growth Hormone apparently believe that it assists their ability to recover from injuries and fatigue".[10]