Depends if you work with a rep or prefer a website. Helixx is well known but I have used three different websites and they all did what they were expected to. If I was ever going to take them again, which I won't, I would just buy from a reputable lab I trust.
Keep in mind Sarms are advertised as a 'safer' option but no one knows the long term side effects of most sarms. Ostarine is studied the most but it is still consider to be in its testing stage. None are sold to the public for sarcopenia that I know of.
AAS's - ones used with humans have a side effect profile, known issues, and known effects.
All that being said, if I was competing or wanted every possible edge, I would incorporate one at a time to hit every possible pathway for growth.
Keep in mind Sarms are advertised as a 'safer' option but no one knows the long term side effects of most sarms. Ostarine is studied the most but it is still consider to be in its testing stage. None are sold to the public for sarcopenia that I know of.
AAS's - ones used with humans have a side effect profile, known issues, and known effects.
All that being said, if I was competing or wanted every possible edge, I would incorporate one at a time to hit every possible pathway for growth.