You can easily look up studies that date back to the 90's on some of them.. MK2866 and MK677 began having longer studies at that time... We have observed sarms use over a decade now and I have not come across long term use stories with issues whatsoever... clearly we have cycle lengths, dosing maxes etc. just like any other ped and/or supplement we have found to be safe and then max doses on things that you should not exceed... just like anything else, there is a lot of trial and error going on here as well...