bro i have never once heard of 677 causing a sore neck... if i had heard that, even once, i would tell you there was some sort of correlation... i have NEVER heard of that whatsoever... now, hgh itself can cause discomfort with muscle or joint pain and stiffness in the hands and feet but that's hgh.. mk677 is a secretagogue, which will cause a release of hgh but it is not the same thing on the surface... i have seen some people have muscle soreness for a little over a week up around 2 weeks at the most but that's is not something i have seen often... perhaps your soreness is in your neck for whatever reason.. i have never heard that specific complaint... its just a general adjustment period to something new in your body and these sides are alleviated..