I quit full contact karate about 7-8 years ago (after doing it for a few years). I then went into soccer for the years after that, then i sat on my ass for a few years and this year i started hapkido. I realised that my back is really stiff (as well as alot of other body parts) comapred to how they were before. For example tensing and moving my shoulders down or up would make a lot of crackling noises (really gross and annoying). Are there any ways to stop this?