Really? I've seen lots of threads about fitness. Mostly about losing weight, but there are many about gaining muscle, as well. Actually, I just searched "fitness" and found these threads in the first two pages: http://www.lpsg.org/306429-abs.html http://www.lpsg.org/305441-fitness-question.html http://www.lpsg.org/303481-from-slim-to-muscle.html
It can take a bit of searching to get through the extraneous threads, but there's lots of variety on this site. Getting familiar with the search function is a good idea. :)
Also, not to be a grammar Nazi, but I find it really hard to read posts that have no periods in them.