Originally Posted by $5 submissions

Forums
Bodybuilder directories
Submit bodybuilder articles to article submission sites
Post comments on bodybuilder blogs (build credibility with your 'expertise" then ask to be a featured "guest" blogger for them--with linkbacks to you, of course)
Build a bodybuilder blog
Start a social networking site page on bodybuilding
Join bodybuilding groups online

There's tons of other ways... mainstream is infinite