We check this website, now mapmyfitness.com is up and dont blocked for our system and other users of the Internet.
So, answer to question: Is mapmyfitness Down Right Now? - NO! mapmyfitness is up!
If you have problem with access to site mapmyfitness, and domain mapmyfitness.com is not avalible.
Clear browser cache and/or try other web browser
(Chrome, Firefox or Safari).