Is there a limit to the number of challenges you can be in at once?
New users who have not completed a challenge from start to finish are limited to joining five active challenges at once. After successfully completing at least one Spar challenge, you will be able to join more than five active challenges at once.
From our experience, we found it's common for new users to join more challenges than they can handle. If you have never completed a Spar challenge, it's difficult to understand what you're getting yourself into.