To add friends on Runtastic.com, go to a person’s Profile and click “Add as friend” right below his or her profile picture.
After refreshing, your pending friend request will be shown as “Pending friend request” below the profile picture of the person you friend-requested.
The user will receive an email notification (if they've enabled the “Notifications” settings) about the friend request from you.
Your friend request will appear on the right side on Runtastic.com where he or she can accept the request.
All your accepted friends are listed in the friends section, which you can find in the menu on the left-hand side.
Note: If you use the “Invite friends” feature, be aware that this is an invitation to join Runtastic.com, not a friend request. You need to send an actual friend request to people to add them as friends.