As far as I know, that bug has been reported, but just in case you may wish to check bugtracker. Make sure you search it first. This bug has been around for at least the last 3 releases. It happens for me when I sit. If I don't WALK away from the spot where I sat down before hitting the run key my stamina rockets into the floor. No clue what causes it, but I bet they have some hotshot code-jockey working on it as we speak.