kilojoules burned from martial arts

Hi folks - did the kilojoules burnt count suddenly change for "Judo, karate, kick boxing, tae kwan do"? I used MFP regularly until I went travelling last year, & have recently re-started. I was very disappointed to find that no matter what I did, my karate kJs were not offsetting my food much at all, and then presto! today it did. There seems to be a bug: on the exercise database it reads that 55 mins should equate for me to 2589 burned, but then when I log it, I'm getting a paltry 819.