Sore Ankles! Too Fat or wrong Technique?

Hey people! I'm currently into day 14 of Jillian Michaels 30 Day Shred Video. I am 5'4" and weigh 204 lbs. This past weekend while playing softball as I went to sprint to first base I notice my ankles felt very sore. I felt like they couldn't hold me up. I was wondering if I am doing something wrong during the video or if I am too fat still to be doing this kind of activities? Any suggestions? It feels tight in the back of my ankles. Thanks!