not too bad man. I think they are a little dark and perhaps a bit too much motion blur. I think stopping down a little less and upping the ISO would have helped. I'd also suggest really watching your backgrounds. In this case, the sky looked pretty tough but just a little more to the left of the frame are some nice dark woods...These things aren't always second nature (and often can't be controlled) but they can make a huge difference in athlete isolation as well as impact your metering and exposure depending on which mode you are using.
But honestly, what I would add is make sure you know which athlete you want to be sharp. Then, try to set them up on your selected focus point (or manually focus on them) and track that one person throughout.
