Legs bruising from exercise?

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For the past week I have changed up my exercise routine. I have been doing P90x Plyometrics every two days, and two days off with some other exercise (like walking/running.) I've really been loving the plyometrics--I've never been so sore!

But my legs have bruises all over them now. Why is this? I'm not hitting myself when I exercise, I don't think.