Adrian Peterson says he wants HGH testing in NFL to show he is clean

It's hard, in this era of steroids, human growth hormone and whatever else athletes are using to enhance their performance, to not be skeptical of Adrian Peterson and what he did last season.
He suffered a bad knee injury late in the 2011 season, and less than a year later he rushed for more than 2,000 yards and almost broke Eric Dickerson's record. He looked even better than he did before his ACL surgery, and he has been pretty good ever since we took notice of him when he was at Oklahoma