I was recommended to try Ashtanga yoga by a friend as its more dynamic and physical than hatha and iyengar. I was a bit reluctant to try out a class as I was afraid of being the only guy- stupid but thats how I felt!- but then someone mentioned doing one-on-one tuition. It is a bit more expensive but the individual attention and training make it worthwhile. I
I have done five classes so far and am really enjoying it. I can see how you would get fit doing ashtanga as it is difficult at first. You need to be relax and concentrate to achieve the poses.