She's actually just really fit. One of our first shoots together was a fitness comp. She has ripped abs like you would not believe. It's the same model in both pics which is why I posted them together. We traded time... she let me practice airbrushing on her (pic 1) and I updated her portfolio with some studio shots (pic 2).
#1 is a good shot; this sort of stuff isn't my taste, so I can't really offer anything else on it. In #2, I think you just missed your lighting. You've got a really hot area on the leading edge of her right arm, and shadow on the background. Nice work.