Strength = muscle = mass. It's simply the way things are. Even with yoga which builds core strength and lean muscle and is known for not bulking people up... you still get slightly bigger simply because muscles are taking the shape they want to be in. More aggressive training will result in more aggressive results. I like my thighs. My thighs are ROCKS. They're no longer itty bitty, but they're strong and I'll gladly trade off itty bitty for strong any day.