i agree.
when you work out, instead of doing 6 - 10 reps on your legs, switch to a high-rep workout for them by choosing a very
light weight that will allow you to complete 15, 20, or even 25 reps. like monkey said, you just need to look at the difference between sprinters (BIG thighs, BIG muscles in the butt from short but explosive movements) and
marathon runners (long, skinny, stringy muscles from going and going and going and going and...).
um.. not to be rude, but you're sure it's muscle causing the size problem? you might have a fat buildup on your thighs like most of us women do and those can be a REAL female canine to shift because that part of the body contains the lowest levels of... dammit, forgot the name, but it's a body chemical (hormone, the like) used to trigger local fat burning.