A common misconception is you can perform certain leg exercises or rep ranges to increase your definition and visible muscle separation. This is simply not the case.
Weight training is an anaerobic activity no matter how you slice it and is not going to be a great fat burner or spot reduce fat in any one area. In other words, you can do leg extensions “until the cows come home” and you are not going to increase visible leg separation.
The primary function of weight training is to stimulate muscle growth. Every time you grab a weight you should keep this in mind. Muscle is best stimulated to grow by overload and that is why I train my legs as such, all year long.
Do you do any specific exercises for legs to bring out the muscle separation and definition?
I do not change my leg training or implement different exercises and rep schemes to increase definition. I always train with the basic free weight exercises like squats and perform them in a 4-8 repetition range. This is the best way to achieve maximum leg development.
Increasing muscle separation and definition is accomplished by lowering your body fat levels. To lower my body fat levels I progressively decrease my caloric intake and combine that with cardiovascular exercise. This combination creates the caloric deficit (fewer calories consumed than expended) needed to burn fat.
Don’t let yourself get confused, there are two parts to this equation. Weight training to increase muscular development and special attention to nutrition with cardiovascular exercise for increased muscle separation and definition.