Increasing definition in your thighs requires developing muscle all over your body and decreasing your body fat percentage.
Training Techniques
Train your legs separately from any other muscle group. Include exercises that target each muscle in your lower body in each workout, including your quadriceps, hamstrings, glutes and calves.
Muscle Development
Begin your leg workouts with compound exercises that recruit multiple muscles at the same time to stimulate muscle development. Perform exercises such as the leg press, barbell squats and dumbbell lunges to work your quadriceps, hamstrings, glutes and calves at the same time.
Isolated Exercises
End your workouts with isolated exercises that target each muscle group individually, which helps correct any imbalances or asymmetry. Execute exercises such as leg extensions, lying hamstring curls, seated hamstring curls, standing calf raises and seated calf raises.
Cardio
Include 40 to 50 minutes of cardiovascular exercise after lifting weights when your glycogen levels are depleted, so your body is more likely to turn to stored fat as a fuel source. Ride the stationary bike at a fast pace with light resistance, pedal on the elliptical machine at a fast pace with light resistance or walk at an incline on the treadmill.
Engage in cardio workouts 5 to 6 days per week.
Health & Diet
Follow a healthy diet to help you shed body fat. Consume low-fat protein, such as fish, lean meats, skinless chicken, ground turkey, eggs, nuts and legumes, to help rebuild and repair your muscles. Eat complex carbohydrates, such as whole grains, vegetables and fruits to provide your body with a source of energy and improve your performance during workouts.