It is important to understand that high reps with light weights does not equal more definition. Increasing your definition is the result of reducing your body fat and that is accomplished by paying close attention to your diet and incorporating cardiovascular exercise. Training with higher reps and lighter weights will not burn fat but it will reduce the stimulus for muscle growth.
The weight training component of your exercise plan should be designed to build muscle and the most effective and efficient way to do that is with the Max-OT principles. If you are using the Max-OT principles you’ll be creating the best stimulus for strength and development by progressively overloading the muscles in a 4-6 rep range.
To lose body fat and increase your definition you need to keep a close eye on your daily caloric intake and work Max-OT Cardio into your training schedule.
A combination of Max-OT training to build muscle and attention to your diet along with Max-OT Cardio to burn fat is the best way to achieve greater definition.