Legs seem like the hardest bodypart to use intensity techniques on. Besides the leg extension what can I do to push my legs to new growth?
Legs are enough of a killer without making your workout harder. Partials are a great technique to use with legs. You can do partial reps on the leg press or with squats in the Smith machine or squat rack. Another good exercise would be partial lunges. Pick a heavier weight than you would normally use, and descend only halfway through each rep.