http://AskTheTrainer.com/lunge-exercise.html Certified Strength and Conditioning Specialist Mike Behnken, MS, CSCS The lunge exercise and Pushback Lunges are great for your legs and glutes. You can perform them explosively pushing yourself back to the original position from your heel. Proper lunge form should have your front knee at around a 90 degree angle with the middle of your knee above your heel. This will allow proper hamstring and glute activation while you work your quads. For resistance you can use Kettlebells or dumbbells or sacks of potatoes it doesn't matter as long as you keep your torso upright and do not bend your back. Remember if you have excess fat covering your muscles you will not tone up. Certified Personal Trainer Michael Behnken, MS, NASM-CPT http://AskTheTrainer.com/average-percent-body-fat.html