The Lunge Pulse is a sure way to fire up your quads. Apply the basic principals of a lunge to start this movement: One knee is bent at ninety degrees in front of your body and the other is bent at ninety degrees underneath you, knee resting directly under the head. From this position, you simply lift the knee on the ground to about 6-12" off the ground and return it to the ground over and over for any given duration of time. You perform one leg entirely, and then the other.
A single leg squat.
1. Sit your hips back behind your heel.
2. Positioning your suspended leg and arms out in front of your body to balance.
*This move can also be done on an elevated platform at a more shallow squat.