The lateral lunge is a variation of the standard lunge that works the quadriceps and hamstring muscles by lunging to the side rather than forward. The document provides instructions for proper form, including keeping the leading knee bent at a 90 degree angle, the back straight, and the trailing leg straight. Improper form can lead to injury and rounding of the back. The lateral lunge targets the quadriceps, hamstrings, glutes, and ankle muscles and can be used for strength and endurance training when performed with or without additional weight.