Front squats are a great exercise for the front of the legs. be sure you keep very strict form to get the best results.
Starting position – Use a squat rack to support the weight between sets. Place a barbell across your chest and shoulders. Bring your arms up under the bar and cross them over it and use your hands to hold the bar and support it. Place your feet a little wider than shoulder width apart with your toes pointed slightly outward.
Movement – Keep your back straight and flexed with your head up. Bend at your knees and keep the weight centered over your feet and knees. Lower the weight until you are at a 90 degree angle then straighten back up concentrating on using your legs to push the weight up.