Explosive Quadricep Power!
The major muscles of the upper leg include the gluteus maximus, the sartorius, the quadriceps, and the hamstring muscles.
The quadriceps is composed of four muscles that cover the front of the thigh. Their major function is straightening the leg at the knee.
The four muscles of the quadriceps femoris muscle group are the vastus lateralis, vastus medialis, vastus intermedius and the rectus femoris.
The tendons of these four muscles merge together and attach onto the patella (kneecap) and surrounding ligaments.
The knee joint and the the muscles of the upper leg are used in kicking, skipping, jumping, running, lifting and pushing. The movement is one of the most important actions needed by most athletes, strength and power in these muscles are vitally important.
Kinesiology & Physiology
Common sense says that you don't knock out 20 sets for your triceps and only four sets for your biceps, and expect that you'll develop admirable arms. Likewise, it doesn't make sense to blast your thighs with 10 different exercises and work your hamstrings with only one, and maybe ignore your calves altogether. Instead, stress your muscles equally; symmetry of training produces symmetry of physique.
If you want good-looking legs that perform at their best, your leg workouts should involve these four elements: 1) balanced training, 2) sufficient recovery time, 3) isolation of key muscles and 4) ample variation.
The squat is generally considered to be the single best mass-building exercise. It strongly stresses the quadriceps, buttocks and lower back muscles.
Secondary emphasis is placed on the abdominal, upper back and hamstring muscle groups. Consistent heavy squatting will make your body's metabolism more conducive to adding muscle mass all over your physique, not just in
your lower body.
Either supporting a barbell across your shoulders or holding dumbbells in each hand at your sides, place your feet shoulder-width apart pointing forward. Without letting your heels rise up from the floor, lower your body by bending at your knees until your thighs are slightly higher than parallel to the floor.
Your knees should point directly over, not beyond, your toes. Now dig your heels in, contract your abdominal muscles and push back up to the starting position. As with the deadlift, you need to straighten your legs and bring your torso back to perpendicular in one fluid, controlled motion.
Do not do this exercise unless the hack squat apparatus is on an angle. A perpendicular hack squat machine will put too much stress on your knees.
You perform this like a standard squat, only lower yourself until your thighs are parallel to the floor and don't lock your knees at the top. This is a great exercise for adding size and strength to your legs.
A fairly good alternative to squats is the leg press movement, which can be done on a wide variety of machines. Leg presses stress the quads and buttocks intensely, but place much less stress on the rest of the body than squats. Place your feet about a hip width apart, on the base of the leg press machine. Allow the weight to come down toward your chest until your knees form a 90 degree angle. Come down as deep as you can without raising your buttocks off the machine or letting your knees fan out to the sides. Then dig your heels into the platform and push the weight back up until your legs are just short of the locked-out position. Keep your shoulders down and don't tuck your chin. As well as the quadriceps the leg press works the following muscle groups: gluteus maximus, and to a lesser extent the hamstrings and the calves.
Leg Press Demonstration
Step under a barbell that's positioned on a rack and let it rest across your shoulders. If you are using a Smith machine there is less emphasis on balancing the weight; therefore, you can stagger your feet slightly without worrying about falling forward or backward. Execute the movement with your feet flat on the floor or with your heels slightly raised. Keeping your head up and your back straight, bend your knees and lower yourself until your thighs are parallel to the floor. Then push yourself up to the starting position, but don't bounce.
Smith Machine Demonstration
This exercise isolates the quadriceps. Place a barbell across your shoulders or holding a dumbbell in each hand, feet shoulder-width apart. Keep your upper body straight. Step forward and bend the leg as much as possible, keeping all your weight on it. Stand up by forcefully extending your front leg. Repeat with the other leg.
Sit on the seat of a leg extension machine, your feet hooked under the pads.
Extend your legs as far out as possible, flexing your thighs.
lower the weight just short of the starting position. But don't let the
weight drop. Repeat.