To effectively build muscle mass you will need to do several intensive lifting workouts per week. The best way to avoid over straining your muscles is to focus only on either the upper body or lower body in one session.

Here is a compilation of the best muscle building exercises for your lower body:

Deadlift:

Body Position - Provide a solid base by placing your feet marginally further apart than your shoulders. The bar of the weights needs to be resting across the balls of your feet. Look straight forward and squat. Make sure you keep your back straight to avoid injury. Position your hands a little wider than your feet, and firmly hold the bar with both hands.

The Lift - Keep your back and arms completely straight and lift the bar. Your aim is to work your leg muscles - which will be providing the power. If you feel pressure and pain in your back, your technique is incorrect. If your back is not completely straight you risk damaging your disks. When you have achieved an upright position, raise the bar up from the shoulders and the lift is complete.

Completion - Use precision and control to return the weights to the floor. Your back should be rigid, and you should use your hips and knees to lower your body.

Squats:

Body Position - Firstly, you should position the bar of the weights approximately 3 inches lower than the highest point of your trapezius. Back up to the bar, and provide a solid base by placing your feet marginally further apart than your shoulders. Place your hands on the bar at a comfortable distance apart.

The Lift - It is critical to look straight when you do this exercise, because shifting your focus can lead to a nasty fall. Your torso should be rigid, and you should bend your knees to lower your body.

Completion - Use precision and control to rise from your knee bend into the standing position again. Your hips and knees should be extended, and your focus should be on controlling the bar's motion.

Lunges:

Body Position - Take a stride, maintain the position, and move your feet slightly further apart. A straight line should form between your front knee and front foot. To use this exercise to its fullest extent, add dumbbells in both hands.

Movement - Bend your front knee thus lowering your back knee towards the floor. Avoid the temptation to lean forward by focusing straight in front, and keeping your chin up.

Completion - Straighten your legs and return to your original position. You should tightly squeeze your buttocks and use your abdominal muscles and lower back muscles to keep your upper body rigid.

Leg Press:

Body Position - Use the leg press machine for this exercise. Sit comfortably in the seat with your back straight. Place your feet a little more than shoulder width apart, and stabilize them by using the footpad provided. Ensure that your legs form an angle of around 100 degrees before you begin.

Movement - Use your heels to push off from the footpad and straighten your legs without locking them. If you use the balls of your feet instead of your heels, you will risk injury.

Completion - Restore your legs to their original position by using a carefully controlled, gradual motion.

Calf Raises:

Body Position - If your intention is to use a calf raise machine, put your feet on the pads provided, and position your shoulders properly with the shoulder pads. If you are using free weights, hold them securely and put your toes on the edge of your block.

Movement - Using the balls of your feet, carefully move your body in an upwards direction. Keep your knees straight, and use the motion provided by your ankle.

Completion: Using precision and control lower your body until your heels are only slightly elevated from the floor.

Leg Extension:

Body Position - Use the leg curl machine for this exercise. Seat yourself and place your legs over the bar which will lie in a resting position behind your knees - forming a 90 degree angle. Tuck your feet behind the other padded bar which should lie over your ankles. Remember that the height of this second bar will determine how far you are moving the weight. Further down = more valuable muscle mass.

Movement - Extend your legs in a kicking motion without locking your knees.

Your calf muscles and the floor should be parallel.

Completion - Return your legs to their original position using a fluid, controlled movement with no jerking. Lowering the weight is as important as elevated in to build your muscle mass.