Because the leg muscles are the largest in the body, building these muscles raises the metabolism. A raised metabolism means the body burns more calories even when resting and so benefits weight loss. All aerobic exercises improve leg muscles. Aerobic activities like walking, running, jogging, skiing, tennis, football and most ball games build and tone leg muscles. Exercises like lunges, squats and leg extensions target specific muscles and should be included as part of an overall exercise workout.

Normal daily activity requires the use of leg muscles. Unless you are very active, 3-4 overall body workouts each week is sufficient and about 15 minutes per session doing specific leg exercises.

Lunge

The lunge can be performed without weights (i.e, bodyweight). However, weight trainers usually seek to increase the difficulty using either dumbbells (held in each hand) or a barbell with weights on it (held atop the neck and shoulders)

• Stand with feet shoulder-width apart, arms at your sides.
• Inhale and take a large step backward with the left foot to a point where your left knee is a few inches above the floor (or as close as you can comfortably go) and your right knee does not extend past the toes of your right foot.
• Your hands, with or without dumbbells, remain at your sides; your gaze is forward.
• Exhale and step forward with the left leg returning to the starting position.
• Finish all reps with the left leg before repeating with the right.
• To make the movement less difficult, alternate legs.
• Repeat to muscle fatigue (in the range of 12 to 20 reps).

Step-Ups

While step-ups are a great toning exercise, they also serve as a warm up for squats and lunges, and should therefore be done in a higher rep range with no added resistance.

• Place your right foot flat on the step and your left foot flat on the floor.
• Exhale and push off as little as possible with the left foot as you bring both feet up to step level (you’ll now have two feet on the step). Inhale and lower your left foot back down to the floor.
• Work with body weight only, and repeat to muscle fatigue regardless of the number of reps.
• Repeat with the legs reversed.

Squat

Squats are considered a vital exercise for increasing the strength and size of the legs and buttocks.

• Stand with your feet shoulder-width apart holding your hands or dumbbells at your sides.
• Your head is straight, the natural arch maintained in your back.
• Inhale, swing the weights (or your bare hands) slightly forward for balance while bending at the knees and hips to a sitting position (or as low as you can go and still maintain balance).
• Be sure the buttocks don't drop below the level of your knees, and your knees do not extend past your toes.
• Exhale and slowly return to a standing position, allowing your hands to drop back down to your sides.
• Repeat to muscle fatigue (in the range of 12 to 20 reps).

Source: Bombay Times