What kind of leg exercises you do will, of course, depend on your goal. Are you trying to build massive thighs or heart-shaped calves? Do you want to build strength, increase running endurance or improve balance and flexibility? Are you a weight-lifter, a jogger or a ballerina?
Naturally, not all goals are mutually exclusive. Building strength can combine well with improving balance, for example. Having toned, strong leg muscles helps keep joints stable and improves appearance.
Remember that any strenuous exercise should be done only after a warm-up period that includes stretching.
One of the best exercises for toning and strengthening leg muscles is 'spinning', using a stationary bike. Using an ordinary bicycle is good too, but the exercise is less controllable and involves a lot of other muscle groups.
A 15-minute spin will help tone the calves, hamstrings and quads, improve joint flexibility and (sometimes) reduce cellulite and fat. It's also a great cardiovascular activity so you get two for the price of one when you spin.
If you want something a little less vigorous, say you only want to help strengthen the knee, here are a couple of options.
This first one is really good for those who suffer from conditions such as chondromalacia patella. That's a roughening of the cartilage underneath the knee cap, sometimes as the result of the bones not sitting properly in the 'V' of the knee joint.
Sit in a chair, back straight but not tensed. Your leg should be bent at 90 degrees, the thigh parallel to the ground, the lower leg vertical. Tense the thigh, hold for 5 seconds then release. Switch legs and repeat. Do 10 reps for each leg. Easy, huh!
Be sure to breathe normally during the exercise.
Another exercise does a little more to build strength in the muscles that control bending at the knee.
Sit up straight and breathe normally, then cross your legs at the ankle. Push forward with the rear leg and back with the front leg. (A little tricky at first, but think about it!)
Switch legs by reversing the direction of the cross. If the right leg was in front, move it to the rear. Repeat the exercise 10 times for each position.
Now for something a little more strenuous.
Depending on your balance and the surface you're standing on, you may need to do this on a mat or carpet, or on a wooden floor. Avoid using a cement or metal floor.
Stand up straight, heels together, toes slightly apart. Make sure you are well-balanced.
Lift the heels, balancing on the balls of your feet. Imagine a string attached to the center of your head pulling you up. Hold for 5 seconds, then lower slowly. Repeat 10 times. Over time, as you build strength and balance, increase the length of time you're on the balls of the feet.
Vary the action by bending slightly at the knee while you still have the heels raised. This will bring the thighs (quadriceps or 'quads' and hamstrings) as well as the buttocks into play. Straighten up, then lower the heels. Repeat 10 times.
Among the many health benefits of strong, flexible legs there is one that is especially important for the older crowd. Many falls lead to broken hips, one of the leading causes of severe health problems for the elderly. A long-term practice of keeping the legs in shape will help prevent this later in life.