Heel raises, or calf raises, work your calf. Your calves provide stability for your knee and ankle joints as well as power when you walk, run, or jump. You must train your calves using a variety of methods, and many types of raises work the different functions of your calf muscle. Consult your physician before beginning any diet or exercise program.
Your calf consists of two muscles -- the gastrocnemius and the soleus. The gastrocnemius muscle is the one that you can see on your calf, and it works to extend your foot and point your toe. The soleus, or smaller muscle under the gastrocnemius, works to extend your foot as well but also provides stability to the knee joint. The gastronemius is composed of primarily fast-twitch muscle fibers, which means it is strong but fatigues quickly. The soleus is composed of primarily slow-twitch muscle fibers, which means that it is not as strong but does not fatigue as quickly as the gastrocnemius.
Heel raises, or calf raises, work the gastrocnemius muscles of your calves. This exercise is done standing. You can use a standing calf-raise machine or a barbell. If you are using a barbell, you need to place the balls of your feet on a block of wood. To properly train your calves, you need a full range-of-motion, which means you need to allow your heels to descend to the limit of your flexibility. Single leg calf raises can be performed as well, often while holding a dumbbell in one hand.
Seated Calf Raises
The soleus is more active when your knee is bent. For this reason you should train the soleus in this manner. This normally requires a seated calf raise machine. After sitting on the seat, wedge your knees under the pad with the balls of your feet firmly in place. Point your toes until you are effectively on the balls of your feet, then lower the weight under control. This exercise is best performed with higher repetitions, usually in the 12-to-15 range. If you do not have a seated calf raise machine, you can sit down with the balls of your feet on a cinderblock. Place a barbell across your knees or balance a weight in some manner, then perform the exercise as you would with a machine.
Other Calf Work
Plyometric exercise, or rebound training, often is used to develop power in your calves. When running, at top speed your foot should not be in contact with the ground for more than 1/10 of a second, and this requires both strength and power. To train the stretch reflex of your calves, you can start by jumping rope. You do not need a fancy jump pattern or scheme; just get over the rope and land on the balls of your feet. Overtime, you can proceed to higher-intensity plyometric training, including depth jumps. These jumps involve jumping backwards off of a box and using the reflex strength of your calves to propel yourself back onto the box.