The calf muscles are made up of the gastrocnemius and soleus which elevate the heels when you contract them. This is an action that takes place when you stand on your toes to place something in a high cabinet or when you jump in the air to dunk a basketball. When problems take place in the calf muscles, you can have trouble getting around and the easiest of chores can become difficult.
The muscles are composed of thin layers of fibers that are woven together. When you play sports and overexert yourself or overtrain, you can suffer a pulled muscle, also known as a "strain." This causes the muscle to become torn or overstretched, causing pain. The calf muscles are a common area where this can happen being that they are always working when the heels are raising off the ground during running and jumping.
Muscles cramps are also commonly called "spasms" or "charley horses." In similar fashion to strains, these injuries can take place as a result of exercise, especially right after it is done or during the night. When these appear in the calves, the muscles suffer an involuntary, sudden contraction that can cause pain and a knot can appear. Dehydration and having a low level of electrolytes in your system can increase your chances of getting a cramp. The calves are prone to getting cramps for the same reason that strains appear; they get a heavy workload during running and jumping activities.
The plantaris muscle runs from the top of the knee to the bottom of the heel underneath the calf muscles. When the plantaris gets ruptured, it can cause pain, tenderness and inflammation in the calves. This injury can be characterized by a popping sound and feeling in the calf muscles.