Muscle Cramp and Commonly Affected Muscles
A muscle cramp is an involuntary and sudden contraction of muscles in the body. This condition is mostly harmless, but it would lead to severe pain in the affected area. As a result, you would find it temporarily impossible to move some parts of the body. Extended periods of physical activities or exercises, especially in hot weather, may cause muscle cramps in many individuals. Certain drugs and medical conditions would increase the risk as well. Fortunately, you can manage the symptoms with some self-care measures at home. 
Most muscle cramps are involuntary and sudden contractions of the body’s muscles. They may be mild or very painful, depending on the underlying cause and affected area. Although this condition could occur to any skeletal muscle, they tend to be more common in the feet, legs, and muscles crossing two joints. One or more muscles in a single group can be involved in a muscle cramp. These include the abdomen, arms, hands, feet, quadriceps, hamstrings, or back of the lower leg.