(Muscle cramp) sudden, involuntary, painful contraction of muscles of the lower limb. It is caused by muscle fatigue, overexertion, dehydration, and depletion or imbalance of salt and minerals (electrolytes) such as Calcium, sodium, potassium and magnesium. A poor blood supply to leg muscles caused by smoking and atherosclerosis can cause claudication. Most common affected muscles are calf (gastrocnemius), hamstrings, and quadriceps. the cramp goes away within a few minutes or it can be treated by a gentle stretch and massage of the cramped muscle, pain relievers and muscle relxors.