Involuntary contraction of muscles of a particular area results in tightening of the muscle fibers that affects the blood flow to that location. This results in pain and discomfort and the condition is termed muscle spasm, which is mostly found to develop in the legs, back, shoulder, neck and arms. There are various contributory factors for this condition and these include, improper posture, prolonged sitting or standing, strenuous physical activities, dehydration, certain diseases and disorders and use of certain drugs.