Involuntary muscle contractions, also known as spasms, are sudden, involuntary movements of the body caused by a muscle's contraction. These contractions can be painful and can affect any muscle in the body, including those in the arms, legs, back, and abdomen. Spasms can be caused by a variety of factors, including stress, dehydration, and certain medical conditions. Treatment for spasms typically involves stretching, massage, and medications to reduce pain and inflammation.