Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Myotonia ?
    ### Response:
    Myotonia is a medical term that refers to a neuromuscular condition in which the relaxation of a muscle is impaired. It can affect any muscle group. Repeated effort will be needed to relax the muscle, although the condition usually improves after the muscles have warmed-up.
    