In this experimental study, 60 office workers with trapezius myalgia are recruited from several work places with predominantly computer based tasks. Participants are required to perform at least 20 hours of computer work a week, and this since at least one year. Participants are included based on online questionnaires, a clinical examination of neck and shoulder, and the identification of a MTrP in the upper trapezius muscle. All participants will receive information and have to sign an informed consent form.