It is also necessary to assess the EMG activity of the involved muscles to verify the early and increased protective muscle response suggested throughout the neural strain performance. Design: A matched case-control observational study. Objective: to check the increased upper limb mechanosensitivity by shoulder ROM during ULNT1 and to determine, for the first time, the evoked EMG muscle activity. Participants: 62 cases who underwent breast cancer surgery and 64 matched control women. Setting: Torrejon Hospital, Physical Therapy Department, Madrid (Spain). Intervention: To record EMG muscle activity during ULNT1 performance and to measure shoulder ROM. Key outcomes: mechanosensitivity, breast cancer, pain, EMG, shoulder ROM, median nerve.