Upper limb neural mechanosensitivity is a painful disturbance that breast cancer patients often undergo following axillary surgery. It is assessed by the upper limb neurodynamic test for the median nerve, called upper limb neurodynamic test 1 (ULNT1). Design: A matched case-control observational study. Objective: to check the increased upper limb mechanosensitivity by shoulder range of motion (ROM) during ULNT1 and to determine, for the first time, the evoked electromyographic (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.