Chemotherapy-related pain is a well-known side effect in cancer patient receiving chemotherapy. However, limited knowledge exists describing whether exercise exacerbates existing pain. Aim of the research was to explore muscle and joint pain experienced by women with breast cancer receiving adjuvant chemotherapy with epirubicin and cyclophosphamide followed by docetaxel and factor support and concurrently participating in an exercise intervention. The study used individual semi-structured interviews (pre- and post-intervention). Fifteen women were interviewed. The multimodal group intervention comprised supervised training: high-intensity cardiovascular, heavy resistance and relaxation, massage and body-awareness (9 h weekly, 6 weeks). The analysis revealed five categories: Abrupt pain - a predominant side effect, cogitated pain management, the adapted training, non-immediate exacerbation of pain and summarised into the essence of chemotherapy related muscle and joint pain in exercise breast cancer patients; exercise despite pain. Findings indicate that the patients' perception of sudden onset of chemotherapy-related muscle and joint pain was not aggravated by training. Pain intensity peaked between 2 and 9 days after chemotherapy and is described to be stabbing pain with a feeling of restlessness in the body. The patients demonstrated a high adherence rate to the exercise intervention caused by their own willpower and camaraderie of the group.