The research paper presents the case of a teenage girl with Hodgkin’s lymphoma (HL), investigating the effects of disease and treatment on muscle mass and function during and after therapy. Three factors—disease with treatment, physical exercise, and nutrition—were monitored over six months of therapy and six months afterward. Various methods were employed to collect and analyze data. Muscle function was assessed through periodic tests compared to a control group, and muscle mass was measured by BIA and DXA. The study showed that despite the cancer and aggressive treatment, the adolescent preserved muscle mass and function through proper nutrition and physical activity.