"Exercise Intervention to Increase Physical Activity in Young Sarcoma Survivors (Sport Ist Herzenssache)"

Survivors of bone and soft tissue sarcoma often face long-term health problems after their cancer treatment, such as muscle weakness, joint stiffness, and reduced heart and lung fitness. Because of this, many survivors are less physically active than their healthy peers, which can further increase their risk of heart disease and other late effects later in life. This study, called "Sport ist Herzenssache" ("Sports is a Matter of the Heart"), tests whether a personalized exercise program can help young survivors (aged 15-39) become more physically active. All participants receive a fitness tracker (smartwatch) to monitor their daily activity. Half of the participants are randomly assigned to also receive an individualized home exercise plan, including strength and endurance training, with some sessions guided online by an exercise specialist. Before and after an 8-week exercise period (with continuous activity tracking for about 13 weeks total), participants complete simple physical tests (such as walking and balance tests), a heart and fitness check-up, and questionnaires about their quality of life and energy levels. The main goal is to find out whether the personalized exercise plan helps participants become more active in daily life, measured in minutes of moderate-to-intense activity per day. The study also looks at effects on heart health, physical function, and overall well-being. The results will help determine whether structured exercise support should become a standard part of long-term follow-up care for young sarcoma survivors.

Inclusion Criteria: * Diagnosis of bone or soft tissue sarcoma * Currently receiving follow-up care at the tumor orthopedics clinic of University Hospital Essen * Age ≥15 and ≤39 years at time of enrollment * Completion of local tumor therapy (surgery and/or definitive radiotherapy) more than 12 months prior to enrollment * Access to a smartphone for data synchronization with the wearable device Exclusion Criteria: * Contraindications to physical activity * Language barriers preventing communication in German * Known or current psychiatric condition impairing the ability to understand study requirements, participate in the study, or provide informed consent * Pregnancy * Planned absence of more than 2 weeks during the study period (e.g., due to rehabilitation stays) * Pre-existing average MVPA \>60 minutes/day at baseline