The main aim of this project is to gain knowledge about the muscle-tendon pathology of moderately to severely affected young people with cerebral palsy and their risk for cardiometabolic diseases and chronic inflammation. Furthermore, it will be investigated whether there are associations between the existing pathophysiology as well as inactivity and muscle function, cardiometabolic risk factors and inflammation. Moreover, the potential of the target group for adaptation of its muscular, cardiorespiratory, and endocrine system will be investigated. The study parameters will be determined in adolescents and young adults aged 14 to 30 years with moderate to severe spastic cerebral palsy and compared with those of their less severely affected and healthy peers (cross-sectional study). In addition, the more affected individuals will participate in a 12-week training intervention (longitudinal study) performed with special tricycles (i.e., Frame Runners). To measure the study parameters, ultrasound, strength tests, near-infrared spectroscopy, blood analyses, and spiroergometry will be used. The fitness training will be performed two times a week for 12 weeks with the Frame Runners.