Objective: This study aims to investigate whether twelve weeks of FPT (MegaPower training) effectively accomplish patient-tailored participation and activity goals in ambulant children with CP, when compared to their usual care. Additionally, the goal is to investigate i) whether MegaPower training improves walking ability, aerobic endurance, and anaerobic capacity; ii) what factors best identify which ambulant children with CP benefit most from twelve weeks of MegaPower training; iii) to what extend the MegaPower training was implemented as intended in the participating study centers?, and iv) whether the effects of the MegaPower training are maintained after 12 and 24 weeks of follow-up. Study design: A single-blind randomized controlled parallel trial with a 24 week follow-up. During the follow-up, the control group will also receive MegaPower training. Study population: Ambulant children with cerebral palsy or a related non-progressive disorder between the ages of 4 - 12. Intervention: One group will receive twelve weeks of FPT (MegaPower training), whilst the other group will receive twelve weeks of usual care (control group). Main study parameters/endpoints: Accomplishment of patient-tailored participation and activity goals, measured through Goal Attainment Scaling.