Immediately following the UC period, children were enrolled into a predefined intervention program (IP), designed by the first and third author of the study. The programs will be executed by the child's personal physical therapist, who will agree to precisely follow the prescribed program. Similar as for the UC program, the children will receive the frequency of therapy as they usually receive by their own private physical therapist. Two different types of programs were designed. Ten children received an individually defined, targeted program tailored to the individual needs of the child and six children received a general program based on general age-appropriate treatment aims for children with bilateral spastic CP. For an extensive description of the differences and similarities between both types of intervention programs, the authors refer to our previous intervention studies. All intervention programs have two major common features. The first central and common aspect in the intervention programs was that basic principles regarding evidence-based training were respected. All programs consist of a predefined set of exercises to improve strength, selectivity and mobility and a set of functional exercises. Thereby, stretching is prescribed as three repetitions of 30 seconds and strength training was prescribed in series of three times 12 to 15 repetitions. Functional exercises are not restricted to a specific repetition number. As appropriate, all intervention programs will contain more than 50% of exercises at activity and participation level. The second major common feature in the intervention programs is the support and follow-up to the therapist. At the start of the intervention study, therapists will be visited and the prescribed program will be thoroughly explained. All exercises will be provided in a clear and structured way, with specific instructions regarding anatomical position, sets and repetitions. The specific exercises will be discussed and demonstrated if necessary. During the second or third week, the therapist will be contacted by phone or email to discuss the progress of the program and the possible needs to change and adjust exercises. Additionally, a follow-up visit will be organized around halfway through the program. During this visit, the program will again discussed and the therapist performed a regular therapy session using the program, in attendance of the first author of the study. Difficulties in performance were discussed and if necessary, some exercises were demonstrated. The opportunity for feedback on handling or position was thereby provided.