Over the last decade, a major shift in pediatric rehabilitation to activity-based interventions with a focus on improving fitness, physical activity, and participation for children and youth with disabilities has transpired. A catalyst for this shift is the emphasis on health promotion and disease prevention in the health care arena.

As rehabilitation intervention protocols incorporate more strategies to increase fitness, physical activity, and participation in children and youth with disabilities, it is critical to make certain that outcome measures are appropriate to examine intervention effectiveness. There has been increased research in measurement methodology to ensure the feasibility, reliability, validity, and responsiveness of fitness and physical activity measures for children and youth with disabilities, specifically cerebral palsy. It is important that pediatric rehabilitation researchers design sound intervention and measurement protocols to identify the effectiveness of activity-based interventions to improve fitness and physical activity in children and youth with disabilities. It is important that these measures are accessible and feasible for researchers (laboratory based) and clinicians (field based). Further, it is important that researchers articulate clear operational definitions of the fitness components (strength, endurance, flexibility, and body composition) and physical activity dimensions (frequency, duration, and intensity) that are being examined in the research. This special issue presents an international forum for pediatric rehabilitation researchers to present their most current research findings on fitness and physical activity intervention and measurement protocols for children and youth with disabilities. Potential topics include, but are not limited to:

• Aerobic and anaerobic fitness interventions
• Aerobic and anaerobic fitness measures
• Strengthening interventions
• Strength measures
• Physical activity interventions
• Physical activity measures

Before submission authors should carefully read over the journal's Author Guidelines, which are located at http://www.hindawi.com/journals/ijped/guidelines/. Prospective authors should submit an electronic copy of their complete manuscript through the journal Manuscript Tracking System at http://mts.hindawi.com/ according to the following timetable: