Longitudinal Relationship between Physical Fitness , Walking-related Physical Activity and Fatigue in Children with Cerebral Palsy
Objective: A vicious cycle of decreased physical fitness, early fatigue and low physical activity levels (PAL) is thought to affect children with cerebral palsy (CP). However, the relationship of changes in physical fitness to changes in PAL and fatigue is unclear. The objective of this study was to investigate the relation between changes in physical fitness, walking-related PAL and fatigue in children with CP. Design: A secondary analysis of a randomized controlled trial with measurements at base-line, 6 months (after the intervention period) and 12 months. Participants: 24 children with bilateral and 22 with unilateral spastic CP, aged 7-13, all walking , participated in this study. Main Outcome Measures: Physical fitness was measured by aerobic capacity (VO 2 peak), anaerobic threshold, anaerobic capacity and, isometric and functional muscle strength. Walking-related PAL was measured using an ankle-worn StepWatch TM activity monitor for 1 week. Fatigue was determined with the PedsQL multidimensional fatigue scale. Longitudinal relationships were analyzed by random coefficient analysis (p < 0.05). Results: In children with bilateral CP, all fitness parameters showed a positive, significant relationship to walking-related PAL, whereas no relationship between physical fitness and walking-related PAL was seen in children with unilateral CP. No clinically relevant relationship between physical fitness and fatigue was found. Conclusions: Children with bilateral spastic CP might benefit from an improved physical fitness to increase their PAL or vice versa, while this is not the case in children with unilateral CP. There seems no relationship between physical fitness and self-reported fatigue in all children with CP. Interventions aimed at improving PAL may be differently targeted in children with either bilateral or unilateral CP. 7 Chapter Relations with fitness 119 INTRODUCTION It has been suggested that children with a physical disability may be trapped in a vicious circle of low physical fitness, early fatigue in daily activities and inactivity, resulting in decon-ditioning and a further decrease in physical activity.