Laura Peeters

50 | Chapter 3 which trunk segment movements should be allowed to move or be supported when performing daily activities. Therefore, our aim was to obtain more insight in the interaction of trunk, head and arm movements in healthy children with a specific focus on the segmental nature of the trunk. METHODS Participants Twenty-five healthy children and young adults (13 males, 6-20 years) participated in this study. The subjects were evenly distributed over the age range. None of the participants had a history of disorders affecting movement of the upper body. In addition, they had no scoliosis and no pain in arm(s), trunk, neck or head at the time of participation. Participants were recruited from local primary schools, high schools and university. Prior to participation, informed consent was given by participants when over 12 years old, and by the children’s parents or guardians for all participants younger than 18 years old. The study was approved by the medical ethics committee Arnhem- Nijmegen (NL53143.091.15) and all data were handled according to the guidelines of good clinical practice. Experimental setup All subjects were seated on a height adjustable chair with a multi-celled air cushion (Starlock, Star Cushion Products, Freeburg, IL), without back- or armrests. Before the measurement, the cushion was formed to each individual shape by releasing air to provide some additional sitting stability and comfort. The sitting height was adjusted so that the knees were flexed 90° and both feet were flat on the ground. First, subjects were asked to perform a maximum flexion movement of their trunk from a seated position, immediately followed by a maximum extension movement of their trunk (keeping both feet on the ground). They were instructed to move from the upright position to the maximum position at a slow pace (three seconds) and repeated this flexion-extension movement three times. The same was done for maximum axial rotation and lateral bending. The arms were crossed at the chest when performing the flexion-extension and rotation task, and were rested on the upper legs when performing the lateral bending task. No instructions were given regarding pelvis or hip movement. Subsequently, movements were repeated for the