Laura Peeters

76 | Chapter 4 spinal fusion surgery. DMD participants were recruited through advertisements by two patient organizations (Duchenne Parent Project and Spierziekten Nederland) and through the outpatient clinic of the Radboudumc in Nijmegen. HC were recruited from local primary schools, high schools and university. Prior to participation, written 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. Procedures We used the same procedure as the one employed in a previous study with healthy children [10]. All participants were seated on a height adjustable chair with a multi- celled air cushion (Starlock, Star Cushion Products, Freeburg, IL), without back- or armrests. The sitting height was adjusted so that the knees were flexed 90° and both feet were flat on the ground. First, to determine maximum trunk range of motion, participants were asked to perform a maximum active flexion movement of their trunk from a seated position, immediately followed by a maximum active extension movement of their trunk (keeping both feet on the ground). The same was done for maximum axial rotation and lateral bending. Thereafter, a series of tasks were performed with the dominant hand at a self-selected speed. Several reaching (and placing) tasks were performed at shoulder height: reaching forward, sideways and contra-laterally at a 45 degrees angle in the transverse plane. Participants had to touch a reference frame positioned at the desired position, or to place an object on the reference frame. Reaching distance and object weight were varied, resulting in the following combinations for forward, lateral and contra-lateral reaching: nearby-0 gram (“N-0”), nearby-500 gram (“N-500”), far- 0 gram (“F-0”). Contra-lateral reaching was not performed at a far distance. Nearby was defined as the distance that could be reached by stretching the arm (i.e. 100% arm length for HC, but could be closer for DMD) and far as 133% of arm length when possible, otherwise as maximum reaching distance. Arm length was defined as the distance from mid-acromion to the centre of the hand . Furthermore, subjects were asked to perform two daily tasks: displace a porcelain plate (circa 600 grams) from left to right on a table with both hands (“Plate”) and bring a cup of 200 grams to the mouth (“Drink”). The drink task was based on the instructions of the Performance of the Upper Limb [11]. No instructions were given on how to perform the tasks.