The purpose of this study was to investigate postural adjustments in one-handed ball catching. Specifically, the functional role of anticipatory postural adjustments (APA) during the initial arm raising and subsequent postural adjustments (SPA) for equilibrium control and ball-hand impact were scrutinized. Full-body kinematics and kinetics allowed an analysis of the mechanical consequences of raising up the arm and preparing for ball-hand impact. APA for catching were suggested to be for segment stabilization. SPA had a functional role for equilibrium control by an inverted pendulum mechanism but were also involved in preparing for the impact of the ball on the hand, which was illustrated by an increased postural response at the end of the movement. These results were compared with raising up the arm in a well-studied reaction-time task, for which an additional counter rotation equilibrium mechanism was observed. Together, our findings demonstrate that postural adjustments should be investigated in relation to their specific functional task constraints, rather than generalizing the functional role of these postural adjustments over different tasks.
Tijtgat, De Clercq and Lenoir are with the Faculty of Medicine and Health Sciences, Department of Movement and Sports Sciences, Ghent University, Gent, Belgium. Vanrenterghem and Bennett are with the Faculty of Science, Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Byrom Street Campus, Liverpool, UK. Savelsbergh is with the Faculty of Human Movement Sciences, Research Institute MOVE, VU University Amsterdam, Amsterdam, The Netherlands, and also the Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Manchester, UK.