Postural Adjustments in Catching: On the Interplay Between Segment Stabilization and Equilibrium Control

Abstract

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.

Emergent perception–action couplings regulate postural adjustments during performance of externally-timed dynamic interceptive actions

“…(Santos et al, 2010b;Tijtgat et al, 2013). Peak displacements in COP (Peak-COP) and each plane of COM, (Peak-COMx, Peak-COMy and Peak-COMz) and respective times were calculated (Time-to-peak-COP, Time-to-peak-COMx, Time-to-peak-COMy and Time-to-peak COMz) and used as an indication of postural control (Santos et al, 2010b).…”

“…Each trial was analysed from 300 ms before to 800 ms after T on (based on Tijtgat et al, 2013). All joint angles, centre of pressure (COP) and centre of mass (COM) are expressed relative to their baseline values (averaged between 500 and 300ms before T on ).…”

“…Existing research has often excluded advanced perceptual information in experiments (e.g. Eckerle, Berg, & Ward 2012;Kazennikov & Lipshits, 2010;Tijtgat et al, 2010Tijtgat et al, , 2012Tijtgat et al, , 2013 and typically, studies of catching behaviors have been designed so that participants are constrained to catch balls launched from a projection machine, to facilitate experimental control of flight trajectory. However, projection machines do not provide access to advanced visual information from a thrower's actions.…”

“…However, projection machines do not provide access to advanced visual information from a thrower's actions. For example, Tijtgat et al (2013) covered their machine with black plastic to ensure participants could not anticipate ball delivery. The removal of such informational constraints, although providing some experimental control, significantly alters the affordances (invitations for action; Gibson, 1979) available to a participant to regulate their actions.…”

“…External perturbation can shift the projection of the COM closer to the borders of the base of support and the alignment between the COM and COP is disrupted, which may result in the loss of body equilibrium (Santos et al, 2010). Postural regulation is required when catching a passing ball, both to counter effects of raising an arm upwards and towards the object in space, but also to adjust against potential disequilibrium caused by the mechanical impulse of an approaching projectile acting on the hand (Tijtgat et al, 2013;Williams & McCririe, 1988). Indeed, previous research has shown that poor catchers were able to achieve the performance level of good catchers when additional support for postural control was provided to reduce the number of motor system degrees of freedom that need to be coordinated in a synergy (see Angelakopoulos, Davids, Bennett, Tsorbatzoudis, & Grouios, 2005;Davids, Bennett, Kingsbury, Jolley, & Brain, 2000;Savelsbergh, et al, 2005).…”