Vol.:(0123456789) 1 3 Experimental Brain Research https://doi.org/10.1007/s00221-020-05772-4 RESEARCH ARTICLE Persons in remission from recurrent low back pain alter trunk coupling under dual‑task interference during a dynamic balance task K. Michael Rowley 1  · Carolee J. Winstein 1  · Kornelia Kulig 1 Received: 28 September 2019 / Accepted: 4 March 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract This study investigated efects of cognitive dual-task interference and task prioritization instructions on task performance and trunk control during a dynamic balance task in persons with and without recurrent low back pain (rLBP). First, we tested the hypothesis that those with rLBP rely more on cognitive resources than back-healthy controls, and therefore trunk kinematics would be altered under dual-task interference conditions. Then, we tested participants’ ability to modulate task performance in accord with prioritization instructions. Persons with and without rLBP (n = 19/group) performed the Balance-Dexterity Task, which involved single-limb balance while compressing an unstable spring with the other limb, with and without a cognitive task engaging verbal working memory. Trunk coupling was quantifed with the coefcient of determination (R 2 ) of an angle–angle plot of thorax–pelvis frontal plane motion. Task performance was quantifed using variability of spring compression force and of cognitive task errors. Trunk coupling in the rLBP group was lower than that of the back-healthy control group in the single-task condition (p = 0.024) and increased in the dual-task condition (p = 0.006), abolishing the diference between groups. Signifcant main efects of task prioritization instruction on performance were observed with no diferences between groups, indicating similar performance modulation. Cognitive task error variability decreased with a switch from a single- to dual-task condition, exposing an unexpected facilitation efect. We interpret these fndings in the context of movement-specifc reinvestment and action-specifc perception theories as they pertain to cognitive contributions to posture and how the dual-task interference paradigm may infuence those contributions. Keywords Trunk · Balance · Dual task · Paraspinal · Task difculty · Cognitive task Introduction Attentional resources utilized for postural control have been studied with dual-task interference paradigms in non-disa- bled adults and diverse special populations. Investigating the role of cognition and attentional processes in motor control dysfunction in clinical populations can provide insight into fundamental features of cognition and motor control and guide development of improved interventions for these pop- ulations. In persons sufering from chronic or recurrent low back pain (rLBP) specifcally, alterations in the dynamics of posture–cognition prioritization are important for informing restorative interventions. This is highlighted by recent calls for investigations into the role of attentional processes and psychometrics in this clinical population (van Dieën et al. 2018a, b; Brumagne et al. 2019). Unfortunately, research into the efects of dual-task interference in persons with rLBP is limited, and fndings are mixed. This stems, in part, from the nature of both the motor tasks and the cognitive tasks being used (Fraizer and Mitra 2008; Reeves et al. 2019; Rowley and Kulig 2019). Much of what we know about cognitive processes in per- sons with residual motor control dysfunction from a previous episode of rLBP comes from investigations using discrete perturbations to posture like an arm fexion task (Hodges 2001). While discrete perturbations like this provide well- controlled inputs to the control system, our group reasoned that studies of continuous functional tasks would provide insight into more ecological, dynamic motor control chal- lenges (Rowley and Kulig 2019; Rowley et al. 2019). There Communicated by John C. Rothwell. * K. Michael Rowley kmichaelrowley@pt.usc.edu 1 Division of Biokinesiology and Physical Therapy, University of Southern California, 1540 Alcazar St, CHP-155, Los Angeles, CA, USA