Influences of Postural Control on Cognitive Control in Task Switching

Sitting vs. standing: an urgent need to rebalance our world

During their activities of daily living, humans run, walk, stand, sit and lie down. Recent changes in our environment have favored sedentary behavior over more physically active behavior to such a degree that our health is in danger. Here, we sought to address the problem of excessive time spent seated from various theoretical viewpoints, including postural control, human factors engineering, human history and health psychology. If nothing is done now, the high prevalence of sitting will continue to increase. We make a case for the standing position by demonstrating that spending more time upright can mitigate the physiological and psychological problems associated with excessive sitting without lowering task performance and productivity. The psychological literature even highlights potential benefits of performing certain tasks in the standing position. We propose a number of recommendations on spending more time (but not too much) in the standing position and on more active, nonambulatory behaviors. There is a need to inform people about (i) harmful consequences of excessive sitting and (ii) benefits of spending more time performing active, nonambulatory behaviors. One clear benefit is to reduce detrimental health consequences of excessive sitting and to provide potential additional benefits in terms of productivity and performance.

Assessing the influence of cognitive response conflict on balance control: an event-related approach using response-aligned force-plate time series data

Process interference or sharing of attentional resources between cognitive tasks and balance control during upright standing has been well documented. Attentional costs increase with greater balancing demands of a balance activity, for example in standing compared to sitting. The traditional approach for analyzing balance control using posturography with a force plate integrates across relative long trial periods of up to several minutes, which blends any balance adjustments and cognitive operations within this period. In the present study, we pursued an event-related approach to assess if single cognitive operations resolving response selection conflict in the Simon task interfere with concurrent balance control in quiet standing. In addition to traditional outcome measures (response latency, error proportions) in the cognitive Simon task, we investigated the effect of spatial congruency on measures of sway control. We expected that conflict resolution in incongruent trials would alter short-term progression of sway control. Our results demonstrated the expected congruency effect on performance in the cognitive Simon task and the mediolateral variability of balance control within 150 ms before the onset of the manual response was reduced to a greater degree in incongruent compared to congruent trials. In addition, mediolateral variability before and after the manual response was generally reduced compared to variability following target presentation, where no effect of congruency was observed. Assuming that response conflict in incongruent conditions requires suppression of the incorrect response tendencies, our results may imply that mechanisms of cognitive conflict resolution may also carry over to intermittent balance control mechanisms in a direction-specific manner.

The effect of dual-task conditions on postural control in adults with low back pain: a systematic review and meta-analysis

BACKGROUND

Dual-task conditions, which involve performing two tasks simultaneously, may exacerbate pain and further impair daily functioning in individuals with low back pain (LBP). Understanding the effects of dual-task conditions on postural control in patients with LBP is crucial for the development of effective rehabilitation programs. Our objective was to investigate the impact of dual-task conditions on postural control in individuals with LBP compared to those without LBP.

METHODS

We conducted a comprehensive search of Medline via PubMed, Scopus, the Cochrane Central Register of Controlled Trials, Web of Science, and EMBASE databases, with no language restrictions, from inception to January 1, 2023. The primary outcome measures of the study were velocity, area, amplitude, phase plane portrait, and path/sway length of the center of pressure (CoP). Standardized mean difference (SMD) effect sizes were calculated, and the quality of the studies was assessed using the Newcastle-Ottawa Scale (NOS).

RESULTS

From 196 studies, five involving 242 adults (≥ 18 years) met the inclusion criteria. Three studies were rated as high quality, while two were deemed moderate. In the included studies, 140 participants had non-specific LBP, while 102 participants did not report any symptoms, with mean ages of 36.68 (± 14.21) and 36.35 (± 15.39) years, respectively. Three studies had both genders, one exclusively included females, and one did not specify gender. Meta-analyses of primary outcomes revealed no significant differences in postural control between patients with LBP and pain-free controls during both easy and difficult postural tasks and cognitive load for velocity (easy: SMD - 0.09, 95% CI - 0.91 to 0.74; difficult: SMD 0.12, 95% CI - 0.67 to 0.91), area (easy: SMD 0.82, 95% CI - 2.99 to 4.62; difficult: SMD 0.14, 95% CI - 2.62 to 2.89), phase plane (easy: SMD - 0.59, 95% CI - 1.19 to 0.02; difficult: SMD - 0.18, 95% CI - 0.77 to 0.42), path/sway length (easy: SMD - 0.18, 95% CI - 0.77 to 0.42; difficult: SMD - 0.14, 95% CI - 0.84 to 0.55), and amplitude (easy: SMD 0.89, 95% CI - 1.62 to 3.39; difficult: SMD 1.31, 95% CI - 1.48 to 4.10).

CONCLUSIONS

The current evidence suggests that there are no significant differences in postural control parameters during dual-task conditions between individuals with non-specific LBP and pain-free subjects. However, due to the limited number of available studies, significant publication bias, and considerable statistical heterogeneity, definitive conclusions cannot be drawn. Therefore, further research comprising high-quality studies with larger sample sizes is necessary to obtain conclusive results. Trial registration PROSPERO CRD42022359263.

Benefits associated with the standing position during visual search tasks

The literature on postural control highlights that task performance should be worse in challenging dual tasks than in a single task, because the brain has limited attentional resources. Instead, in the context of visual tasks, we assumed that (i) performance in a visual search task should be better when standing than when sitting and (ii) when standing, postural control should be better when searching than performing the control task. 32 and 16 young adults participated in studies 1 and 2, respectively. They performed three visual tasks (searching to locate targets, free-viewing and fixating a stationary cross) displayed in small images (visual angle: 22°) either when standing or when sitting. Task performance, eye, head, upper back, lower back and center of pressure displacements were recorded. In both studies, task performance in searching was as good (and clearly not worse) when standing as when sitting. Sway magnitude was smaller during the search task (vs. other tasks) when standing but not when sitting. Hence, only when standing, postural control was adapted to perform the challenging search task. When exploring images, and especially so in the search task, participants rotated their head instead of their eyes as if they used an eye-centered strategy. Remarkably in Study 2, head rotation was greater when sitting than when standing. Overall, we consider that variability in postural control was not detrimental but instead useful to facilitate visual task performance. When sitting, this variability may be lacking, thus requiring compensatory movements.

Coupling of sensorimotor and cognitive functions in middle- and late adulthood

Introduction

The present study explored age effects and the coupling of sensorimotor and cognitive functions in a stratified sample of 96 middle-aged and older adults (age 45-86 years) with no indication of mild cognitive decline. In our sensorimotor tasks, we had an emphasis on listening in noise and postural control, but we also assessed functional mobility and tactile sensitivity.

Methods

Our cognitive measures comprised processing speed and assessments of core cognitive control processes (executive functions), notably inhibition, task switching, and working memory updating. We explored whether our measures of sensorimotor functioning mediated age differences in cognitive variables and compared their effect to processing speed. Subsequently, we examined whether individuals who had poorer (or better) than median cognitive performance for their age group also performed relatively poorer (or better) on sensorimotor tasks. Moreover, we examined whether the link between cognitive and sensorimotor functions becomes more pronounced in older age groups.

Results

Except for tactile sensitivity, we observed substantial age-related differences in all sensorimotor and cognitive variables from middle age onward. Processing speed and functional mobility were reliable mediators of age in task switching and inhibitory control. Regarding coupling between sensorimotor and cognition, we observed that individuals with poor cognitive control do not necessarily have poor listening in noise skills or poor postural control.

Discussion

As most conditions do not show an interdependency between sensorimotor and cognitive performance, other domain-specific factors that were not accounted for must also play a role. These need to be researched in order to gain a better understanding of how rehabilitation may impact cognitive functioning in aging persons.

Does body posture reduce the Stroop effect? Evidence from two conceptual replications and a meta-analysis

Standing compared to sitting, for instance at work, is associated with positive physical and mental health consequences. Indeed, studies suggest that performance in cognitive conflict tasks (e.g., Color Stroop tasks) is improved when subjects perform the task while standing compared to sitting (Rosenbaum et al., 2018; Smith et al., 2019). However, a recent study failed to replicate these findings in five attempts (Caron et al., 2020). We aimed to shed light on these discrepant results by means of two conceptual replications and a meta-analysis. Replication experiments showed typical congruency effects in the Color Stroop task, but failed to find any influence of posture on the Stroop effect even when we subjected data to a more sensitive analysis that controlled for individual variances between participants. Additionally, an explorative Bayesian analysis confirmed that both replications provided strong evidence against an interaction between body posture and the Stroop effect. Meta-analytic results showed that the confidence interval of the overall effect size for a modulation of the Stroop effect by body posture includes the null. Together, our results question whether standing modulates the Stroop effect in Color Stroop tasks and points out limitations of the influence of body posture on cognitive control tasks.

The Effects of Cognitive Task and Change of Height on Postural Stability and Cardiovascular Stress in Workers Working at Height

The purpose of the study was to analyze the effects of cognitive task and change of height on the postural stability and cardiovascular stress of at-height workers. The study included 32 healthy men aged 25-47. Due to the type of work performed, two groups were identified: at‒height workers, HW (n = 16), and office workers (mainly work at desk with a computer) OW (n = 16). The objective measures of postural stability (posturography) and cardiovascular stress (heart rate monitor) were evaluated for both groups at two different platform heights (ground level and 1 m above the ground) with or without cognitive task (backward counting). The increased height and the cognitive task were found to significantly affect measures of postural stability and cardiovascular stress. It was observed that in inexperienced OW employees, higher platform height and performing a cognitive task meant that posture stability significantly decreased, while cardiovascular stress and difficulties in maintaining balance increased. In HW group postural stability is less affected by distress conditions than in OW group.