Detrimental Effects of Effortful Physical Exertion on Cognitive Control in Younger and Older Adults

Abstract

Research assessing the effects of age on physical actions and cognitive processes is often conducted in isolation. However, action and cognition often interact in daily functions and deteriorate with age. Therefore, assessing how motor actions affect core cognitive abilities and how age amplifies these effects is pivotal. The present study tested the effects of effortful physical exertion (isometric handgrip) on working memory (WM) and inhibitory control in young and older adults. Using a novel dual-task paradigm, participants engaged in a WM task with 0 or 5-distractors under concurrent physical exertion (5% vs 30% individual maximum voluntary contraction, MVC). Given our previous understanding that high physical exertion impairs inhibitory control, we hypothesized 1) inhibitory control of access to WM will be compromised under high physical exertion and 2) this effect will be amplified by age. Effortful physical exertion, although failed to affect WM accuracy with 0-distractors present for both age groups, reduced WM accuracy for the older, but not young adults, with 5-distractors present. Similarly, older adults experienced greater distractor interference with 5-distractors present under high physical exertion, indexed by slower reaction time (RT), confirmed by hierarchical Bayesian modeling of RT distributions. Our findings that a simple but effortful physical task may result in impaired cognitive control may be empirically important for understanding everyday functions of older adults. Reduced inhibitory control and physical abilities may pose a problem for older adults as the negative interactions between cognitive and motor tasks may impair daily functions and possibly increase the risk of injury.

Effortfulness of visual working memory: Gauged by physical exertion.

“…As a result, when the number of WM items increases from smaller to larger set sizes (e.g., set size 6), the direct comparison between physical load and cognitive task performance becomes more obvious as supported by a significant physical load by WM set size interaction effect in Experiment 3. Recent evidence showing that concurrent physical exertion could impact control-related task performance in visual search and visual WM tasks with an increased number of distractors appears to be in line with this interpretation (Azer et al, 2022;Park et al, 2021). In light of these findings, shared effort-related representations and processes across modalities may be rooted in the mechanisms involved in cognitive control (Kool & Botvinick, 2018;Shenhav et al, 2017).…”

“…Supporting this conjecture, we find that concurrent physical exertion impacts visual WM task performance only at a large set size, where the task demand on cognitive control is high. Yet, this prediction entails further investigation, such as testing the effect of concurrent physical exert on distractor inhibition in visual WM (Azer et al, 2022).…”

Effortfulness of Visual Working Memory: Gauged by Physical Exertion

“…This distinction has been previously discussed (Shenhav et al, 2017), because physical and WM tasks could draw on the same pool of limited WM capacity (Kafry & Kahneman, 1977;Navon & Miller, 2002;Tombu & Jolicoeur, 2003) such that physical exertion can reduce the total amount of information one can simultaneously retain in WM. We find this explanation unlikely, given a recent finding that a concurrent physical load mainly reduces control efficiency in visual WM without reducing its overall storage capacity (Azer et al, 2022). Second, our current model only captures one form of cognitive and physical tasks.…”

“…Although the current power grip manipulation involves less executive control as compared with precision grip (Ehrsson et al, 2000;Guillery et al, 2013Guillery et al, , 2017Kobayashi-Cuya et al, 2018), successful maintenance of the grip exertion may lead to an opportunity cost to the information control in the WM task at supra-capacity set sizes (Kurzban et al, 2013). Recent evidence showing that concurrent physical exertion could impact control-related task performance in visual search and visual WM tasks with distractors appears to be in line with this interpretation (Azer, Xie, Park, & Zhang, 2022;Park et al, 2021). In light of these findings, shared effort-related representations and processes across modalities may be rooted in the mechanisms involved in cognitive control (Kool & Botvinick, 2018;Shenhav et al, 2017).…”

“…Supporting this conjecture, we find that concurrent physical exertion impacts visual WM task performance only at a large supra-capacity set size, where the task demand on cognitive control is high. Yet, this prediction entails further investigation, such as testing the effect of concurrent physical exert on distractor inhibition in visual WM (Azer et al, 2022).…”