Isometric handgrip exercise speeds working memory responses in younger and older adults.

Abstract

Physiological arousal affects attention and memory, sometimes enhancing and other times impairing what we attend to and remember. In the present study, we investigated how changes in physiological arousalinduced through short bursts of isometric handgrip exercise-affected subsequent working memory performance. A sample of 57 younger (ages 18-29) and 56 older (ages 65-85) participants performed blocks of isometric handgrip exercise in which they periodically squeezed a therapy ball, alternating with blocks of an auditory working memory task. We found that, compared with those in a control group, participants who performed isometric handgrip had faster reaction times on the working memory task. Handgrip-speeded responses were observed for both younger and older participants, across working memory loads. Analysis of multimodal physiological responses indicated that physiological arousal increased during handgrip. Our findings suggest that performing short bouts of isometric handgrip exercise can improve processing speed, and they offer testable possibilities for the mechanism underlying handgrip's effects on performance. The potential for acute isometric exercise to temporarily improve processing speed may be of particular relevance for older adults who show declines in processing speed and working memory. Public Significance StatementThis study suggests that isometric exercise is a strategy to temporarily improve working memory performance in younger and older adults. These findings may be of particular relevance for older adults who show declines in processing speed and working memory.

The emotion paradox in the aging body and brain

“…When cognitive demands increase, the vmPFC should change its target autonomic state to be more noradrenergic than during rest. Indeed, pupil dilation increases linearly with working memory load, both in older and younger adults, 246 consistent with a rapid increase in LC activity in response to higher cognitive demands. Thus, during cognitively demanding situations, older adults' vmPFC may no longer attempt to suppress noradrenergic and sympathetic activity, eliminating the brain's proparasympathetic state.…”

Higher handgrip strength is linked to higher salience ventral attention functional network segregation in older adults

“…In particular, performance of an isometric handgrip exercise concurrently elicits spontaneous pupil diameter fluctuations 53 , 54 , which have been shown to track vigilance 55 , 56 . Vigilance, or tonic alertness, describes the intrinsic capacity to sustain attention for a period of time 57 and is part of the alerting system, one of three systems (the other two being orienting and executive control) proposed by Posner and Petersen to be involved in attention 46 , 58 .…”

“…In a study examining handgrip strength associations with 30 behavioural outcomes in >40,000 participants from the UK Biobank, processing speed (measured as reaction time) was found to show the most robust association with handgrip strength 64 , which the authors partly attributed to the strong dependence of the reaction time task on motor speed and dexterity (both closely associated with the muscular function of the hands) 65 . Several studies have also demonstrated that short bouts of isometric handgrip exercises can temporarily improve reaction times in an auditory oddball task 54 , an auditory n-back task 53 and a Go/No-Go task 66 , underscoring the link between handgrip strength and processing speed, as well as raising the possibility of training handgrip strength to improve processing speed. As for the salience/ventral attention network, lower salience/ventral attention network functional connectivity has been found to relate to age-related decreases in visual processing speed (i.e., the rate of visual information uptake) 67 .…”