The Impact of Age and Physical Activity Level on Manual Aiming Performance

Abstract

Older adults traditionally adapt their discrete aiming movements, thereby traveling a larger proportion of the movement under closed-loop control. As the beneficial impact of a physically active lifestyle in older age has been described for several aspects of motor control, we compared the aiming performance of young controls to active and sedentary older adults. To additionally determine the contribution of visual feedback, aiming movements were executed with and without saccades. Results showed only sedentary older adults adopted the typical movement changes, highlighting the impact of a physically active lifestyle on manual aiming in older age. In an attempt to reveal the mechanism underlying the movement changes, evidence for an age-related decline in force control was found, which in turn resulted in an adapted aiming strategy. Finally, prohibiting saccades did not affect older adults’ performance to a greater extent, suggesting they do not rely more on visual feedback than young controls.

The multiple process model of goal-directed reaching revisited

“…A strategy of undershooting downward movements to a greater extent than other movements appears to be even more pronounced in older adults (Bennett et al, 2012). This exaggerated 'play-it-safe' strategy in older adults is consistent with other findings in the literature which show that older adults often sacrifice movement speed to reduce final endpoint error and minimize energy expenditure (Ketcham et al, 2002; Goal-Directed Reaching 9 Poletti et al, 2015;Pratt et al, 1994;Van Halewyck et al, 2014, 2015a, 2015bWelsh et al, 2007).…”

Why is the explicit component of motor adaptation limited in elderly adults?

“…brain atrophy, altered brain connectivity) (Guttmann et al, 1998;Raz et al, 2005;Davis et al, 2012). Age-related movement deficits are already present during simple point-to-point reaching movements, occurring as increased spatial and temporal movement variability and movement slowing (Darling et al, 1989;Yan et al, 1998;Ketcham et al, 2002;Van Halewyck et al, 2015). Apart from the movement parameters that are altered with aging, controlling movement might also impose increased cognitive demand on older…”

The influence of early aging on eye movements during motor simulation

“…As the size of the medium target was not vastly different to either the large or small target, the focus of the strategy could have been either speed or accuracy. Indeed, contemporary research (Van Halewyck et al 2014 ) has reported no age related differences in primary saccade amplitude when tasks that only differ by an ID of 1 bit are used. The medium target was therefore excluded from the analysis to remove any confound related to task strategy.…”