Both hands at work: the effect of aging on upper-limb kinematics in a multi-step activity of daily living

Abstract

The kinematic performance of basic motor tasks shows a clear decrease with advancing age. This study examined if the rules known from such tasks can be generalized to activities of daily living. We examined the end-effector kinematics of 13 young and 13 elderly participants in the multi-step activity of daily living of tea-making. Furthermore, we analyzed bimanual behavior and hand dominance in the task using different conditions of execution. The elderly sample took substantially longer to complete the activity (almost 50%) with longer trajectories compared with the young sample. Models of multiple linear regression revealed that the longer trajectories prolonged the trial duration in both groups, and while movement speed influenced the trial duration of young participants, phases of inactivity negatively affected how long the activity took the elderly subjects. No differences were found regarding bimanual performance or hand dominance. We assume that in self-paced activities of daily living, the age-dependent differences in the kinematics are more likely to be based on the higher cognitive demands of the task rather than on pure motor capability. Furthermore, it seems that not all of the rules known from basic motor tasks can be generalized to activities of daily living.

Smoothness Metrics in Complex Movement Tasks

“…We compared the movements of the dominant hand of 8 healthy young adults (26.9a ± 2.1a) with the movements of the dominant hand of 8 healthy elderly participants (67.1a ± 7.1a). The ADL task was to unimanually prepare a cup of tea with milk and sugar ( 21 ). All participants were right handed and each participant executed the task once.…”

“…The experimental set-up was similar to the one in Gulde et al ( 21 ). Participants stood in front of a table with the following items placed on its surface in a semi-circular order from left to right: a container with room temperatured water, a milk carafe, a saucer for used tea-bags, an open container with tea-bags, an open container with sugar cubes, an open container with coffee powder (as a distractor item), and an empty kettle.…”

“…The used smoothness parameters were the spectral arc length ( 8 ), the (negative–see description) number of velocity peaks per meter ( 21 ), the speed metric ( 12 ) and the log dimensionless jerk ( 8 ). The spectral arc length is calculated from the arc length of the power spectrum of a Fourier transformation of the velocity signal ( 8 ).…”

“…The present classification bases on the differentiation between velocity peak, different kinds of jerk and spectral analysis metrics ( 12 , 17 , 19 ), whereas spectral analysis metrics follow the assumptiom that less smooth movements are more complex in terms of their frequency composition when approximating the original signal with a Fourier series [for an easy introduction to spectral analysis see ( 20 )]. Various velocity-based parameters were suggested: the number of velocity peaks ( 6 , 21 – 23 ), the normalized average speed ( 12 , 24 ), the relative level of activity ( 6 , 21 , 24 , 25 ), or the peak-based composition of the velocity profile ( 12 , 26 ). Acceleration-based parameters are examining the rate of change of movement acceleration and are usually forms of the jerk metric like the normalized jerk ( 27 , 28 ), the log dimensionless jerk ( 8 ), the normalized squared jerk ( 14 ), or the normalized mean jerk ( 12 ).…”

“…Further, we examined if the parameters are quantifying a general ability to produce smooth movements. ADL offer a way to examine behavior in the context of disease and aging in an ecological valid way and should therefore be considered in research and clinical assessment ( 6 , 10 , 11 , 21 , 32 ). This study tries to explore the behavior of different parameters in an empirical way in order to give suggestions and an outlook on future developments.…”