ABSTRACT
Age related declines in ability and function are well documented in the literature. Adults over the age of 65 have reduced strength and range of motion (ROM) as compared to the younger population. Aging therefore can lead to difficulties completing tasks of daily living. Older adults cope with excessive physical demands by modifying the way they perform a task or by modifying the environment. Difference in behaviors between older and younger adult have been identified for seated reach tasks. These differences in behavior may illustrate how older adults cope with tasks that are not optimally designed for their abilities. This pilot study investigates the differences in the postural strategies adopted for a low forward reach task between older and younger adults to further the understanding of coping strategies adopted by individuals with reduced ability.
Maximum unrestricted low forward reach was assessed for 18 older adults and 25 younger adults. Maximum low forward reach was defined as the maximum reach distance from the foot to the center of a can (0.5 kg) placed onto a shelf at knee height. Posture was not restricted; however, participants had to keep their feet together and could not kneel when performing the task. Anthropometry and active ROM data were recoded for each individual. Interaction strategy or postural joint angles including knee flexion angle, back flexion angle and shoulder flexion angle were coded using still images for the maximum low forward reaching task.
There were significant differences between young and older adults in the maximum low forward reach distance. After controlling for stature and gender, there were significant differences in the multivariate effect of interaction strategy adopted between groups. Univariate analysis indicated differences in back flexion 98and shoulder flexion angles between groups. Results indicate that shoulder flexion ROM had a greater influence on reach as compared to back flexion ROM.
The findings of the study suggested that older adults were more likely to stand with their feet straighter and not flex their back or shoulder as much as younger adults. This could be due limitations in balance, stability and strength in the lower limbs. The differences in behavior might suggest that different design affordances may be required to aid the different groups in completing forward reaching tasks. Further research is needed to understand why individuals with limited ability adopt different interaction strategies. In addition, the results demonstrate that it is important to consider differences in interaction strategies employed by user groups when evaluating human task performance and in design of products and environments.
