Abstract
BackgroundOperating an object by generating stable hand-grip force during static or dynamic posture control of the upper extremities simultaneously is an important daily activity. Older adults require different attentional resources during grip strength control and arm movements. However, the impact of aging and reaching movements on precise grip strength and stability control among older adults is not well understood. This study investigated the impact of aging and reaching movements on grip strength and stability control in both hands of the upper extremities.MethodsFifty healthy young adults (age: 28.8 ± 14.0 years) and 54 healthy older adults (73.6 ± 6.3 years) were recruited to perform isometric grip strength test at 20% maximal voluntary contraction as the target force during three manual precision tasks simultaneously: stationary task (without arm movements), forward-reach task, and backward-reach task. The average grip force (in kg) and coefficient of variation values (expressed as a percentage) during manual precision tasks were calculated to determine the quality of participants’ grip strength. The deviation error, absolute error, and force-stability index values were calculated to determine the strength control relative to the target force.ResultsFor both the young and older groups, the force-stability index values in both hands were significantly higher during forward- and backward-reaching movements than in the stationary condition (p < 0.05). The older group exhibited a significantly lower hand-grip strength and stability of strength control in both hands than the young group (p < 0.05).ConclusionsAging and reaching task performance reduced the grip strength of participants and increased the variations in strength control of both hands relative to the target force, indicating that older adults exhibit poor grip strength and stability control when performing arm-reaching movements. These findings may help clinical therapists in establishing objective indexes for poor grip-stability control screening and developing appropriate rehabilitation programs or health-promotion exercises that can improve grip strength and stability control in older people.
Highlights
Operating an object by generating stable hand-grip force during static or dynamic posture control of the upper extremities simultaneously is an important daily activity
Before grip-force stability control was assessed during the three manual precision tasks, the maximal voluntary contraction (MVC) test was conducted by asking all the participants to grasp the dynamometer with their maximum grip force; this task was performed for both hands
Mixed model ANOVA showed a significant interaction between group and manual precision tasks for grip force (F(5,618) = 18.016, p < 0.001, η2 = 0.120), coefficient of variation (CV) (F(5,618) = 31.817, p < 0.001, η2 = 0.198) values of musclestrength performance, deviation error (F(5,618) = 18.525, p < 0.001, η2 = 0.123), absolute error (F(5,618) = 6.100, p < 0.001, η2 = 0.390), and force-stability index (F(5,618) = 49.759, p < 0.001, η2 = 0.281) values of strengthstability control
Summary
Operating an object by generating stable hand-grip force during static or dynamic posture control of the upper extremities simultaneously is an important daily activity. Operating an object by generating stable hand-grip force during static or dynamic posture control of the upper extremities simultaneously is an important daily activity requiring different attentional resources during gripstrength control and arm movements. When the grip is steady, the attention would shift to the arm movement that may result in decreased gripstrength control During this manual precision task, applying a constant and stable grip strength using specific force and in relation to an object’s weight requires the cooperation of perception feedback, grip strength output, arm coordination control, and cognitive function (attention and working memory) [1]. There are scarce studies of this type focusing on older people
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