Influence of aging and visual feedback on the stability of hand grip control in elderly adults

The "Little Circles Test" (LCT): a dusted-off tool for assessing fine visuomotor function

BACKGROUND

The fine visuomotor function is commonly impaired in several neurological conditions. However, there is a scarcity of reliable neuropsychological tools to assess such a critical domain.

AIMS

The aim of this study is to explore the psychometric properties and provide normative data for the Visual-Motor Speed and Precision Test (VMSPT).

RESULTS

Our normative sample included 220 participants (130 females) aged 18-86 years (mean education = 15.24 years, SD = 3.98). Results showed that raw VMSPT scores were affected by higher age and lower education. No effect of sex or handedness was shown. Age- and education-based norms were provided. VMSPT exhibited weak-to-strong correlations with well-known neuropsychological tests, encompassing a wide range of cognitive domains of clinical relevance. By gradually intensifying the cognitive demands, the test becomes an indirect, performance-oriented measure of executive functioning. Finally, VMSPT seems proficient in capturing the speed-accuracy trade-off typically observed in the aging population.

CONCLUSIONS

This study proposes the initial standardization of a versatile, time-efficient, and cost-effective neuropsychological tool for assessing fine visuomotor coordination. We propose renaming the VMSPT as the more approachable "Little Circles Test" (LCT).

Analysis of Vibration Frequency and Direction for Facilitating Upper-Limb Muscle Activity

We aimed to determine the effect of vibration frequency and direction on upper-limb muscle activation using a handheld vibrator. We recruited 19 healthy participants who were instructed to hold a handheld vibrator in their dominant hand and maintain the elbow at 90° flexion, while vertical and horizontal vibrations were applied with frequencies of 15, 30, 45, and 60 Hz for 60 s each. Surface electromyography (EMG) measured the activities of the flexor digitorum superficialis (FDS), flexor carpi radialis (FCR), extensor carpi ulnaris (ECU), extensor carpi radialis (ECR), biceps, triceps, and deltoid anterior muscles. EMG changes were evaluated as the difference in muscle activity between vibration and no-vibration (0 Hz) conditions. Muscle activity was induced under vibration conditions in both vertical and horizontal (p < 0.05) directions. At 45 Hz, FDS and FCR activities increased during horizontal vibrations, compared with those during vertical vibrations. ECU activity significantly increased under 15-Hz vertical vibrations compared with that during horizontal vibrations. Vibrations from the handheld vibrator significantly induced upper-limb muscle activity. The maximum muscle activations for FDS, ECR, ECU, biceps, and triceps were induced by 45-Hz horizontal vibration. The 60-Hz vertical and 30-Hz horizontal vibrations facilitated maximum muscle activations for the FCR and deltoid anterior, respectively.

Validation of Vibration Exercises on Enhancing Muscle Strength and Upper Limb Functionality among Pre-Frail Community-Dwelling Older Adults

Pre-frail older adults require appropriate exercise to enhance muscle strength as well as upper limb functionality. We developed a handheld vibrator and evaluated its effectiveness in enhancing muscle strength compared to conventional exercises among pre-frail community-dwelling older adults. Thirty-one pre-frail older adults (aged 75.5 ± 5.1 years) were recruited and randomly allocated to a vibration group (VG) and control group (CG). The VG underwent 20 minutes of vibration (frequency: 30 Hz, amplitude: 5 mm, horizontal vibration) using a handheld vibrator as well as 40 minutes of conventional exercise. The CG received 60 minutes of conventional exercise only. The primary outcome was muscle strength assessment (kg), and the secondary outcome included activities of daily living and instrumental activities of daily living scores. The comparisons between the outcome measures revealed no significant differences at the baseline level. Muscle strength of the dominant (ß = 2.49, p = 0.002) and non-dominant (ß = 1.89, p = 0.02) wrist flexion, brachioradialis (ß = 3.8, p = 0.01), and biceps brachii (ß = 3.02, p = 0.02) in the dominant upper limbs was significantly increased among the VG. The vibration intervention can enhance muscle strength in the upper limbs among pre-frail older adults.

The impact of aging and reaching movements on grip stability control during manual precision tasks

Background

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. 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.

Methods

Fifty 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.

Results

For 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).

Conclusions

Aging 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.

A TRIZ-driven conceptualisation of finger grip enhancer designs for the elderly

Background: Elderly people with severe finger weakness may need assistive health technology interventions. Finger weakness impedes the elderly in executing activities of daily living such as unbuttoning shirts and opening clothes pegs. While studies have related finger weakness with ageing effects, there appears to be no research that uses an algorithmic problem-solving approach such as the theory of inventive problem-solving (TRIZ) to recommend finger grip assistive technologies that resolve the issue of finger weakness among the elderly. Using TRIZ, this study aims to conceptualise finger grip enhancer designs for elderly people. Methods: Several TRIZ tools such as the cause-and-effect chain (CEC) analysis, engineering contradiction, physical contradiction, and substance-field analysis are used to conceptualise solutions that assist elderly people in their day-to-day pinching activities. Results: Based on the segmentation principle, a finger assistant concept powered by a miniature linear actuator is recommended. Specific product development processes are used to further conceptualise the actuation system. The study concluded that the chosen concept should use a DC motor to actuate fingers through tendon cables triggered by a push start button. Conclusions: Finger pinch degradation worsens the quality of life of the elderly. A finger grip enhancer that assists in day-to-day activities may be an effective option for elderly people, not only for their physical but also their mental well-being in society.

Motor and Cognitive Performance in Patients with Liver Cirrhosis with Minimal Hepatic Encephalopathy

Minimal hepatic encephalopathy (MHE) is associated with mild cognitive impairment and frailty. This study aims to identify cognitive and motor differences in cirrhotic patients with and without MHE, and the correlations between motor signs and cognitive performance. Gait, balance, hand strength and motor speed performance were evaluated in 66 cirrhotic patients (38 without and 28 with MHE, according to the Psychometric Hepatic Encephalopathy Score (PHES). Cognitive performance was measured with the Mini-Mental State Examination, Verbal Fluency Test, Aprendizaje Verbal España-Complutense Test (TAVEC), Wechsler Adult Intelligence Scale III, Hamilton Depression and Anxiety Rating Scale and Functioning Assessment Short Test (FAST). MHE patients performed worse than patients without MHE in cognitive and autonomous functioning, learning and long-term memory, and verbal fluency. The same pattern was found in gait, center of pressure movement, variability of hand strength performance and hand motor speed. In MHE patients, high correlations were found between balance and FAST test, gait velocity and verbal skills, hand strength variability and anxiety and depression, and motor speed and FAST and TAVEC. MHE patients showed worse motor and cognitive performance than patients without MHE. MHE patients could have impaired movement control expressed as bradykinesia, and this reduced motor performance could correlate with cognitive performance.

Validating the Capability for Measuring Age-Related Changes in Grip-Force Strength Using a Digital Hand-Held Dynamometer in Healthy Young and Elderly Adults

Background

Grip-force performance can be affected by aging, and hand-grip weakness is associated with functional limitations of dasily living. However, using an appropriate digital hand-held dynamometer with continuous hand-grip force data collection shows age-related changes in the quality of hand-grip force control may provide more valuable information for clinical diagnoses rather than merely recording instantaneous maximal hand-grip force in frail elderly adults or people with a disability. Therefore, the purpose of this study was to indicate the construct validity of the digital MicroFET3 dynamometer with Jamar values for maximal grip-force assessments in elderly and young adults and confirmed age-related changes in the maximal and the quality of grip-force performance using the MicroFET3 dynamometer in elderly people.

Methods

Sixty-five healthy young (23.3 ± 4.5 years) and 50 elderly (69.5 ± 5.8 years) adults were recruited and asked to perform a validity test of the grip-force maximum voluntary contraction (MVC) using both the dominant and nondominant hands with a Jamar dynamometer and a MicroFET3 dynamometer.

Results

A strong correlation of maximal grip-force measurements was found between the MicroFET3 dynamometer and Jamar standard dynamometer for both hands in all participants (p < 0.05). Although, the results showed that a lower grip force was measured in both hands by the MicroFET3 dynamometer than with the Jamar dynamometer by 49.9%~57% (p < 0.05), but confidently conversion formulae were also developed to convert MicroFET3 dynamometer values to equivalent Jamar values for both hands. Both dynamometers indicated age-related declines in the maximum grip-force performance by 36.7%~44.3% (p < 0.05). We also found that the maximal hand-grip force values generated in both hand by the elderly adults were slower and more inconsistent than those of the young adults when using the MicroFET3 dynamometer.

Conclusions

This study demonstrated that the digital MicroFET3 dynamometer has good validity when used to measure the maximal grip force of both hands, and conversion formulae were also developed to convert MicroFET3 dynamometer force values to Jamar values in both hands. Comparing with the Jamar dynamometer for measuring grip force, the MicroFET3 dynamometer not only indicated age-related declines in the maximum grip-force performance but also showed slower and more inconsistent maximal hand-grip strength generation by the elderly.