The influence of mechanical vibration on local and central balance control

What are the temporal and physical characteristics of locally applied vibration that modulate balance in older adults? - A systematic review of the literature

BACKGROUND

Compromised balance is known to contribute to falls, which are associated with increased morbidity and mortality for older adults. Evidence suggests that the application of local vibration to the lower limbs of older adults has the potential to modulate balance.

RESEARCH QUESTION

To identify the temporal and mechanical parameters of vibration applied locally to the lower limbs of older adults that modulate measures of balance, and to define the short- and long-term effects of vibration on balance in this population.

METHODS

The PRISMA 2020 guidelines were used to conduct a systematic search including the PUBMED, EMBASE, and Scopus databases to identify peer-reviewed literature where vibration was applied to the lower limbs of older adults to modulate balance. Data was extracted using a study-specific data extraction form and risk of bias assessed. Where possible, effect sizes were calculated.

RESULTS

Of 7777 records screened, ten randomised controlled trials and 43 prospective laboratory-based studies met the inclusion criteria. Vibration frequencies ranged from 1 to 272 Hz, most studies (n=41) used ≤100 Hz. Amplitude ranged from 0.2 to 3.0 mm, most studies (n=28) used ≤1 mm. Effects of short-term vibration (applied for seconds to hours) were measured during and/or immediately after application. Short-term suprathreshold perceived muscle/tendon vibration had a 'large' destabilising effect size on balance in healthy older adults, but little or no effect on older fallers. Short-term subthreshold vibration to the soles of the feet had a 'small' stabilising effect size. Suprathreshold muscle, tendon or sole vibration applied for 10-30 min over days to weeks improved balance measures, but most (8 of 10) had increased risk of bias.

SIGNIFICANCE

The heterogeneity of methodology, populations, and vibration and balance parameters precluded conclusions about the relative effects of lower limb vibration in older adults. However, these results suggest that the application of local vibration to the lower limbs of older adults can modulate balance in the short- and long-term.

Effects of percussion massage therapy, dynamic stretching, and static stretching on physical performance and balance

BACKGROUND

Percussion massage therapy is a popular approach in sport medicine for physical therapists, but few researchers have investigated the comparison with other intervention methods.

OBJECTIVE

This study aimed to examine the comparison of the effects of dynamic stretching, static stretching and percussive massage therapy on balance and physical performance in individuals.

METHODS

The participants who were 18-25 years of age, able to perform performance tests, did not have any orthopedic surgery, did not have problems during running and sudden turning, and did not have a professional sports history were included in the study. Participants were assigned randomly to three groups as dynamic stretching (DS) (n= 16), static stretching (SS) (n= 16) and percussive massage therapy (PMT) (n= 16) groups. Horizontal jumping test, T drill test and balance measurements on a single leg with open and closed eyes of all participants were recorded before and after applications.

RESULTS

When the values of the pre and post-treatment of all groups in the study were compared, significant improvements were observed in the t-test, horizontal jumping test and right/left foot balance with eyes open in DS group (p< 0.05). Significant improvements were observed in all values in the PMT group (p< 0.05). In the comparison of the differences between the groups, PMT group values were more significant than the SS group in all parameters.

CONCLUSION

Percussive massage therapy would be an alternative that can be used to increase the performance and balance of individuals before exercise.

The Effects of Vibratory and Acoustic Stimulations on Postural Control in Healthy People: A Systematic Review

Research on human posture and balance control has grown in recent years, leading to continued advances in their understanding. The ability to maintain balance is attributed to the interplay of the visual, vestibular, and somatosensory systems, although an important role is also played by the auditory system. The lack or deficit in any of these systems leads to a reduced stability that may be counterbalanced by the integration of all the remaining sensory information. Auditory and vibratory stimulation have been found to be useful to enhance balance alongside daily activities either in healthy or pathological subjects; nevertheless, while widely investigated, the literature relating to these approaches is still fragmented. This review aims at addressing this by collecting, organising, and discussing all the literature to date on the effects of the various acoustic and vibratory stimulation techniques available on static upright posture in healthy subjects. In addition, this review intends to provide a solid and comprehensive starting point for all the researchers interested in these research areas. A systematic search of the literature was performed and a total of 33 articles (24 on vibratory stimulation and 9 on acoustic stimulation) were included in our analysis. For all articles, several elements were highlighted including: the study sample, the characteristics of the stimulations, the recording instruments, the experimental protocols, and outcomes. Overall, both stimulations analysed were found to have a positive effect on balance but more research is needed to align those alternative approaches to the traditional ones.

Potential Usefulness of Tracking Head Movement via a Wearable Device for Equilibrium Function Testing at Home

Many studies have reported the use of wearable devices to acquire biological data for the diagnosis and treatment of various diseases. Balance dysfunction, however, is difficult to evaluate in real time because the equilibrium function is conventionally examined using a stabilometer installed on the ground. Here, we used a wearable accelerometer that measures head motion to evaluate balance and examined whether it performs comparably to a conventional stabilometer. We constructed a simplified physical head-feet model that simultaneously records “head” motion measured using an attached wearable accelerometer and center-of-gravity motion at the “feet”, which is measured using an attached stabilometer. Total trajectory length (r = 0.818, p -false discovery rate [FDR] = 0.004) and outer peripheral area (r = 0.691, p -FDR = 0.026) values measured using the wearable device and stabilometer were significantly positively correlated. Root mean square area values were not significantly correlated with wearable device stabilometry but were comparable. These results indicate that wearable, widely available, non-medical devices may be used to assess balance outside the hospital setting, and new approaches for testing balance function should be considered.

Ability of Wearable Accelerometers-Based Measures to Assess the Stability of Working Postures

With the rapid development and widespread application of wearable inertial sensors in the field of human motion capture, the low-cost and non-invasive accelerometer (ACC) based measures have been widely used for working postural stability assessment. This study systematically investigated the abilities of ACC-based measures to assess the stability of working postures in terms of the ability to detect the effects of work-related factors and the ability to classify stable and unstable working postures. Thirty young males participated in this study and performed twenty-four load-holding tasks (six working postures × two standing surfaces × two holding loads), and forty-three ACC-based measures were derived from the ACC data obtained by using a 17 inertial sensors-based motion capture system. ANOVAs, t-tests and machine learning (ML) methods were adopted to study the factors’ effects detection ability and the postural stability classification ability. The results show that almost all forty-three ACC-based measures could (p < 0.05) detect the main effects of Working Posture and Load Carriage, and their interaction effects. However, most of them failed in (p ≥ 0.05) detecting Standing Surface’s main or interaction effects. Five measures could detect both main and interaction effects of all the three factors, which are recommended for working postural stability assessment. The performance in postural stability classification based on ML was also good, and the feature set exerted a greater influence on the classification accuracy than sensor configuration (i.e., sensor placement locations). The results show that the pelvis and lower legs are recommended locations overall, in which the pelvis is the first choice. The findings of this study have proved that wearable ACC-based measures could assess the stability of working postures, including the work-related factors’ effects detection ability and stable-unstable working postures classification ability. However, researchers should pay more attention to the measure selection, sensors placement, feature selection and extraction in practical applications.

Electromyographic responses to unexpected Achilles tendon vibration-induced perturbations during standing in young and older people

This study aimed to investigate age-related differences in electromyographic (EMG) responses to unexpected Achilles tendon vibration (ATV) perturbations while standing blindfold. ATV with variable and random duration (12-15 s) and rest periods (20-24 s) was applied on 18 young and 16 older volunteers. The anterior/posterior center of pressure (CoP) and the soleus (SOL) and tibialis anterior (TA) EMG were analyzed for 1 s before and 8 s after the ATV onset and offset. ATV induced a posterior shift of CoP in both groups, with more pronounced shift in the older group. During ATV onset, the older group demonstrated less SOL and more TA EMG increase compared to the young group. During the first 0.5 s of ATV offset, SOL EMG was decreased in both age groups, while TA showed a burst of EMG activity that was greater in the older group. No difference in the latencies of EMG peaks or valleys was observed between the groups. It is concluded that ATV induces greater posterior CoP shift in older adults, and they adopt a recovery strategy, characterized by a decreased SOL activation and an increased TA activation. These differences are possibly attributed to the increased fear of falling, decreased limits of stability and reduced capacity of older people to reweight their sensory inflow when proprioception is distorted.

Isolated post-traumatic astereognosis: a case-based review

INTRODUCTION

Astereognosis is the tactile inability to recognize objects placed in the palms by touch with the eyes closed or blind-folded in the presence of intact primary sensory modalities. Stereognosis is usually considered a function of the contralateral sensory cerebral cortex. However, lesions of several anatomic areas and pathologic entities have been reported to be associated with astereognosis. Only two previous reports linked traumatic injury to isolated astereognosis: following surgical evacuation of traumatic parietal extradural hematoma and following bullet injury in the neck in 1992 and 1919, respectively.

METHODS AND RESULTS

All the pertinent literature was analyzed, focusing on the relevant definitions, clinical spectra, pathoanatomical processes, assessment, management, and outcomes of astereognosis. Also, an illustrative case was presented. The case highlights isolated post-traumatic left hand astereognosis in a 17-year-old boy following a blunt trauma to the head which resulted in a non-hemorrhagic contusion of the right post-central gyrus.

CONCLUSIONS

Post-traumatic isolated astereognosis is a rare and probably underreported sequel of traumatic brain injury. Neurosurgeons need to be more sensitive to the assessment and detection of subtle stereognostic deficits in general and in trauma patients in particular. Other anatomical areas, in addition to the contralateral post-central gyrus, may be considered in the pathogenesis of astereognosis with the involvement of the dorsal column medial lemniscus tract such as the brainstem, foramen magnum, and the cervical spinal cord. To the best of our knowledge, this rare case report is considered the second report on astereognosis following head trauma, and the third report on astereognosis following trauma in general.

The Focal Mechanical Vibration for Balance Improvement in Elderly - A Systematic Review

Background

Aging has been associated with the progressive depletion of lean mass, reductions in muscle strength and the coordination of the lower extremities, accompanied by decreased gait assurance and balance control. Also, less balance control favors falling which is the leading cause of injury among the elderly. The aim of this systematic review is to identify and evaluate existing evidence regarding the use of focused vibration (FV) to improve balance and reduce the risk of falling during the rehabilitation of elderly populations.

Methods

The PICO question is what are the effects of focal/segmental/local vibration training on the assessment of balance and the risk of falls among the elderly population? A thorough literature review was conducted between May 1, 2009, and June 30, 2019, for studies in English, randomized clinical trials, including crossover and prospective design studies with assessing balance and the risk of falls in elderly populations (age > 60 years).

Results

Eight articles (N = 8) satisfied the inclusion criteria and were considered, of which 6 are RTC, one cross-sectional study and one clinical study, for a total of 635 participants. A total of 6 different vibration devices were used, each of which was associated with different FV frequency and amplitude characteristics and different treatment protocols.

Conclusion

In conclusion, FV can be effective in decreasing the risk of falls and improving the assessment of balance, but more evidence is necessary considering the limits of the studies; however, it does look an important promise during rehabilitative treatment.

Performance and Characteristics of Wearable Sensor Systems Discriminating and Classifying Older Adults According to Fall Risk: A Systematic Review

Sensor-based fall risk assessment (SFRA) utilizes wearable sensors for monitoring individuals’ motions in fall risk assessment tasks. Previous SFRA reviews recommend methodological improvements to better support the use of SFRA in clinical practice. This systematic review aimed to investigate the existing evidence of SFRA (discriminative capability, classification performance) and methodological factors (study design, samples, sensor features, and model validation) contributing to the risk of bias. The review was conducted according to recommended guidelines and 33 of 389 screened records were eligible for inclusion. Evidence of SFRA was identified: several sensor features and three classification models differed significantly between groups with different fall risk (mostly fallers/non-fallers). Moreover, classification performance corresponding the AUCs of at least 0.74 and/or accuracies of at least 84% were obtained from sensor features in six studies and from classification models in seven studies. Specificity was at least as high as sensitivity among studies reporting both values. Insufficient use of prospective design, small sample size, low in-sample inclusion of participants with elevated fall risk, high amounts and low degree of consensus in used features, and limited use of recommended model validation methods were identified in the included studies. Hence, future SFRA research should further reduce risk of bias by continuously improving methodology.

Effects of white Gaussian noise on dynamic balance in healthy young adults

It has been known that short-time auditory stimulation can contribute to the improvement of the balancing ability of the human body. The present study aims to explore the effects of white Gaussian noise (WGN) of different intensities and frequencies on dynamic balance performance in healthy young adults. A total of 20 healthy young participants were asked to stand at a dynamic balance force platform, which swung along the x-axis with an amplitude of ± 4° and frequency of 1 Hz. Their center of pressure (COP) trajectories were recorded when they were stimulated by WGN of different intensities (block 1) and different frequencies (block 2). A traditional method and detrended fluctuation analysis (DFA) were used for data preprocessing. The authors found that only with 75–85 dB WGN, the COP parameters improved. WGN frequency did not affect the dynamic balance performance of all the participants. The DFA results indicated stimulation with 75 dB WGN enhanced the short-term index and reduced the crossover point. Stimulation with 500 Hz and 2500 Hz WGN significantly enhanced the short-term index. These results suggest that 75 dB WGN and 500 Hz and 2500 Hz WGN improved the participants’ dynamic balance performance. The results of this study indicate that a certain intensity of WGN is indispensable to achieve a remarkable improvement in dynamic balance. The DFA results suggest that WGN only affected the short-term persistence, indicating the potential of WGN being considered as an adjuvant therapy in low-speed rehabilitation training.

The effect of vibratory stimulation on the timed-up-and-go mobility test: a pilot study for sensory-related fall risk assessment

Effects of localized lower-extremity vibration on postural balance have been reported. The purpose of the current study was to investigate the effect of low-frequency vibration of calf muscles on the instrumented Timed-Up-and-Go (iTUG) test among older adults. Older adults were recruited and classified to low (n=10, age=72.9±2.8 years) and high fall risk (n=10, age=83.6±9.6) using STEADI. Vibratory system (30Hz or 40Hz), was positioned on calves along with wearable motion sensors. Participants performed the iTUG test three times, under conditions of no-vibration, 30Hz, and 40Hz vibration. Percentage differences in duration of iTUG components were calculated comparing vibration vs no-vibration conditions. Significant between-group differences were observed in iTUG (p=0.03); high fall risk participants showed reduction in the duration of turning (-10 % with 30Hz; p=0.15 and -15 % with 40Hz; p=0.03) and turning and sitting (-18 % with 30Hz; p=0.02 and -10 % with 40Hz; p=0.08). However, vibration increased turning (+18 % with 30Hz; p=0.20 and +27 % with 40Hz; p=0.12) and turning and sitting duration (+27 % with 30Hz; p=0.11 and +47 % with 40Hz; p=0.12) in low fall risk participants. Findings suggest that lower-extremity vibration affects dynamic balance; however, the level of this influence may differ between low and high fall risk older adults, which can potentially be used for assessing aging-related sensory deficits.

Influence of age on the frequency characteristics of the soleus muscle response to Achilles tendon vibration during standing

KEY POINTS

Proprioceptive sensory information from the ankle joint is critical for the control of upright posture and balance. We examined the influence of age (n = 54 healthy adults, 20-82 years old) on lower limb muscle responses to proprioceptive perturbations evoked by Achilles tendon vibration during standing. The frequency bandwidth of the muscle response became narrower, and the gain (the muscle response relative to the stimulus) and scaling (increases in response amplitude with increases in stimulus amplitude) decreased with age. Mechanics of the muscle-tendon unit (mechanical admittance) did not differ with age during standing, and thus probably did not mediate the age-related changes observed in soleus muscle responses to vibration. These findings add to our understanding of how altered proprioceptive responses may contribute to impaired mobility and falls with ageing.

ABSTRACT

Proprioceptive information from the ankle joint plays an important role in the control of upright posture and balance. Ageing influences many components of the sensorimotor system, which leads to poor mobility and falls. However, little is known about the influence of age on the characteristics of short latency muscle responses to proprioceptive stimuli during standing across frequencies that are encoded by muscle spindles. We examined the frequency characteristics of the soleus muscle response to noisy (10-115 Hz) Achilles tendon vibration during standing in 54 healthy adults across a broad age range (20-82 years). The results showed the frequency bandwidth of the soleus response (vibration-electromyography coherence) became progressively narrower with ageing. Coherence was significantly lower in middle-aged relative to young adults between ∼7-11 and 28-62 Hz, lower in older relative to middle-aged adults between ∼30-50 Hz and lower in older relative to young adults between ∼7-64 Hz. Muscle response gain was similar between age groups at low frequencies, although gain was lower in older relative to young adults between ∼28-54 Hz. Across the age range, the response amplitude (peak-to-peak cross-covariance) and the scaling of the response with stimulus amplitude were both negatively correlated with age. Muscle-tendon mechanics (admittance) did not differ with age, suggesting this did not mediate differences in soleus responses. Our findings suggest there is a progressive change in the soleus response to proprioceptive stimuli with ageing during standing, which could contribute to poorer mobility and falls.

Relationship between postural stability and fall risk in elderly people with lumbar spondylosis during local vibratory stimulation for proprioception: a retrospective study

Purpose: Reduced proprioception affects fall risks in elderly people with lumbar spondylosis. The decrease in proprioception in the trunk or lower legs may contribute to a decline in postural stability. We aimed to investigate the association between proprioceptive postural stability and fall risks in elderly individuals with lumbar spondylosis.Materials and Methods: In this retrospective study, the centre-of-pressure displacement was determined in elderly individuals with lumbar spondylosis during upright stance while standing on a Wii Balance Board with their eyes closed (fall-risk group, n = 55; non-fall-risk group, n = 60). Vibratory stimulations at 30 Hz were applied to the lumbar multifidus and gastrocnemius to evaluate the relative contributions of proprioceptive signals used in postural control (relative proprioceptive weighting ratio).Results: Compared with the non-fall-risk group, the fall-risk group displayed a high relative proprioceptive weighting ratio (p = 0.024). Relative proprioceptive weighting ratio (odds ratio, 1.1; 95% confidence interval: 1.004-1.109) was independently associated with fall risks after adjusting for confounding factors. Among variables related to fall risk, the relative proprioceptive weighting ratio was a significant factor (p < 0.035).Conclusion: The fall-risk group of elderly individuals with lumbar spondylosis was dependent on the ankle strategy. The fall risk in elderly people with lumbar spondylosis could be due to over-dependence on the input from muscle spindles in the gastrocnemius.

Can motor function uncertainty and local instability within upper-extremity dual-tasking predict amnestic mild cognitive impairment and early-stage Alzheimer's disease?

In this study, we examined the uncertainty and local instability of motor function for cognitive impairment screening using a previously validated upper-extremity function (UEF). This approach was established based upon the fact that elders with an impaired executive function have trouble in the simultaneous execution of a motor and a cognitive task (dual-tasking). Older adults aged 65 years and older were recruited and stratified into 1) cognitive normal (CN), 2) amnestic MCI of the Alzheimer's type (aMCI), and 3) early-stage Alzheimer's Disease (AD). Participants performed normal-paced repetitive elbow flexion without counting and while counting backward by ones and threes. The influence of cognitive task on motor function was measured using uncertainty (measured by Shannon entropy), and local instability (measured by the largest Lyapunov exponent) of elbow flexion and compared between cognitive groups using ANOVAs, while adjusting for age, sex, and BMI. We developed logistic ordinal regression models for predicting cognitive groups based on these nonlinear measures. A total of 81 participants were recruited, including 35 CN (age = 83.8 ± 6.9), 30 aMCI (age = 83.9 ± 6.9), and 16 early AD (age = 83.2 ± 6.6). Uncertainty of motor function demonstrated the strongest associations with cognitive impairment, with an effect size of 0.52, 0.88, and 0.51 for CN vs. aMCI, CN vs. AD, and aMCI vs. AD comparisons, respectively. Ordinal logistic models predicted cognitive impairment (aMCI and AD combined) with a sensitivity and specificity of 0.82. The findings accentuate the potential of employing nonlinear dynamical features of motor functions during dual-tasking, especially uncertainty, in detecting cognitive impairment.

The Effects of Baduanjin Qigong on Postural Stability, Proprioception, and Symptoms of Patients With Knee Osteoarthritis: A Randomized Controlled Trial

Background: Knee osteoarthritis is a common disease affecting a large number of old individuals worldwide. This study aimed to explore the effects of Baduanjin Qigong in patients with knee osteoarthritis. Methods: Fifty participants with knee osteoarthritis were randomly assigned to either an experimental group (n = 25) or a control group (n = 25). Participants in the experimental group received Baduanjin Qigong training for 12 weeks, with three sessions per week lasting 40 min per session. Participants in the control group did not receive any additional physical training. All of participants completed outcome (proprioception, postural stability, and functional ability) assessments at three time points (baseline, Week 8, 12). Results: Proprioception and Western Ontario and McMaster Universities Osteoarthritis Index function were statistically improved at eighth and 12th week of the intervention in the Baduanjin Qigong group (p < 0.05), while the control group did not have any significant changes. For postural stability at the anterior-posterior direction with eyes closed, Baduanjin Qigong group showed significant improvement compared to controls after the 12 weeks of intervention (p < 0.05). Conclusions: Regular Baduanjin Qigong practice helped the improvement of knee joint proprioception and postural stability, and reduction of pain, stiffness, and functional impairments of old adults with knee osteoarthritis. Well-designed randomized controlled trials with long-term assessment are needed. The trial was registered in Chinese Clinical Trial Registry (ChiCTR-IOR-16010042). URL: http://www.chictr.org.cn/hvshowproject.aspx?id=10550.

Aftereffects of prolonged Achilles tendon vibration on postural control are reduced in older adults

AIM

To assess the change in the contribution of proprioceptive signal from leg muscles in postural control with ageing.

METHODS

Fifteen young (~23 yr) and fifteen older adults (~68 yr) participated in Experiment 1, which consisted of recording the mean position of the centre of pressure (CoP), CoP path length, CoP velocity, and the amplitude of the Hoffmann (H) reflex and maximal M wave (M_MAX) in the soleus muscle during upright standing, before and after 1 h of bilateral Achilles tendon vibration applied in seated posture. Eight young (~24 yr) and eight older adults (~67 yr) participated in Experiment 2 consisting of recording H-reflex and M_MAX in seated posture before and after the 1-h vibration procedure used in Experiment 1.

RESULTS

Immediately after the 1-h vibration, the mean CoP position shifted forward in both groups (p < 0.05), with a greater magnitude of change (% pre-vibration) in young [mean(SD); 74(41)%] than older adults [44(40)%; p < 0.05]. The CoP path length and velocity only increased in young adults after vibration (p < 0.05). The H-reflex amplitude decreased only in young adults after vibration [before: 35(12); after: 16(13)% M_max, p < 0.05] during upright standing (Experiment 1), whereas it decreased similarly (p > 0.05) in young [before: 47(12)% M_max; after: 28(17)% M_max] and older adults [before: 34(13)% M_max; after: 21(14)% M_max] in seated posture (Experiment 2).

CONCLUSION

Prolonged Achilles tendon vibrations lead to lesser postural perturbation in older than in young adults, supporting the assumption of a decreased reliance on leg muscle proprioception in postural control with ageing.

Wearable Inertial Sensors to Assess Standing Balance: A Systematic Review

Wearable sensors are de facto revolutionizing the assessment of standing balance. The aim of this work is to review the state-of-the-art literature that adopts this new posturographic paradigm, i.e., to analyse human postural sway through inertial sensors directly worn on the subject body. After a systematic search on PubMed and Scopus databases, two raters evaluated the quality of 73 full-text articles, selecting 47 high-quality contributions. A good inter-rater reliability was obtained (Cohen's kappa = 0.79). This selection of papers was used to summarize the available knowledge on the types of sensors used and their positioning, the data acquisition protocols and the main applications in this field (e.g., "active aging", biofeedback-based rehabilitation for fall prevention, and the management of Parkinson's disease and other balance-related pathologies), as well as the most adopted outcome measures. A critical discussion on the validation of wearable systems against gold standards is also presented.

Age-related changes in leg proprioception: implications for postural control

In addition to being a prerequisite for many activities of daily living, the ability to maintain steady upright standing is a relevant model to study sensorimotor integrative function. Upright standing requires managing multimodal sensory inputs to produce finely tuned motor output that can be adjusted to accommodate changes in standing conditions and environment. The sensory information used for postural control mainly arises from the vestibular system of the inner ear, vision, and proprioception. Proprioception (sense of body position and movement) encompasses signals from mechanoreceptors (proprioceptors) located in muscles, tendons, and joint capsules. There is general agreement that proprioception signals from leg muscles provide the primary source of information for postural control. This is because of their exquisite sensitivity to detect body sway during unperturbed upright standing that mainly results from variations in leg muscle length induced by rotations around the ankle joint. However, aging is associated with alterations of muscle spindles and their neural pathways, which induce a decrease in the sensitivity, acuity, and integration of the proprioceptive signal. These alterations promote changes in postural control that reduce its efficiency and thereby may have deleterious consequences for the functional independence of an individual. This narrative review provides an overview of how aging alters the proprioceptive signal from the legs and presents compelling evidence that these changes modify the neural control of upright standing.

The association between cognition and dual-tasking among older adults: the effect of motor function type and cognition task difficulty

Background

Dual-task actions challenge cognitive processing. The usefulness of objective methods based on dual-task actions to identify the cognitive status of older adults has been previously demonstrated. However, the properties of select motor and cognitive tasks are still debatable. We investigated the effect of cognitive task difficulty and motor task type (walking versus an upper-extremity function [UEF]) in identifying cognitive impairment in older adults.

Methods

Older adults (≥65 years) were recruited, and cognitive ability was measured using the Montreal Cognitive Assessment (MoCA). Participants performed repetitive elbow flexion under three conditions: 1) at maximum pace alone (Single-task); and 2) while counting backward by ones (Dual-task 1); and 3) threes (Dual-task 2). Similar single- and dual-task gait were performed at normal speed. Three-dimensional kinematics were measured for both motor functions using wearable sensors.

Results

One-hundred older adults participated in this study. Based on MoCA score <20, 21 (21%) of the participants were considered cognitively impaired (mean age =86±10 and 85±5 for cognitively impaired and intact participants, respectively). Within ANOVA models adjusted with demographic information, UEF dual-task parameters, including speed and range-of-motion variability were significantly higher by 52% on average, among cognitively impaired participant (p<0.01). Logistic models with these UEF parameters plus age predicted cognitive status with sensitivity, specificity, and area under curve (AUC) of 71%, 81% and 0.77 for Dual-task 1. The corresponding values for UEF Dual-task 2 were 91%, 73% and 0.81, respectively. ANOVA results were non-significant for gait parameters within both dual-task conditions (p>0.26).

Conclusion

This study demonstrated that counting backward by threes within a UEF dual-task experiment was a pertinent and challenging enough task to detect cognitive impairment in older adults. Additionally, UEF was superior to gait as the motor task component of the dual-task. The UEF dual-task could be applied as a quick memory screen in a clinical setting.

Self-evaluation by community older adults on the applicability of the healthy beat acupunch exercise program

Objectives To evaluate the applicability of the Healthy Beat Acupunch (HBA) exercise program for older adults at community care centers and to explore their perceived impacts and suggestions for program protocol after six months of HBA exercises. Design & setting This prospective and descriptive study recruited 113 older adults from four community care centers. Intervention The HBA exercises were conducted 3 times a week, 40 min per session, for six months. Main outcome measures The program evaluation focused on four criteria: simplicity, safety, suitability, and helpfulness of the three phases of the HBA program using a 10-point ladder scale. The semi-structured interviews were focused on the participants' exercise experiences, perceived impacts on their health, and suggestions for the HBA program protocol. Results The average scores of the four criteria in each phase of the program ranged between 9.59 and 9.98 points. Participants reported an increase in their limb flexibility (n = 31) and that they were more relaxed (n = 26) and more energetic (n = 26) after engaging in the HBA exercises. Most of the participants suggested that the HBA program should be offered three times a week, 40 min per session, with 30 people in a group, and led by instructors who were professional, hardworking, easygoing, and enthusiastic, regardless of gender and age. Conclusions The HBA program was rated at a high level of simplicity, safety, suitability, and helpfulness by community older adults, which indicated that the program was considered as appropriate and applicable for the older population.

Postural Strategy in Elderly, Middle-Aged, and Young People during Local Vibratory Stimulation for Proprioceptive Inputs

Proprioceptive input may greatly affect postural stability. However, the proprioceptive postural strategy in elderly, middle-aged, and young people has not been investigated sufficiently. Hence, in this study, we aimed to investigate differences in proprioceptive postural strategies of elderly, middle-aged, and young people. The center of pressure displacement was determined in 23 elderly, 23 middle-aged, and 23 young people during upright stance on a balance board with their eyes closed. Vibratory stimulations at 30, 60, and 240 Hz were applied to the lumbar multifidus (LM) and gastrocnemius (GS) muscles to evaluate the contributions of different proprioceptive signals used in balance control. Compared with middle-aged and young people, elderly people showed a high dependence on postural control of the GS at 30 Hz (p-values: Young and elderly: 0.033; middle-aged and elderly: 0.001). Moreover, compared with young people, elderly people were more dependent on postural control of the LM at 240 Hz (p = 0.016). There were no significant differences with respect to the GS at 60 and 240 Hz, and with respect to the LM at 30 and 60 Hz between the elderly, young, and middle-aged people. Thus, the postural control strategy of elderly people depends on the GS at 30 Hz.

Upper-extremity function prospectively predicts adverse discharge and all-cause COPD readmissions: a pilot study

Background

Frailty can inform management approaches for individuals with COPD. However, inpatient measures of frailty are seldom employed because they are time-consuming or inapplicable for bed-bound patients. We investigated the feasibility and potential of an innovative sensor-based upper-extremity function (UEF) test for frailty assessment in predicting adverse outcomes.

Methods

Hospitalized patients with COPD-related exacerbations (aged ≥55 years) were recruited and performed the UEF test within 24 hours of admission. UEF parameters were obtained and fed into our previously developed frailty model to calculate frailty status (non-frail, pre-frail, and frail) and frailty score (0: extreme resilience to 1: extreme frailty). In-hospital (length of stay) and post-discharge (discharge disposition, 30-day exacerbation with treatment, and all-cause 30-day readmission) outcomes were collected. Associations between UEF frailty and outcomes were investigated using ANOVA and logistic models adjusted for demographic data.

Results

In total, 42 patients were recruited. All participants were able to perform the UEF test. Based on UEF, participants were stratified into three groups of non-frail (n=6, frailty score =0.18±0.09), pre-frail (n=14, frailty score =0.45±0.09), and frail (n=22, frailty score =0.78±0.11). Both frailty status and frailty score were significantly associated with unfavorable discharge disposition (P<0.005) and all-cause 30-day readmission (P<0.05). On the other hand, UEF frailty measures were associated with neither hospital length of stay (P>0.5) nor 30-day exacerbation with treatment (P>0.70). Age was only significantly associated with unfavorable discharge disposition (P=0.048).

Conclusion

In agreement with previous work, the current findings underline the importance of measuring frailty for risk-stratification of COPD patients. The UEF was feasible and easily performed among all hospitalized COPD patients. In this study, we have shown that, using our quick and objective frailty measures, COPD patients can be prospectively risk-stratified in terms of unfavorable discharge disposition and all-cause 30-day readmissions.

Sharif-Human movement instrumentation system (SHARIF-HMIS): Development and validation

The interest in wearable systems among the biomedical engineering and clinical community continues to escalate as technical refinements enhance their potential use for both indoor and outdoor applications. For example, an important wearable technology known as a microelectromechanical system (MEMS) is demonstrating promising applications in the area of biomedical engineering. Accordingly, this study was designed to investigate the Sharif-Human Movement Instrumentation System (SHARIF-HMIS), consisting of inertial measurement units (IMUs), stretchable clothing, and a data logger-all of which can be used outside the controlled environment of a laboratory, thus enhancing its overall utility. This system is lightweight, portable, able to be deliver data for almost 10 h, and features a new data-fusion algorithm using the Kalman filter with an adaptive approach. In specific terms, the data from the system's gyroscope, accelerometer, and magnetometer sensors can be combined to estimate total-body orientation; additionally, the noise level of these sensors can be changed to accommodate faster motions as well as magnetic disturbances. These variations can be incorporated within the extended Kalman filter by changing the parameters of the filter adaptively. In specific terms, the system's interface was developed to acquire data from eighteen IMUs located on the body to collect kinematic data associated with human motion. Meanwhile, a validation test involving one subject performing different shoulder motions was designed to compare data captured by SHARIF-HMIS and the VICON motion-capture system. This validation test demonstrated correlation values of >0.9. Results also confirmed that the output accuracy of the new system's sensor was <0.55, 1.5 and 3.5° for roll, pitch, and yaw directions, respectively. In summary, SHARIF-HMIS successfully collected kinematic data for specific human movements, which has promising implications for a range of sporting, biomedical, and healthcare-related applications.