Evaluation of postural stability based on a force plate and inertial sensor during static balance measurements

Assessing standing balance with MOTI: a validation study

OBJECTIVES

This study aimed to determine the validity and reliability of a new device called MOTI for measuring balance by comparing its performance that with of the gold-standard force platform.

METHODS

The study involved collecting data from both devices in dual- and single-leg standing positions with eyes open and closed and using statistical measures to compare their performance.

RESULTS

The results showed that MOTI can accurately measure balance during dual-leg standing tasks but has poor to moderate performance during single-leg standing tasks. However, it could detect small changes in postural sway caused by a reduced base of support and/or visual feedback. The study also found that the test-retest reliability was poor to moderate for both devices.

CONCLUSIONS

These findings suggest that MOTI has potential as a reliable tool for measuring balance during certain tasks, but further research is needed to improve its performance during single-leg standing. This study provides valuable insights into the validity and reliability of MOTI for measuring balance and highlights the need for further investigation.

Postural behaviour in people with multiple sclerosis: A complexity paradox

BACKGROUND

Balance deficits are a major concern for people with multiple sclerosis (pwMS). Measuring complexity of motor behaviour can offer an insight into MS-related changes in adaptability of the balance control system when dealing with increasingly complex tasks.

QUESTION

Does postural behaviour complexity differ between pwMS at early stages of the disease and healthy controls (HC)? Does postural behaviour complexity change across increasingly complex tasks?

METHODS

Forty-eight pwMS and 24 HC performed four increasingly complex postural tasks with eyes open (EO), eyes closed (EC), on firm (FS) and compliant surface (CS). Lumbar and sternum sensors recorded 3D acceleration, from which complexity index (CI) was calculated using multiscale sample entropy (MSE) in the frontal and sagittal planes.

RESULTS

We found that only the complexity index in both planes during the eyes closed on compliant surface (EC-CS) task was significantly lower in pwMS compared to HC. We also found that complexity in pwMS was significantly lower during EC-CS compared to the other three tasks when using both lumbar and sternum sensors.

SIGNIFICANCE

Increasing the complexity of postural tasks reduces the complexity of postural behaviour in pwMS. This paradox may reflect reduced adaptability of the sensorimotor integration processes at early stages of MS. CI can provide a different perspective on balance deficits and could potentially be a more sensitive biomarker of MS progression and an early indicator of balance deficit.

The Convergent Validity of the SWAY Balance Application to Assess Postural Stability in Military Cadets Recovering from Concussion

Background

Concussions are often accompanied by balance disturbances. Clinically accurate evaluation systems are often expensive, large, and inaccessible to most clinicians. The Sway Balance Mobile Application (SWAY) is an accessible method to quantify balance changes.

Purpose

To determine the known groups and convergent validity of the SWAY to assess balance after a concussion.

Study Design

Case-Control Study.

Methods

Twenty participants with acute concussion and twenty controls were recruited. At initial, one-week, and final return to activity (RTA) evaluations, all participants completed the Sports Concussion Assessment Tool (SCAT-5), and balance control measured by SWAY mBESS and NeuroCom Balance Master Sensory Organization Test (SOT). Mixed model ANOVAs were used to detect differences in SWAY mBESS and NeuroCom SOT scores with time (initial, one-week, final RTA) as the within-subjects factor and group (concussed, healthy) as the between-subjects factor. Spearman's Rho correlations explored the associations between NeuroCom SOT scores, SWAY scores, SCAT-5 symptom scores, and time in days to final RTA.

Results

The sampled population was predominantly male and age (20 ± 1), and BMI differences were insignificant between groups. The SWAY did not detect differences between healthy and concussed participants and did not detect change over time [F(2,40) = .114, p = 0.89; F(2,40)= .276, p =0.60]. When assessing the relationship between the SWAY and the SOT, no correlation was found at any time point (r = -0.317 to -0.062, p > 0.05). Time to RTA demonstrated a moderate correlation with both SCAT-5 symptom severity score (r = .693, p < 0.01) and SCAT-5 total symptom score (r = .611, p < 0.01) at the one-week follow-up.

Conclusion

The SWAY mBESS does not appear to be a valid balance assessment for the concussed patient. The SWAY mBESS in patients with concussion failed to demonstrate convergent validity and did not demonstrate an ability to validate known groups. When assessing the time to final RTA, the one-week post-initial assessment SCAT-5 symptom severity and total scores may help determine the length of recovery in this population.

Level of Evidence

Level 3.

Feasibility of Acquiring Neuroimaging Data from Adults with Acquired Brain Injuries before and after a Yoga Intervention

BACKGROUND

To date, no one has prospectively evaluated yoga intervention-induced changes in brain structure or function in adults with acquired brain injuries (ABI). Thus, this study was conducted to test the feasibility of acquiring neuroimaging data from adults with ABI before and after a yoga intervention.

METHODS

This was a single-arm intervention feasibility study that included 12 adults with chronic (i.e., greater than 6 months post-injury) ABI and self-reported limitations in balance. Neuroimaging data were acquired before and after yoga. The yoga intervention was completed once per week for eight weeks. Feasibility objectives and benchmarks were established a priori.

RESULTS

Most feasibility objectives and benchmarks were achieved. The goal of recruiting 12 participants was successfully achieved, and 75% of participants were retained throughout the study (goal of 80%). All imaging feasibility benchmarks were met; rs-fMRI and fNIRS data were acquired safely, data were of acceptable quality, and data pre-processing procedures were successful. Additionally, improvements were detected in balance after yoga, as group-level balance was significantly better post-yoga compared to pre-yoga, p = 0.043.

CONCLUSIONS

These findings indicate it is feasible to acquire neuroimaging data from adults with ABI before and after a yoga intervention. Thus, future prospective studies are warranted.

External mechanical perturbations challenge postural stability in dogs

This study aimed to explore the effect of external mechanical perturbations on postural stability (PS) in dogs using the body center of pressure (COP). Thirteen sound adult dogs were included in this study. PS was tested during quiet standing on a pressure measurement plate. The conditions included a standard standing measurement and external mechanical perturbations conducted using six settings on a motorized training platform with different intensities of speed and amplitude. Measurement conditions were compared using linear mixed-effects models, followed by multiple comparisons using Sidak's alpha correction procedure. Compared with the standing measurement, external mechanical perturbations resulted in a significant increase in almost all COP parameters, indicating a challenge for the PS. Furthermore, an increase in amplitude had a greater effect than an increase in speed, whereas the combination of the highest intensities of amplitude and speed was not well tolerated by the dogs. The mediolateral COP displacement was significantly greater than the craniocaudal COP displacement during standing measurement and conditions with a small amplitude, whereas no significant difference was observed during settings with an increased amplitude. To the best of our knowledge, this is the first study to demonstrate the effects of a balance training device in dogs. Therefore, the intensity of the training programs on motorized platforms or similar devices can be controlled by the wobbling amplitude of the platform.

What Is the Role of Sustained Visual Attention in the Maintenance of Postural Control in Young Adults?

Dual tasks requiring sustained visual attention and upright stance are common, yet their impact on standing balance is not well understood. We investigated the role of visual attention in the maintenance of postural control, using the multiple-object tracking (MOT) task. Healthy young adults (n = 12) performed the MOT task at three object movement speeds while seated or standing. MOT performance was assessed using tracking capacity (k). Metrics calculated to assess mediolateral (ML) and anterior-posterior (AP) postural control included: maximum difference between CoM and CoP position (CoM-CoP Max), root mean square distance for center of pressure and center of mass position (CoP and CoM RMS distance), and correlation between CoM and CoP time series signals (CoM/CoP correlation). As predicted, k decreased significantly as object movement speed increased for both standing and seated conditions. Object movement speed also significantly affected AP CoM-CoP Max in seated conditions (p = .021) and AP CoM/CoP correlation for standing conditions (p = .002). The results demonstrate utility of the MOT task in understanding the role of visual attention in postural control, even though healthy young adults were able to compensate for the addition of a sustained visual attention task, with minimal deficits to postural control.

Sensory Interaction and Balancing Ability Evaluation of the Elderly Using a Simplified Force Plate System

The Wii balance board (WBB) is a simplified force plate system used to evaluate the balancing ability of the elderly via a sensory interaction task to confirm a significant standing balance index. The accuracy of this system has been verified in previous studies. In this study, an instrumented and modified clinical test of sensory interaction on balance (i-mCTSIB) was performed on 84 elderly subjects, and the variables for center of pressure (CoP) were calculated using WBB for each task condition. The results indicate that the visual condition has a significant effect on the sway proprioceptive sensory variables with a foam condition as their complexity increases. In addition, the correlation between the variable and Berg Balance Scale was not confirmed since CTSIB is a sensory interaction on balance ability. Therefore, WBB can be used to evaluate balancing ability based on sensory interactions consisting of the surface condition.

Quantification of Gait Stability During Incline and Decline Walking: The Responses of Required Coefficient of Friction and Dynamic Postural Index

This study aims to investigate the gait stability response during incline and decline walking for various surface inclination angles in terms of the required coefficient of friction (RCOF), postural stability index (PSI), and center of pressure (COP)-center of mass (COM) distance. A customized platform with different surface inclinations (0°, 5°, 7.5°, and 10°) was designed. Twenty-three male volunteers participated by walking on an inclined platform for each inclination. The process was then repeated for declined platform as well. Qualysis motion capture system was used to capture and collect the trajectories motion of ten reflective markers that attached to the subjects before being exported to a visual three-dimensional (3D) software and executed in Matlab to obtain the RCOF, PSI, as well as dynamic PSI (DPSI) and COP-COM distance parameters. According to the result for incline walking, during initial contact, the RCOF was not affected to inclination. However, it was affected during peak ground reaction force (GRF) starting at 7.5° towards 10° for both walking conditions. The most affected PSI was found at anterior-posterior PSI (APSI) even as low as 5° inclination during both incline and decline walking. On the other hand, DPSI was not affected during both walking conditions. Furthermore, COP-COM distance was most affected during decline walking in anterior-posterior direction. The findings of this research indicate that in order to decrease the risk of falling and manage the inclination demand, a suitable walking strategy and improved safety measures should be applied during slope walking, particularly for decline and anterior-posterior orientations. This study also provides additional understanding on the best incline walking technique for secure and practical incline locomotion.

High-Performance pH Sensor Electrodes Based on a Hexagonal Pt Nanoparticle Array-Coated Nanoporous Alumina Membrane

Porous anodic alumina membranes coated with Pt nanoparticles (PAAM/Pt) have been employed as pH sensor electrodes for H⁺ ion detection. The PAAM was designed using a two-step anodization process. Pt nanoparticles were then sputtered onto the membrane at different deposition times. The membrane's morphological, chemical, and optical characteristics were carefully assessed following the fabrication stage using a variety of analytical techniques. The potential of the PAAM/Pt sensor electrode was investigated by measuring the potential using a simple potentiometric method. The effects of depositing Pt nanoparticles for 3-7 min on sensor electrode sensitivity were examined. The optimal potentiometric Nernstian response slope for the PAAM/Pt sensor electrode with 5 min Pt sputter coating is 56.31 mV/decade in the pH range of 3.0 to 10 at 293 K. Additionally, the PAAM/Pt sensor electrode's stability and selectivity in various ions solutions were examined. The sensor electrode had a lifetime of more than six weeks and was kept in a normal air environment.

A Comparison among Different Strategies to Detect Potential Unstable Behaviors in Postural Sway

Assistive Technology helps to assess the daily living and safety of frail people, with particular regards to the detection and prevention of falls. In this paper, a comparison is provided among different strategies to analyze postural sway, with the aim of detecting unstable postural status in standing condition as precursors of potential falls. Three approaches are considered: (i) a time-based features threshold algorithm, (ii) a time-based features Neuro-Fuzzy inference system, and (iii) a Neuro-Fuzzy inference fed by Discrete-Wavelet-Transform-based features. The analysis was performed across a wide dataset and exploited performance indexes aimed at assessing the accuracy and the reliability of predictions provided by the above-mentioned strategies. The results obtained demonstrate valuable performances of the three considered strategies in correctly distinguishing among stable and unstable postural status. However, the analysis of robustness against noisy data highlights better performance of Neuro-Fuzzy inference systems with respect to the threshold-based algorithm.

Potential of Whole-Body Vibration in Parkinson’s Disease: A Systematic Review and Meta-Analysis of Human and Animal Studies

Simple Summary

Exercise has shown to have a positive impact on both motor and non-motor functions in Parkinson’s Disease patients. However, particularly in later stages of the disease, reduced cognitive function and motor capacity may lead to an inability to stay physically active. Therefore, alternative strategies for patients with Parkinson’s Disease are necessary to minimize burden for patients, their families and public health care. Whole-Body Vibration could be such an alternative. Whole-Body Vibration is an exercise or treatment method in which subjects are exposed to a mechanical vibration while sitting, standing or exercising on a vibrating platform. Whole-Body Vibration is currently used for physiotherapy, sports and rehabilitation purposes. Whole-Body Vibration treatment is interesting because it affects both the body and brain. The potential of Whole-Body Vibration for, specifically, Parkinson’s Disease patients should be clarified for further application. For this purpose, we conducted an extensive systematic review of the articles investigating the effects of Whole-Body Vibrations (1) on animals and humans with Parkinson’s Disease and (2) on neuropathological Parkinson’s Disease mechanisms. The results show some potential of Whole-Body Vibration for Parkinson’s Disease patients. The recommendations provided by this review can be used by researchers and rehabilitative practitioners implementing Whole-Body Vibration as a treatment for Parkinson’s Disease patients.

Abstract

(1) Background: When the severity of Parkinson’s Disease (PD) increases, patients often have difficulties in performing exercises. Whole-Body Vibration (WBV) may be a suitable alternative. This systematic review aims to clarify if WBV shows potential as rehabilitative therapy for PD patients. (2) Methods: We searched several databases for controlled trials investigating the effects of WBV (1) on PD populations and (2) PD neuropathological mechanisms. We included both human and animal studies and performed meta-analyses. (3) Results: The studies on PD populations (14 studies) show an overall significant, but small, effect in favor of WBV (Hedges’ g = 0.28), for which the effects on stability (Hedges’ g = 0.39) and balance (Hedges’ g = 0.30) are the most prominent. The studies on the neuropathological mechanisms (18 studies) show WBV effects on neuroinflammation (Hedges’ g = –1.12) and several specific WBV effects on neurotransmitter systems, growth factors, neurogenesis, synaptic plasticity and oxidative stress. (4) Conclusions: The effects of WBV on human PD patients remains inconclusive. Nevertheless, WBV protocols with sufficient duration (≥3 weeks), session frequency (≥3 sessions/week) and vibration frequency (≥20 Hz) show potential as a treatment method, especially for motor function. The potential of WBV for PD patients is confirmed by the effects on the neuropathological mechanisms in mostly non-PD populations. We recommend high-quality future studies on both PD patients and PD mouse models to optimize WBV protocols and to examine the neuropathological mechanisms in PD populations.

Application of Machine Learning to Predict Trajectory of the Center of Pressure (COP) Path of Postural Sway Using a Triaxial Inertial Sensor

Postural sway indicates controlling stability in response to standing balance perturbations and determines risk of falling. In order to assess balance and postural sway, costly laboratory equipment is required, making it impractical for clinical settings. The study aimed to develop a triaxial inertial sensor and apply machine learning (ML) algorithms for predicting trajectory of the center of pressure (COP) path of postural sway. Fifty-three healthy adults, with a mean age of 46 years, participated. The inertial sensor prototype was investigated for its concurrent validity relative to the COP path length obtained from the force platform measurement. Then, ML was applied to predict the COP path by using sensor-sway metrics as the input. The results of the study revealed that all variables from the sensor prototype demonstrated high concurrent validity against the COP path from the force platform measurement (ρ > 0.75; $p<0.001$ ). The agreement between sway metrics, derived from the sensor and ML algorithms, illustrated good to excellent agreement (ICC; 0.89–0.95) between COP paths from the sensor metrics, with respect to the force plate measurement. This study demonstrated that the inertial sensor, in comparison to the standard tool, would be an option for balance assessment since it is of low-cost, conveniently portable, and comparable to the accuracy of standard force platform measurement.

Scoring of Human Body-Balance Ability on Wobble Board Based on the Geometric Solution

Many studies have reported that the human body-balance ability was essential in the early detection and self-management of chronic diseases. However, devices to measure balance, such as motion capture and force plates, are expensive and require a particular space for installation as well as specialized knowledge for analysis. Therefore, this study aimed to propose and verify a new algorithm to score the human body-balance ability on the wobble board (HBBAWB), based on a geometric solution using a cheap and portable device. Although the center of gravity (COG), the projected point of the center of mass (COM) on the fixed ground, has been used as the index for the balance ability, generally, it was not proper to use the COG under the condition of no fixed environment. The reason was that the COG index did not include the information on the slope for the wobble. Thus, this study defined the new index as the perpendicular-projection point (PPP), which was the projected point of the COM on the tilted plane. The proposed geometric solution utilized the relationship among three points, the PPP, the COM, and the middle point between the two feet, via linear regression. The experimental results found that the geometric solution, which utilized the relationship between the three angles of the equivalent model, enabled us to score the HBBAWB.

Static Balance Digital Endpoints with Mon4t: Smartphone Sensors vs. Force Plate

Static balance tests are conducted in various clinics for diagnosis and treatment adjustment. As a result of population aging, the accessibility of these tests should be increased, in the clinic, and for remote patient examination. A number of publications have already conducted static balance evaluations using the sensors embedded in a smartphone. This study focuses on the applicability of using smartphone-based balance assessment on a large scale while considering ease of use, safety, and reliability. The Mon4t^® app was used to acquire the postural motion using different smartphone devices, different smartphone locations, and various standing postures. The signals derived from the app were compared to the center of pressure displacement derived from a force plate. The results showed moderate to high agreement between the two methods, particularly at the tandem stance (0.69 ≤ r ≤ 0.91). Preliminary data collection was conducted on three healthy participants, followed by 50 additional healthy volunteers, aged 65+. The results demonstrated that the Mon4t app can serve as an accessible and inexpensive static balance assessment tool, both in clinical settings and for remote patient monitoring, which is key for enabling telehealth.

Towards defining biomarkers to evaluate concussions using virtual reality and a moving platform (BioVRSea)

Current diagnosis of concussion relies on self-reported symptoms and medical records rather than objective biomarkers. This work uses a novel measurement setup called BioVRSea to quantify concussion status. The paradigm is based on brain and muscle signals (EEG, EMG), heart rate and center of pressure (CoP) measurements during a postural control task triggered by a moving platform and a virtual reality environment. Measurements were performed on 54 professional athletes who self-reported their history of concussion or non-concussion. Both groups completed a concussion symptom scale (SCAT5) before the measurement. We analyzed biosignals and CoP parameters before and after the platform movements, to compare the net response of individual postural control. The results showed that BioVRSea discriminated between the concussion and non-concussion groups. Particularly, EEG power spectral density in delta and theta bands showed significant changes in the concussion group and right soleus median frequency from the EMG signal differentiated concussed individuals with balance problems from the other groups. Anterior–posterior CoP frequency-based parameters discriminated concussed individuals with balance problems. Finally, we used machine learning to classify concussion and non-concussion, demonstrating that combining SCAT5 and BioVRSea parameters gives an accuracy up to 95.5%. This study is a step towards quantitative assessment of concussion.

Efficacy of unloader knee orthosis and lateral wedge insole on static balance in medial knee osteoarthritis

Background

Medial knee osteoarthritis can contribute to pain and stiffness, interfere with balance and limit functional activities of daily living. Unloader knee orthosis or lateral wedged insoles are current conservative approaches used to treat these conditions. The aim of this study was to identify and compare the effects of them on the balance parameters.

Methods

66 subjects with mild to moderate medial knee osteoarthritis were randomly assigned to wear unloader knee brace or full-length 6° lateral wedge insole. Primary outcome balance parameters were stability %, path length and average velocity of center of pressure and mobility score which were investigated by HUMAC® Balance and Tilt system. Secondary outcome measures were knee function score using Knee Injury and Osteoarthritis Outcome Score scale. Assessment was performed at baseline and six months post orthotic intervention period.

Findings

Both orthoses improved all parameters compared to the baseline condition (p < 0.05). Unloader knee orthosis showed a significant improvement in all balance parameters compared to lateral wedged insoles (p < 0.001) except mobility scores (p = 0.527). Except activities of daily living (p = 0.752) and sports and recreational activities (p = 0.437), unloader knee orthosis had a greater effect on the pain (p = 0.002) and symptoms (p < 0.001) sub scales than lateral wedged insoles. However, quality of life sub-scale scores for insoles were more effective than the knee orthosis.

Interpretation

Unloader knee orthosis improved balance and knee function scores more than lateral wedged insole, though both orthoses produced significantly improved results compared to baseline assessment.

Random Forest for Automatic Feature Importance Estimation and Selection for Explainable Postural Stability of a Multi-Factor Clinical Test

Falling is a common incident that affects the health of elder adults worldwide. Postural instability is one of the major contributors to this problem. In this study, we propose a supplementary method for measuring postural stability that reduces doctor intervention. We used simple clinical tests, including the timed-up and go test (TUG), short form berg balance scale (SFBBS), and short portable mental status questionnaire (SPMSQ) to measure different factors related to postural stability that have been found to increase the risk of falling. We attached an inertial sensor to the lower back of a group of elderly subjects while they performed the TUG test, providing us with a tri-axial acceleration signal, which we used to extract a set of features, including multi-scale entropy (MSE), permutation entropy (PE), and statistical features. Using the score for each clinical test, we classified our participants into fallers or non-fallers in order to (1) compare the features calculated from the inertial sensor data, and (2) compare the screening capabilities of the multifactor clinical test against each individual test. We use random forest to select features and classify subjects across all scenarios. The results show that the combination of MSE and statistic features overall provide the best classification results. Meanwhile, PE is not an important feature in any scenario in our study. In addition, a t-test shows that the multifactor test of TUG and BBS is a better classifier of subjects in this study.

Concurrent Validity of Inertially Sensed Measures during Voluntary Body Sway in Silence and while Exposed to a Rhythmic Acoustic Stimulus: A Pilot Study

Introduction

The effect of rhythmic acoustic stimuli on body sway is of increasing interest due to their positive contribution when training or restoring the control of movement. Inertial sensors show promise as a portable, easier, and more affordable method compared to the force plate "gold standard" concerning the evaluation of postural sway. This study examined the concurrent validity of inertially sensed measures of voluntary body sway against those obtained with a force plate, in silence and while exposed to a rhythmic acoustic stimulus.

Methods

Temporal (sway duration and variability) and spatial (trajectory length, variability, range, velocity, and area) body sway variables were extracted using an inertial sensor (at L5) in synchronization with a force plate, during anteroposterior body sway in silence and while exposed to a rhythmic acoustic stimulus (n = 18 young women; two 70-s trials in each condition). Statistics included bivariate correlations between the inertially sensed and the force plate measures, separately, in silence and with a rhythmic acoustic stimulus, as well as for the effect of the rhythmic acoustic stimulus (percentage difference from silence) (p ≤ 0.05, SPSS v25.0).

Results

The inertially sensed measures demonstrated good-to-excellent concurrent validity for all temporal and almost all spatial variables, both in silence and with rhythmic acoustic stimulus (r > 0.75, p = 0.000), as well as for the rhythmic acoustic-stimulus effect (r > 0.75, p ≤ 0.05).

Conclusion

The inertially sensed measures of the voluntary anteroposterior body sway demonstrated an overall good-to-excellent concurrent validity against those obtained with the force plate "gold standard," both in the silence and the rhythmic acoustic stimulus conditions, as well as for the rhythmic acoustic-stimulus effect. The findings of this pilot study allow the recommendation of inertial sensing for the evaluation of postural control alterations when exposed to rhythmic acoustic stimuli, a condition of increasing interest due to the positive contribution of such stimuli when training or restoring the control of movement.

Chen B. A Data-Driven Approach to Predict Fatigue in Exercise Based on Motion Data from Wearable Sensors or Force Plate

Fatigue increases the risk of injury during sports training and rehabilitation. Early detection of fatigue during exercises would help adapt the training in order to prevent over-training and injury. This study lays the foundation for a data-driven model to automatically predict the onset of fatigue and quantify consequent fatigue changes using a force plate (FP) or inertial measurement units (IMUs). The force plate and body-worn IMUs were used to capture movements associated with exercises (squats, high knee jacks, and corkscrew toe-touch) to estimate participant-specific fatigue levels in a continuous fashion using random forest (RF) regression and convolutional neural network (CNN) based regression models. Analysis of unseen data showed high correlation (up to 89%, 93%, and 94% for the squat, jack, and corkscrew exercises, respectively) between the predicted fatigue levels and self-reported fatigue levels. Predictions using force plate data achieved similar performance as those with IMU data; the best results in both cases were achieved with a convolutional neural network. The displacement of the center of pressure (COP) was found to be correlated with fatigue compared to other commonly used features of the force plate. Bland-Altman analysis also confirmed that the predicted fatigue levels were close to the true values. These results contribute to the field of human motion recognition by proposing a deep neural network model that can detect fairly small changes of motion data in a continuous process and quantify the movement. Based on the successful findings with three different exercises, the general nature of the methodology is potentially applicable to a variety of other forms of exercises, thereby contributing to the future adaptation of exercise programs and prevention of over-training and injury as a result of excessive fatigue.

Effects of Combined Balance and Strength Training on Measures of Balance and Muscle Strength in Older Women With a History of Falls

OBJECTIVE

We investigated the effects of combined balance and strength training on measures of balance and muscle strength in older women with a history of falls.

METHODS

Twenty-seven older women aged 70.4 ± 4.1 years (age range: 65 to 75 years) were randomly allocated to either an intervention (IG, n = 12) or an active control (CG, n = 15) group. The IG completed 8 weeks combined balance and strength training program with three sessions per week including visual biofeedback using force plates. The CG received physical therapy and gait training at a rehabilitation center. Training volumes were similar between the groups. Pre and post training, tests were applied for the assessment of muscle strength (weight-bearing squat [WBS] by measuring the percentage of body mass borne by each leg at different knee flexions [0°, 30°, 60°, and 90°], sit-to-stand test [STS]), and balance. Balance tests used the modified clinical test of sensory interaction (mCTSIB) with eyes closed (EC) and opened (EO), on stable (firm) and unstable (foam) surfaces as well as spatial parameters of gait such as step width and length (cm) and walking speed (cm/s).

RESULTS

Significant group × time interactions were found for different degrees of knee flexion during WBS (0.0001 < p < 0.013, 0.441 < d < 0.762). Post hoc tests revealed significant pre-to-post improvements for both legs and for all degrees of flexion (0.0001 < p < 0.002, 0.697 < d < 1.875) for IG compared to CG. Significant group × time interactions were found for firm EO, foam EO, firm EC, and foam EC (0.006 < p < 0.029; 0.302 < d < 0.518). Post hoc tests showed significant pre-to-post improvements for both legs and for all degrees of oscillations (0.0001 < p < 0.004, 0.753 < d < 2.097) for IG compared to CG. This study indicates that combined balance and strength training improved percentage distribution of body weight between legs at different conditions of knee flexion (0°, 30°, 60°, and 90°) and also decreased the sway oscillation on a firm surface with eyes closed, and on foam surface (with eyes opened or closed) in the IG.

CONCLUSION

The higher positive effects of training seen in standing balance tests, compared with dynamic tests, suggests that balance training exercises including lateral, forward, and backward exercises improved static balance to a greater extent in older women.

Smartphone-Based Evaluation of Postural Stability in Parkinson’s Disease Patients During Quiet Stance

Background: Postural instability is one of the most troublesome motor symptoms of Parkinson’s Disease (PD). It impairs patients’ quality of life and results in high risk of falls. The aim of this study is to provide a reliable tool for the automated assessment of postural instability. Methods: Data acquisition was performed on 42 PD patients and 7 young healthy subjects. They were asked to keep a quiet stance position for at least 30 s while wearing a waist-mounted smartphone. A total number of 414 features was extracted from both time and frequency domain, selected based on Pearson’s correlation, and fed to an optimized Support Vector Machine. Results: The implemented model was able to differentiate patients with mild postural instability from those with severe postural instability and from healthy controls, with 100% accuracy. Conclusion: This study demonstrated the feasibility of using inertial sensors embedded in commercial smartphones and proposed a simple protocol for accurate postural instability scoring. This tool can be used for early detection of PD motor signs, disease follow-up and fall prevention.

E-Textiles for Healthy Ageing

The ageing population has grown quickly in the last half century with increased longevity and declining birth rate. This presents challenges to health services and the wider society. This review paper considers different aspects (e.g., physical, mental, and social well-being) of healthy ageing and how health devices can help people to monitor health conditions, treat diseases and promote social interactions. Existing technologies for addressing non-physical (e.g., Alzheimer's, loneliness) and physical (e.g., stroke, bedsores, and fall) related challenges are presented together with the drivers and constraints of using e-textiles for these applications. E-textiles provide a platform that enables unobtrusive and ubiquitous deployment of sensors and actuators for healthy ageing applications. However, constraints remain on battery, integration, data accuracy, manufacturing, durability, ethics/privacy issues, and regulations. These challenges can only effectively be met by interdisciplinary teams sharing expertise and methods, and involving end users and other key stakeholders at an early stage in the research.