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PARK16 is associated with PD in the Malaysian population

Gopalai AA, Ahmad-Annuar A, Li HH, Zhao Y, Lim SY, Tan AH, et al.

Am J Med Genet B Neuropsychiatr Genet, 2016 09;171(6):839-47.
PMID: 27174169 DOI: 10.1002/ajmg.b.32454

PARK16 was identified as a risk factor for Parkinson's disease in a Japanese cohort; however, subsequent studies in the other populations including the Chinese, European, Caucasian, and Chilean have shown a protective role instead. To investigate this locus in our Malaysian cohort, 1,144 individuals were screened for five SNPs in the PARK16 locus and logistic regression analysis showed that the A allele of the rs947211 SNP reduced the risk of developing PD via a recessive model (Odds ratio 0.57, P-value 0.0003). Pooled analysis with other Asian studies showed that A allele of the rs947211 SNP decreased the risk of developing PD via a recessive model (Odds ratio 0.71, P-value 0.0001). In addition, when meta-analysis was performed with other Asian population, three SNPs (rs823128, rs823156, and rs11240572) reduced risk of developing PD via a dominant model. © 2016 Wiley Periodicals, Inc.
Lack of association between the LRRK2 A419V variant and Asian Parkinson's disease

Gopalai AA, Lim SY, Aziz ZA, Lim SK, Tan LP, Chong YB, et al.

Ann Acad Med Singap, 2013 May;42(5):237-40.
PMID: 23771111

INTRODUCTION: The G2385R and R1628P LRRK2 gene variants have been associated with an increased risk of Parkinson's disease (PD) in the Asian population. Recently, a new LRRK2 gene variant, A419V, was reported to be a third risk variant for PD in Asian patients. Our objective was to investigate this finding in our cohort of Asian subjects.
MATERIALS AND METHODS: Eight hundred and twenty-eight subjects (404 PD patients, and 424 age and gender-matched control subjects without neurological disorders) were recruited. Genotyping was done by Taqman® allelic discrimination assay on an Applied Biosystems 7500 Fast Real-Time PCR machine.
RESULTS: The heterozygous A419V genotype was found in only 1 patient with PD, compared to 3 in the control group (0.4% vs 1.3%), giving an odds ratio of 0.35 (95% confidence interval (CI), 0.01 to 3.79; P = 0.624).
CONCLUSION: A419V is not an important LRRK2 risk variant in our Asian cohort of patients with PD. Our data are further supported by a literature review which showed that 4 out of 6 published studies reported a negative association of this variant in PD.
Fulltext LRRK2 G2385R and R1628P mutations are associated with an increased risk of Parkinson's disease in the Malaysian population

Gopalai AA, Lim SY, Chua JY, Tey S, Lim TT, Mohamed Ibrahim N, et al.

Biomed Res Int, 2014;2014:867321.
PMID: 25243190 DOI: 10.1155/2014/867321

The LRRK2 gene has been associated with both familial and sporadic forms of Parkinson's disease (PD). The G2019S variant is commonly found in North African Arab and Caucasian PD patients, but this locus is monomorphic in Asians. The G2385R and R1628P variants are associated with a higher risk of developing PD in certain Asian populations but have not been studied in the Malaysian population. Therefore, we screened the G2385R and R1628P variants in 1,202 Malaysian subjects consisting of 695 cases and 507 controls. The G2385R and R1628P variants were associated with a 2.2-fold (P = 0.019) and 1.2-fold (P = 0.054) increased risk of PD, respectively. Our data concur with other reported findings in Chinese, Taiwanese, Singaporean, and Korean studies.
Fulltext Parkinson's Disease Diagnosis and Severity Assessment Using Ground Reaction Forces and Neural Networks

Veeraragavan S, Gopalai AA, Gouwanda D, Ahmad SA

Front Physiol, 2020;11:587057.
PMID: 33240106 DOI: 10.3389/fphys.2020.587057

Gait analysis plays a key role in the diagnosis of Parkinson's Disease (PD), as patients generally exhibit abnormal gait patterns compared to healthy controls. Current diagnosis and severity assessment procedures entail manual visual examinations of motor tasks, speech, and handwriting, among numerous other tests, which can vary between clinicians based on their expertise and visual observation of gait tasks. Automating gait differentiation procedure can serve as a useful tool in early diagnosis and severity assessment of PD and limits the data collection to solely walking gait. In this research, a holistic, non-intrusive method is proposed to diagnose and assess PD severity in its early and moderate stages by using only Vertical Ground Reaction Force (VGRF). From the VGRF data, gait features are extracted and selected to use as training features for the Artificial Neural Network (ANN) model to diagnose PD using cross validation. If the diagnosis is positive, another ANN model will predict their Hoehn and Yahr (H&Y) score to assess their PD severity using the same VGRF data. PD Diagnosis is achieved with a high accuracy of 97.4% using simple network architecture. Additionally, the results indicate a better performance compared to other complex machine learning models that have been researched previously. Severity Assessment is also performed on the H&Y scale with 87.1% accuracy. The results of this study show that it is plausible to use only VGRF data in diagnosing and assessing early stage Parkinson's Disease, helping patients manage the symptoms earlier and giving them a better quality of life.
Fulltext The Association of Falls with Instability: An Analysis of Perceptions and Expectations toward the Use of Fall Detection Devices Among Older Adults in Malaysia

Abdul Rahman K, Ahmad SA, Che Soh A, Ashari A, Wada C, Gopalai AA

Front Public Health, 2021;9:612538.
PMID: 33681130 DOI: 10.3389/fpubh.2021.612538

Background: Falls are a significant incident among older adults affecting one in every three individuals aged 65 and over. Fall risk increases with age and other factors, namely instability. Recent studies on the use of fall detection devices in the Malaysian community are scarce, despite the necessity to use them. Therefore, this study aimed to investigate the association between the prevalence of falls with instability. This study also presents a survey that explores older adults' perceptions and expectations toward fall detection devices. Methods: A cross-sectional survey was conducted involving 336 community-dwelling older adults aged 50 years and older; based on randomly selected participants. Data were analyzed using quantitative descriptive analysis. Chi-square test was conducted to investigate the associations between self-reported falls with instability, demographic and walking characteristics. Additionally, older adults' perceptions and expectations concerning the use of fall detection devices in their daily lives were explored. Results: The prevalence of falls was 28.9%, where one-quarter of older adults fell at least once in the past 6 months. Participants aged 70 years and older have a higher fall percentage than other groups. The prevalence of falls was significantly associated with instability, age, and walking characteristics. Around 70% of the participants reported having instability issues, of which over half of them fell at least once within 6 months. Almost 65% of the participants have a definite interest in using a fall detection device. Survey results revealed that the most expected features for a fall detection device include: user-friendly, followed by affordably priced, and accurate. Conclusions: The prevalence of falls in community-dwelling older adults is significantly associated with instability. Positive perceptions and informative expectations will be used to develop an enhanced fall detection incorporating balance monitoring system. Our findings demonstrate the need to extend the fall detection device features aiming for fall prevention intervention.
Fulltext Muscles Affecting Minimum Toe Clearance

Perera CK, Gopalai AA, Ahmad SA, Gouwanda D

Front Public Health, 2021;9:612064.
PMID: 34136448 DOI: 10.3389/fpubh.2021.612064

The aim of this study was to investigate how the anterior and posterior muscles in the shank (Tibialis Anterior, Gastrocnemius Lateralis and Medialis), influence the level of minimum toe clearance (MTC). With aging, MTC deteriorates thus, greatly increasing the probability of falling or tripping. This could result in injury or even death. For this study, muscle activity retention taping (MART) was used on young adults, which is an accepted method of simulating a poor MTC-found in elderly gait. The subject's muscle activation was measured using surface electromyography (SEMG), and the kinematic parameters (MTC, knee and ankle joint angles) were measured using an optical motion capture system. Our results indicate that MART produces significant reductions in MTC (P < α), knee flexion (P < α) and ankle dorsiflexion (P < α), as expected. However, the muscle activity increased significantly, contrary to the expected result (elderly individuals should have lower muscle activity). This was due to the subject's muscle conditions (healthy and strong), hence the muscles worked harder to counteract the external restriction. Yet, the significant change in muscle activity (due to MART) proves that the shank muscles do play an important role in determining the level of MTC. The Tibialis Anterior had the highest overall muscle activation, making it the primary muscle active during the swing phase. With aging, the shank muscles (specifically the Tibialis Anterior) would weaken and stiffen, coupled with a reduced joint range of motion. Thus, ankle-drop would increase-leading to a reduction in MTC.
Fulltext Improving Fall Detection Devices for Older Adults Using Quality Function Deployment (QFD) Approach

Abdul Rahman K, Ahmad SA, Che Soh A, Ashari A, Wada C, Gopalai AA

Gerontol Geriatr Med, 2023;9:23337214221148245.
PMID: 36644687 DOI: 10.1177/23337214221148245

Engineering invention must be in tandem with public demands. Often it is difficult to identify the priorities of consumers where technological advancement is needed. In line with the global challenge of increasing fall prevalence among older adults, providing prevention solutions is the key. This study aims at developing an improved fall detection device using an approach called Quality Function Deployment (QFD). The goal is to investigate features to incorporate in existing device from consumer's perspectives. A three-phases design process is constructed; (1) Questionnaire, (2) Ishikawa Method, and (3) QFD. The proposed method begins with identifying customer needs as the requirement analysis, followed by a method to convert them to design specifications to be added in a fall detection device using QFD tool. As the top feature is monitoring balance, the new improved fall detection devices incorporating balance features will help older adults to monitor their level of risk of falling.
Determining level of postural control in young adults using force-sensing resistors

Gopalai AA, Senanayake SM, Gouwanda D

IEEE Trans Inf Technol Biomed, 2011 Jul;15(4):608-14.
PMID: 21478080 DOI: 10.1109/TITB.2011.2140378

A force-sensing platform (FSP), sensitive to changes of the postural control system was designed. The platform measured effects of postural perturbations in static and dynamic conditions. This paper describes the implementation of an FSP using force-sensing resistors as sensing elements. Real-time qualitative assessment utilized a rainbow color scale to identify areas with high force concentration. Postprocessing of the logged data provided end-users with quantitative measures of postural control. The objective of this research was to establish the feasibility of using an FSP to test and gauge human postural control. Tests were conducted in eye open and eye close states. Readings obtained were tested for repeatability using a one-way analysis of variance test. The platform gauged postural sway by measuring the area of distribution for the weighted center of applied pressure at the foot. A fuzzy clustering algorithm was applied to identify regions of the foot with repetitive pressure concentration. Potential application of the platform in a clinical setting includes monitoring rehabilitation progress of stability dysfunction. The platform functions as a qualitative tool for initial, on-the-spot assessment, and quantitative measure for postacquisition assessment on balance abilities.
Musculoskeletal Gait Simulation to Investigate Biomechanical Effect of Knee Brace

Yap YT, Gouwanda D, Gopalai AA, Chong YZ

J Biomech Eng, 2023 Feb 01;145(2).
PMID: 36082472 DOI: 10.1115/1.4055564

Musculoskeletal modeling and simulation have been an emerging trend in human gait analysis. It allows the user to isolate certain biomechanical conditions and elucidate the dynamics of joints and muscles. This study used an open-source musculoskeletal modeling and simulation tool, opensim to investigate the biomechanical effect of knee brace. It collected gait data from thirty-eight participants and examined the gait spatio-temporal parameters, joint angles, and joint moments. Static optimization was performed to estimate the lower extremity muscle force. Statistical analysis was conducted to identify the difference between normal and braced gaits. The results demonstrated the feasibility of this method to investigate the interaction and coordination of lower extremity joints and muscles. The knee brace constrained the range of the motion of the knee during walking. It also changed the walking speed, step length, and stance-to-swing ratio. Several significant differences were found in the joint moments and muscle forces of the rectus femoris, gastrocnemius, soleus and tibialis anterior. Musculoskeletal modeling and simulation tool offers a less invasive and practical alternative to analyze human motion. It also provides a means to investigate the effect of medical devices such as knee brace, which can be potentially beneficial for the future design and development of such devices and for the derivation of future rehabilitation treatment to improve patient's gait.
Estimation of vertical ground reaction force during running using neural network model and uniaxial accelerometer

Ngoh KJ, Gouwanda D, Gopalai AA, Chong YZ

J Biomech, 2018 07 25;76:269-273.
PMID: 29945786 DOI: 10.1016/j.jbiomech.2018.06.006

Wearable technology has been viewed as one of the plausible alternatives to capture human motion in an unconstrained environment, especially during running. However, existing methods require kinematic and kinetic measurements of human body segments and can be complicated. This paper investigates the use of neural network model (NN) and accelerometer to estimate vertical ground reaction force (VGRF). An experimental study was conducted to collect sufficient samples for training, validation and testing. The estimated results were compared with VGRF measured using an instrumented treadmill. The estimates yielded an average root mean square error of less than 0.017 of the body weight (BW) and a cross-correlation coefficient greater than 0.99. The results also demonstrated that NN could estimate impact force and active force with average errors ranging between 0.10 and 0.18 of BW at different running speeds. Using NN and uniaxial accelerometer can (1) simplify the estimation of VGRF, (2) reduce the computational requirement and (3) reduce the necessity of multiple wearable sensors to obtain relevant parameters.
Real-time stability measurement system for postural control

Gopalai AA, Senanayake SM, Kiong LC, Gouwanda D

J Bodyw Mov Ther, 2011 Oct;15(4):453-64.
PMID: 21943619 DOI: 10.1016/j.jbmt.2010.10.005

A method for assessing balance, which was sensitive to changes in the postural control system is presented. This paper describes the implementation of a force-sensing platform, with force sensing resistors as the sensing element. The platform is capable of measuring destabilized postural perturbations in dynamic and static postural conditions. Besides providing real-time qualitative assessment, the platform quantifies the postural control of the subjects. This is done by evaluating the weighted center of applied pressure distribution over time. The objective of this research was to establish the feasibility of using the force-sensing platform to test and gauge the postural control of individuals. Tests were conducted in Eye Open and Eye Close states on Flat Ground (static condition) and the balance trainer (dynamic condition). It was observed that the designed platform was able to gauge the sway experienced by the body when subject's states and conditions changed.
The effect of asymmetrical gait induced by unilateral knee brace on the knee flexor and extensor muscles

Yap YT, Gouwanda D, Gopalai AA, Chong YZ

Med Biol Eng Comput, 2021 Mar;59(3):711-720.
PMID: 33625670 DOI: 10.1007/s11517-021-02337-7

Asymmetrical stiff knee gait is a mechanical pathology that can disrupt lower extremity muscle coordination. A better understanding of this condition can help identify potential complications. This study proposes the use of dynamic musculoskeletal modelling simulation to investigate the effect of induced mechanical perturbation on the kneeand to examine the muscle behaviour without invasive technique. Thirty-eight healthy participants were recruited. Asymmetrical gait was simulated using knee brace. Knee joint angle, joint moment and knee flexor and extensor muscle forces were computed using OpenSim. Differences inmuscle force between normal and abnormal conditions were investigated using ANOVA and Tukey-Kramer multiple comparison test.The results revealed that braced knee experienced limited range of motion with smaller flexion moment occuring at late swing phase. Significant differences were found in all flexormuscle forces and in several extensor muscle forces (p<0.05). Normal knee produced larger flexor muscle force than braced knee. Braced knee generated the largest extensor muscle force at early swing phase. In summary, musculoskeletal modelling simulation can be a computational tool to map and detect the differences between normal and asymmetrical gaits.
Fulltext Effects of powered ankle-foot orthoses mass distribution on lower limb muscle forces-a simulation study

Marconi G, Gopalai AA, Chauhan S

Med Biol Eng Comput, 2023 May;61(5):1167-1182.
PMID: 36689083 DOI: 10.1007/s11517-023-02778-2

This simulation study aimed to explore the effects of mass and mass distribution of powered ankle-foot orthoses, on net joint moments and individual muscle forces throughout the lower limb. Using OpenSim inverse kinematics, dynamics, and static optimization tools, the gait cycles of ten subjects were analyzed. The biomechanical models of these subjects were appended with ideal powered ankle-foot orthoses of different masses and actuator positions, as to determine the effect that these design factors had on the subject's kinetics during normal walking. It was found that when the mass of the device was distributed more distally and posteriorly on the leg, both the net joint moments and overall lower limb muscle forces were more negatively impacted. However, individual muscle forces were found to have varying results which were attributed to the flow-on effect of the orthosis, the antagonistic pairing of muscles, and how the activity of individual muscles affect each other. It was found that mass and mass distribution of powered ankle-foot orthoses could be optimized as to more accurately mimic natural kinetics, reducing net joint moments and overall muscle forces of the lower limb, and must consider individual muscles as to reduce potentially detrimental muscle fatigue or muscular disuse. OpenSim modelling method to explore the effect of mass and mass distribution on muscle forces and joint moments, showing potential mass positioning and the effects of these positions, mass, and actuation on the muscle force integral.
A robust real-time gait event detection using wireless gyroscope and its application on normal and altered gaits

Gouwanda D, Gopalai AA

Med Eng Phys, 2015 Feb;37(2):219-25.
PMID: 25619613 DOI: 10.1016/j.medengphy.2014.12.004

Gait events detection allows clinicians and biomechanics researchers to determine timing of gait events, to estimate duration of stance phase and swing phase and to segment gait data. It also aids biomedical engineers to improve the design of orthoses and FES (functional electrical stimulation) systems. In recent years, researchers have resorted to using gyroscopes to determine heel-strike (HS) and toe-off (TO) events in gait cycles. However, these methods are subjected to significant delays when implemented in real-time gait monitoring devices, orthoses, and FES systems. Therefore, the work presented in this paper proposes a method that addresses these delays, to ensure real-time gait event detection. The proposed algorithm combines the use of heuristics and zero-crossing method to identify HS and TO. Experiments involving: (1) normal walking; (2) walking with knee brace; and (3) walking with ankle brace for overground walking and treadmill walking were designed to verify and validate the identified HS and TO. The performance of the proposed method was compared against the established gait detection algorithms. It was observed that the proposed method produced detection rate that was comparable to earlier reported methods and recorded reduced time delays, at an average of 100 ms.
A triple compound pendulum model to analyse the effect of an ankle-foot orthosis on swing phase kinematics

Marconi G, Gopalai AA, Chauhan S

Med Eng Phys, 2023 Feb;112:103951.
PMID: 36842774 DOI: 10.1016/j.medengphy.2023.103951

Powered ankle-foot orthoses can be utilised to overcome gait abnormalities such as foot drop; however, normal gait is rarely restored with compensatory gait patterns arising and prevalence of gait asymmetry. Therefore, this study aims to determine the effect of orthosis mass and mass distribution on the swing phase of gait, to understand residual gait asymmetry with orthosis use. Using a triple compound pendulum model, which accounts for mass distribution of the limb and orthosis, the swing phase of gait is simulated in terms of natural dynamics and the effect of an orthosis on kinematic parameters is quantitatively determined. It was found that additional mass causes faster and shorter steps on the affected side due to rapid knee extension and reduced hip flexion, with particular actuator positions and natural cadence causing varying severity of these effects. Our study suggests that this model could be used as a preliminary design tool to identify subject specific optimum orthosis mass distribution of a powered ankle-foot orthosis, without the need for motion data or experimental trials. This optimisation intends to more accurately mimic natural swing phase kinematics, consequently allowing for the reduction in severity of gait asymmetry and the potential to improve rehabilitative outcomes.
Fulltext LRRK2 N551K and R1398H variants are protective in Malays and Chinese in Malaysia: A case-control association study for Parkinson's disease

Gopalai AA, Lim JL, Li HH, Zhao Y, Lim TT, Eow GB, et al.

Mol Genet Genomic Med, 2019 Nov;7(11):e604.
PMID: 31487119 DOI: 10.1002/mgg3.604

BACKGROUND: The LRRK2 gene is associated with Parkinson's disease (PD) as a number of mutations within the gene have been shown to be susceptibility factors. Studies on various global populations have determined that mutations such as G2019S, G2385R, and R1628P in LRRK2 increase the risk of developing PD while the N551K-R1398H haplotype is associated with conferring protection against developing PD. Here we report a study looking at the N551K and R1398H variants for the first time in the Malaysian population.
METHODS: Cases (523) which conformed to the United Kingdom PD Brain Bank Criteria for PD were recruited through trained neurologists and age- and ethnically matched controls (491) were individuals free of any neurological disorder. The N551K and R1398H mutations were genotyped using the Taqman SNP genotyping assay.
RESULTS: A significant protective association for N551K was found in those of Malay ancestry, with a protective trend seen for R1398H. A meta-analysis of Chinese individuals in this cohort with other published cohorts of Chinese ancestry indicated a significant protective role for N551K and R1398H.
CONCLUSION: This study reports that the N551K-R1398H haplotype is also relevant to the Malaysian population, with a significant protective effect found in those of Malay and Chinese ancestries.
Postural Control and Adaptation Strategy of Young Adults on Unstable Surface

Lai QQ, Gouwanda D, Gopalai AA

Motor Control, 2023 Apr 01;27(2):179-193.
PMID: 36216337 DOI: 10.1123/mc.2021-0138

Balance control is essential for postural adjustment in physical activities. This study investigates the behavior of human postural control and the coordination and adaptation strategy of hip, knee, and ankle when standing on an unstable surface. Twenty participants were recruited. Four different conditions were investigated: a quiet bipedal stance with eyes open and eyes closed, and standing on an unstable surface with eyes open and eyes closed. Other than the joint angle, the standard body sway measures, such as sway area and sway velocity, were computed. A nonlinear time series measure, that is, sample entropy, was used to determine the regularity of the time series and body adaptability to change and perturbation. The results show that the body sway increases as the difficulty increases. This study also confirms the coordination of the hip, knee, and ankle to maintain body balance on the unstable surface by decreasing the joint angle and adopting a lower posture. Even though the individual joint has lower sample entropy value and is deemed to be rigid and less adaptive to perturbation, the postural control exhibits higher sample entropy value, particularly in the anterior-posterior direction, and has the ability to stabilize the body by manipulating the joints simultaneously. These outcomes suggest that an unstable surface not only challenges the human postural control, but also reduces the hip, knee, and ankle adaptability to perturbation, thus making it a great tool to train body balance.
Association study of MCCC1/LAMP3 and DGKQ variants with Parkinson's disease in patients of Malay ancestry

Lim JL, Ng EY, Lim SY, Tan AH, Abdul-Aziz Z, Ibrahim KA, et al.

Neurol Sci, 2021 Oct;42(10):4203-4207.
PMID: 33559030 DOI: 10.1007/s10072-021-05056-x

BACKGROUND: Genome-wide association studies (GWAS) have shown that variants in the 3-methylcrotonyl-CoA carboxylase (MCCC1)/lysosome-associated membrane protein 3 (LAMP3) loci (rs10513789, rs12637471, rs12493050) reduce the risk of Parkinson's disease (PD) in Caucasians, Chinese and Ashkenazi-Jews while the rs11248060 variant in the diacylglycerol kinase theta (DGKQ) gene increases the risk of PD in Caucasian and Han Chinese cohorts. However, their roles in Malays are unknown. Therefore, this study aims to investigate the association of these variants with the risk of PD in individuals of Malay ancestry.
METHODS: A total of 1114 subjects comprising of 536 PD patients and 578 healthy controls of Malay ancestry were recruited and genotyped using Taqman® allelic discrimination assays.
RESULTS: The G allele of rs10513789 (OR = 0.83, p = 0.001) and A allele of rs12637471 (OR = 0.79, p = 0.007) in the MCCC1/LAMP3 locus were associated with a protective effect against developing PD in the Malay population. A recessive model of penetrance showed a protective effect of the GG genotype for rs10513789 and the AA genotype for rs12637471. No association with PD was found with the other MCCC1/LAMP3 rs12493050 variant or with the DGKQ (rs11248060) variant. No significant associations were found between the four variants with the age at PD diagnosis.
CONCLUSION: MCCC1/LAMP3 variants rs10513789 and rs12637471 protect against PD in the Malay population.
Fulltext Simulation of passive exotendon assistive device for agricultural harvesting task

Chan YS, Teo YX, Gouwanda D, Nurzaman SG, Gopalai AA

Phys Eng Sci Med, 2023 Dec;46(4):1375-1386.
PMID: 37493930 DOI: 10.1007/s13246-023-01305-9

This study proposes and investigates the feasibility of the passive assistive device to assist agricultural harvesting task and reduce the Musculoskeletal Disorder (MSD) risk of harvesters using computational musculoskeletal modelling and simulations. Several passive assistive devices comprised of elastic exotendon, which acts in parallel with different back muscles (rectus abdominis, longissimus, and iliocostalis), were designed and modelled. These passive assistive devices were integrated individually into the musculoskeletal model to provide passive support for the harvesting task. The muscle activation, muscle force, and joint moment were computed with biomechanical simulations for unassisted and assisted motions. The simulation results demonstrated that passive assistive devices reduced muscle activation, muscle force, and joint moment, particularly when the devices were attached to the iliocostalis and rectus abdominis. It was also discovered that assisting the longissimus muscle can alleviate the workload by distributing a portion of it to the rectus abdominis. The findings in this study support the feasibility of adopting passive assistive devices to reduce the MSD risk of the harvesters during agricultural harvesting. These findings can provide valuable insights to the engineers and designers of physical assistive devices on which muscle(s) to assist during agricultural harvesting.
Fulltext The effects of mechanical noise bandwidth on balance across flat and compliant surfaces

Khor JZS, Gopalai AA, Lan BL, Gouwanda D, Ahmad SA

Sci Rep, 2021 06 10;11(1):12276.
PMID: 34112840 DOI: 10.1038/s41598-021-91422-w

Although the application of sub-sensory mechanical noise to the soles of the feet has been shown to enhance balance, there has been no study on how the bandwidth of the noise affects balance. Here, we report a single-blind randomized controlled study on the effects of a narrow and wide bandwidth mechanical noise on healthy young subjects' sway during quiet standing on firm and compliant surfaces. For the firm surface, there was no improvement in balance for both bandwidths-this may be because the young subjects could already balance near-optimally or optimally on the surface by themselves. For the compliant surface, balance improved with the introduction of wide but not narrow bandwidth noise, and balance is improved for wide compared to narrow bandwidth noise. This could be explained using a simple model, which suggests that adding noise to a sub-threshold pressure stimulus results in markedly different frequency of nerve impulse transmitted to the brain for the narrow and wide bandwidth noise-the frequency is negligible for the former but significantly higher for the latter. Our results suggest that if a person's standing balance is not optimal (for example, due to aging), it could be improved by applying a wide bandwidth noise to the feet.

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