Lifting Frequency Research Articles

Ergonomic Risk Assessment for Manual Handling Activities in Automotive Workshop

Ergonomic risk assessment tools are tools that have been designed to solve the problem of ergonomics in the workplace from manual material handling activities. The objective of this study is to investigate Musculoskeletal Discomfort among workers related to manual handling activities using Cornell Musculoskeletal Discomfort Questionnaires (CMDQ); to assess an ergonomics risk factor among workers related to manual handling activities using Manual Handling Assessment Chart (MAC), NIOSH Lifting Equation(NLE), and Key Indicator Method for Manual Handling Operation (KIM-MHO) method and; to compare the results between CMDQ and assessment tools. This case study was conducted in Parit Raja, Johor, Malaysia involving 34 male mechanics workers. The tools used are as stated in the objective with the help of measurement tools such as a goniometer. The result of the CMDQ reveals that the body part with the highest discomfort level among the workers in the lower back, shoulder right and shoulder left with the percentage from the total discomfort score of 20.91%, 13.57%, and 13.36% respectively. From the result of the assessments, it is concluded that the highest risk factor contributing to the MSDs is the bad posture of the worker during the manual handling operation followed by the frequency of lifting and the weight of the load. By comparing assessment tools, the first comparison is made between the CMDQ versus KIM-MHO, MAC Tools and NLE. In this comparison that, it is highlighted the result type from CMDQ are different from the KIM-MHO, MAC Tools and NLE as its questionnaire result shows us the discomforts levels on the body of workers and the body parts affected on their body for the last seven days but the assessment tools results show us the risk factor that contributes to the MSDs. For the comparison between the three assessment tools, it can be said that the tools that have the highest correlation with CMDQ are MAC Tools. In conclusion, most workers suffer from MSDs in their lower back due to their bad posture during manual handling. KIM-MHO is the best assessment tool among the three as it has the highest significance value while being the easiest tool to be used.

Effect of internal fluid and external shear flow on vortex-induced vibration response of drilling riser

This study introduces a new numerical tool for exploring the impact of various dimensionless parameters on vortex-induced vibration in risers. The tool is based on an innovative coupled model of a riser and a modified wake oscillator, which integrates the effects of internal axial flow and external cross flow. The dynamic equations are discretized using a second-order finite difference method in both time and space domains. Simulations reveal multi-modal behavior in the riser's vortex-induced vibration response, including lock-in and synchronous vibration. It is demonstrated that increasing internal flow velocity reduces response mode number and periodicity, and the riser becomes unstable when centrifugal force equals axial tension. The study also shows that higher maximum external flow velocities increase the frequency components of the riser's response and vortex shedding frequency range. A quarter-period phase difference between structural displacement and lift coefficient is observed, while lift coefficient and structural velocity remain synchronous. The lift frequency, as a function of position, jumps between neighboring sections of the riser. This tool provides a foundation for future research, with the cases explored serving as examples of its potential applications in investigating VIV phenomena.

Wavelength-induced shedding frequency modulation of seal whisker inspired cylinders

The spanwise undulated cylinder geometry inspired by seal whiskers has been shown to alter shedding frequency and reduce fluid forces significantly compared to smooth cylindrical geometry. Prior research has parameterized the whisker-inspired geometry and demonstrated the relevance of geometric variations on force reduction properties. Among the geometric parameters, undulation wavelength was identified as a significant contributor to forcing changes. To analyze the effect of undulation wavelength, a thorough investigation isolating changes in wavelength is performed to expand upon previous research that parameterized whisker-inspired geometry and the relevance of geometric variations on the force reduction properties. A set of five whisker-inspired models of varying wavelength are computationally simulated at a Reynolds number of 250 and compared with an equivalent aspect ratio smooth elliptical cylinder. Above a critical non-dimensional value, the undulation wavelength reduces the amplitude and frequency of vortex shedding accompanied by a reduction in oscillating lift force. Frequency shedding is tied to the creation of wavelength-dependent vortex structures which vary across the whisker span. These vortices produce distinct shedding modes in which the frequency and phase of downstream structures interact to decrease the oscillating lift forces on the whisker model with particular effectiveness around the wavelength values typically found in nature. The culmination of these location-based modes produces a complex and spanwise-dependent lift frequency spectra at those wavelengths exhibiting maximum force reduction. Understanding the mechanisms of unsteady force reduction and the relationship between undulation wavelength and frequency spectra is critical for the application of this geometry to vibration tuning and passive flow control for vortex-induced vibration (VIV) reduction.

Silencing of secreted phosphoprotein 1 attenuates sciatic nerve injury-induced neuropathic pain: Regulating extracellular signal-regulated kinase and neuroinflammatory signaling pathways.

Neuropathic pain (NP) is a chronic pathological pain that affects the quality of life and is a huge medical burden for affected patients. In this study, we aimed to explore the effects of secreted phosphoprotein 1 (SPP1) on NP. We established a chronic constriction injury (CCI) rat model, knocked down SPP1 via an intrathecal injection, and/or activated the extracellular signal-regulated kinase (ERK) pathway with insulin-like growth factor 1 (IGF-1) treatment. Pain behaviors, including paw withdrawal threshold (PWT), paw withdrawal latency (PWL), lifting number, and frequency, were assessed. After sacrificing rats, the L4-L5 dorsal root ganglion was collected. Then, SPP1 levels were determined using quantitative polymerase chain reaction (qPCR) and western blot analysis. The levels of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-6, IL-10, epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), and transforming growth factor (TGF)-β were determined using qPCR and enzyme-linked immunosorbent assay. The levels of ERK pathway factors were determined via western blot analysis. We found that CCI decreased PWT and PWL, increased the lifting number and frequency, and upregulated SPP1 levels. The loss of SPP1 reversed these CCI-induced effects. Additionally, CCI upregulated IL-1β, TNF-α, IL-6, EGF, and VEGF levels, downregulated TGF-β levels, and activated the ERK pathway, while silencing of SPP1 abrogated these CCI-induced effects. Moreover, IGF-1 treatment reversed the effects of SPP1 loss. The data indicate that silencing SPP1 attenuates NP via inactivation of the ERK pathway, suggesting that SPP1 may be a promising target for NP treatment.

Risk factors of musculoskeletal disorders in loading and unloading tasks of couriers.

The use of home delivery services has expanded due to coronavirus disease - 2019, and couriers' high level of work intensity has become a severe social issue in various nations. This study investigates the risk factors of musculoskeletal disorders (MSDs) caused by frequent loading and unloading actions, known to be the most demanding tasks for couriers. A self-report survey and post-hoc interview were employed to collect personal information, task frequency, and the incidence of MSDs. Frequent actions during loading and unloading packages were identified, and the Rapid Entry Body Assessment (REBA) and National Institute for Occupational Safety and Health (NIOSH) lifting equations were assessed. Approximately 29.5% of the 44 subjects suffered from MSDs, and identify the types of actions that frequently occur during loading and unloading packages. According to the REBA survey, 60% of the responses for both loading and unloading are distributed within the risk range of 8-13 points, suggesting a high risk (mean REBA score: 8.8 (loading), 8.5 (unloading)). In every case, NIOSH determined that the lifting index (LI) was harmful (mean LI: 1.62). Thereby, the bending or twisting posture of the hands and neck, long horizontal distance between the packages and the body, and high lifting frequency were identified as major problems. The study identified a very high level of musculoskeletal risk for couriers, and the detailed working methods and body parts vulnerable to MSDs.

First-trimester occupational exposures and hypertensive disorders of pregnancy among US nurses.

Limited and conflicting data exist regarding the impact of first-trimester nursing occupational exposures on hypertensive disorders of pregnancy (HDP). To investigate whether first-trimester night shift work, work hours and work-related activities are associated with HDP. We conducted a cross-sectional analysis of 6610 women within the Nurses' Health Study II. We used multiple logistic regression to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) for the relation of occupational exposures to HDP. Nine per cent of respondents reported an HDP in the index pregnancy (gestational hypertension: n = 354, 5%, preeclampsia: n = 222, 3%). First-trimester fixed or rotating night shift work was not significantly associated with gestational hypertension or preeclampsia compared to day shift work only. Compared to those working 21-40 h/week, working overtime (≥41 h/week) was not associated with gestational hypertension but was associated with 43% higher odds of preeclampsia (95% CI 1.02, 2.00). For part-time work (≤20 h/week), the OR was 0.76 (95% CI 0.56, 1.02) for gestational hypertension and 0.64 (95% CI 0.43, 0.97) for preeclampsia. The odds of preeclampsia were 3% higher per additional hour worked per week (95% CI 1.01-1.04). Compared to 0-4 h spent standing or walking per day, standing or walking ≥9 h daily was associated with 32% lower odds of gestational hypertension (95% CI 0.47, 0.99) but was not significantly associated with preeclampsia. Frequency of heavy lifting was not associated with either hypertensive disorder or pregnancy. Among nurses, working overtime was associated with higher odds of preeclampsia.

Effect of muscular fatigue on the cumulative lumbar damage during repetitive lifting task: a comparative study of damage calculation methods

Several methods have been put forward to quantify cumulative loads; however, limited evidence exists as to the subsequent damages and the role of muscular fatigue. The present study assessed whether muscular fatigue could affect cumulative damage imposed on the L5–S1 joint. Trunk muscle electromyographic (EMG) activities and kinematics/kinetics of 18 healthy male individuals were evaluated during a simulated repetitive lifting task. A traditional EMG-assisted model of the lumbar spine was modified to account for the effect of erector spinae fatigue. L5–S1 compressive loads for each lifting cycle were estimated based on varying (i.e. actual), fatigue-modified, and constant Gain factors. The corresponding damages were integrated to calculate the cumulative damage. Moreover, the damage calculated for one lifting cycle was multiplied by the lifting frequency, as the traditional approach. Compressive loads and the damages obtained through the fatigue-modified model were predicted in close agreement with the actual values. Similarly, the difference between actual damages and those driven by the traditional approach was not statistically significant (p = 0.219). However, damages based on a constant Gain factor were significantly greater than those based on the actual (p = 0.012), fatigue-modified (p = 0.017), and traditional (p = 0.007) approaches. Practitioner summary: In this study, we managed to include the effect of muscular fatigue on cumulative lumbar damage calculations. Including the effect of muscular fatigue leads to an accurate estimation of cumulative damages while eliminating computational complexity. However, using the traditional approach also appears to provide acceptable estimates for ergonomic assessments.

Design and characteristic analysis of a novel deformation-controllable piezoelectric vibration energy harvester for low frequency

Vibration energy harvesting using the piezoelectric effect is becoming a promising solution to the sustainable green power source for low-power portable and wireless electronics. To harvest low-frequency vibration energy and prevent the damage of piezoelectric vibrator due to the excessive deformation, a novel deformation-controllable piezoelectric vibration energy harvester (D-CPVEH) by using a wedge cam to limit the maximum deformation of the cantilevered piezoelectric vibrator is proposed in this paper. The cam structure can drive the pre-bending piezoelectric vibrator to produce a controllable-amplitude and unidirectional deformation, thereby improving the reliability of the harvester significantly. To verify the feasibility of the proposed principle and design, theoretical analysis and numerical simulation are firstly performed, and then the influences of system parameters on the dynamic response of the D-CPVEH are analyzed in terms of amplitude ratio of the cam and deformation of the vibrator. Afterwards, a prototype is fabricated and tested in terms of frequency response characteristics. The simulation and experimental results show that the maximum deformation of the piezoelectric vibrator can effectively be limited by introducing the cam structure. Besides, it demonstrates that the spring stiffness, additional mass, cam lift, cam angle and excitation frequency exert a significant effect on the amplitude ratio of the cam, the deformation of the piezoelectric vibrator, the output voltage and the maximum voltage of the harvester, and the optimal operating bandwidth. The maximum generated voltage increases while the corresponding optimal operating bandwidth decreases with the increase of the cam lift. It is found that the maximum voltage is basically independent of other structural parameters except for the cam lift. Furthermore, the optimal operating bandwidth can be effectively adjusted by the spring stiffness, additional mass and cam angle to adapt to the broadband low-frequency vibration environments. The testing result shows that the D-CPVEH can achieve the maximum power of 2.58 mW at 5.5 Hz with the optimal load resistance of 30 kΩ.

Effects of Occupational Stress and Frequency of Lifting Heavy Loads on Low Back Pain in Health Workers: A Meta Analysis

Background: Health workers have a high risk for experiencing symptoms of disorders of the musculoskeletal system such as pain, injury, trauma, and other disorders. According to the World Health Organization (WHO), work-related musculoskeletal disorders or commonly called work-related musculoskeletal disorders (WRMDs) are injuries that include various inflammatory disorders or degenerative diseases associated with pain or functional disorders in the body.Subjects and Method: This study is a systematic review and meta-analysis with the following PICO, Population: Health workers. Intervention: High stress and high frequency of heavy lifting. Comparison: Low stress and low frequency of weight lifting. Outcome: Back pain. The articles used in this study were obtained from three databases, namely Google Scholar, Pubmed, and Science Direct. Keywords to search for articles “low back pain” “risk factors” “determinants” “predictors” AND “health workers” The articles included were full-text English with a cohort and cross-sectional study design from 2016 to 2021 and reported the adjusted odds ratio (aOR) in the multivariate analysis. The selection of articles was done by using PRISMA flow diagram. Articles were analyzed using the Review Manager 5.3 application.Results: A total of 5 cohort and 10 cross-sectional studies, ten articles included nurses as research respondents, four articles included overall medical personnel, and one article included ambulance workers. Research locations are in Denmark, Saudi Arabia, China, Japan, Malaysia, Iran, Brazil Italy, Australia, Yemen, Estonia, and Ethiopia with medical workers who have low levels of job stress (aOR= 2.52; 95% CI= 2.15 to 2.96; p< 0.001) and it can be concluded that medical workers with frequent heavy lifting have a risk of experiencing back pain by 2.01 times compared to medical workers with infrequent weight lifting frequency (aOR= 2.01; 95% CI 1.23 to 3.18; p = 0.003).Conclusion: Medical workers with high levels of job stress and frequent heavy lifting are at risk for back pain. Keywords: back pain, stress, weight lifting. Correspondence:Ahmad Syauqi Mubarok. Masters Program of Public Health Sciences, Universitas Sebelas Maret, Jl. Ir. Sutami 36A, Surakarta 57126, Central Java. Email: syauqimubarok39@gmail.com. Mobile: 085741144248.

Numerical Investigation on Vortex-Induced Vibration over Circular Cylinder to be used for Energy Harvesting Application

Renewable energy is energy generated through inexhaustible processing resources, like sunlight, wind, etc. Existing and popular wind energy harvesting technology is wind turbine farms that have very high installation costs and demand strong wind flow to deliver sufficient power. Thus, wind energy generation based on the vortex-induced vibration-based energy harvester has become a more popular field of interest for many researchers. The vortex shedding produced by the unsteady incompressible flow over a bluff body has been used to excite the piezoelectric plate, generating electricity by its vibration. Hence generating an optimised vortex shedding and obtaining the optimised oscillation frequency. This paper investigates the computational fluid dynamics-based flow analysis over a smooth cylinder carrying a plate. The Reynolds number, Re, is 100 used for unsteady incompressible flow and the plate density ratio is varied from 5 – 40. The variation in lift and drag forces and frequency of vibration, and maximum vibration amplitude achieved by the piezoelectric plate is observed and determined. The results presented here help design a better and more efficient vortex-induced energy harvester.

Biomechanical assessment of a passive back-support exoskeleton during repetitive lifting and carrying: Muscle activity, kinematics, and physical capacity

Introduction: Most people have experienced low back pain (LBP) more or less in their lifetime. Heavier load weight could increase the risk of LBP, especially in repetitive lifting and carrying tasks. The risk could also increase with the frequency of lifting. This study aims to investigate the effects of a passive back-support exoskeleton (PBSE) on trunk muscle activation, kinematics, and physical capacity in a repetitive lifting task and a carrying task in consideration of load weights in a laboratory setting. Results: Results showed that using the PBSE, the activities of the thoracic erector spinae and lumbar erector spinae muscles were reduced significantly by nearly 7% MVC and 3% MVC in the repetitive lifting task and the carrying task, respectively. There was no significant effect of the PBSE on the spine kinematics and physical capacity. Practical Applications: This study supports the use of the PBSE to reduce trunk muscle activity in repetitive lifting and carrying tasks.

RISK FACTOR ANALYSIS OF LOW BACK PAIN IN EMPLOYEES OF DRINKING WATER STORE IN MEDAN SELAYANG SUB-DISTRICT

Background. Low back pain is defined as feeling of pain and discomfort in the area between the costal margin and inferior gluteal fold, with or without radiating pain. In Indonesia, LBP was fifth ranks in term of disability-adjusted life years (DALYs). Aim. This study aims to determine risk factors for LBP in employees of drinking water store in Medan Selayang sub-District, Medan. Method. This research is an observational analytic study with cross-sectional design. This study used consecutive sampling method. Minimum sample size in this study was 97 samples. Subjects in this study were employees of drinking water store in Medan Selayang sub-District. Data used in this study was primary data from samples through filling out questionnaires. Analysis used in this study was univariate analysis, bivariate with chi-square, and multivariate with logistic regression. Result. From 100 samples, 39 respondents (39%) experienced LBP. Based on bivariate analisis, p value ≤ 0.05 was found for age, body mass index, and duration of work. P value ≥ 0.05 was obtained for years of work and lifting frequency. Based on multivariate analysis with regression logistic, p value ≤ 0.05 was obtained for body mass index (p = 0.089) and work duration (p = 0.011) which indicated that work duration was the most dominant risk factor. Conclusion. There’s a relationship between age, body mass index, and work duration with the work duration being the most dominant risk factor for the incidence of low back pain in water gallon worker. .

A computer vision-based lifting task recognition method

Low-back musculoskeletal disorders (MSDs) are major cause of work-related injury among workers in manual material handling (MMH). Epidemiology studies show that excessive repetition is one of major risk factors of low-back MSDs. Thus, it is essential to monitor the frequency of lifting tasks for an ergonomics intervention. In the current field practice, safety practitioners need to manually observe workers to identify their lifting frequency, which is time consuming and labor intensive. In this study, we propose a method that can recognize lifting actions from videos using computer vision and deep neural networks. An open-source package OpenPose was first adopted to detect bony landmarks of human body in real time. Interpolation and scaling techniques were then applied to prevent missing points and offset different recording environments. Spatial and temporal kinematic features of human motion were then derived. These features were fed into long short-term memory networks for lifting action recognition. The results show that the F1-score of the lifting action recognition is 0.88. The proposed method has potential to monitor lifting frequency in an automated way and thus could lead to a more practical ergonomics intervention.

Centre of pressure parameters for the assessment of biomechanical risk in fatiguing frequency-dependent lifting activities.

Lifting tasks, among manual material handling activities, are those mainly associated with low back pain. In recent years, several instrumental-based tools were developed to quantitatively assess the biomechanical risk during lifting activities. In this study, parameters related to balance and extracted from the Centre of Pressure (CoP) data series are studied in fatiguing frequency-dependent lifting activities to: i) explore the possibility of classifying people with LBP and asymptomatic people during the execution of task; ii) examine the assessment of the risk levels associated with repetitive lifting activities, iii) enhance current understanding of postural control strategies during lifting tasks. Data were recorded from 14 asymptomatic participants and 7 participants with low back pain. The participants performed lifting tasks in three different lifting conditions (with increasing lifting frequency and risk levels) and kinetic and surface electromyography (sEMG) data were acquired. Kinetic data were used to calculated the CoP and parameters extracted from the latter show a discriminant capacity for the groups and the risk levels. Furthermore, sEMG parameters show a trend compatible with myoelectric manifestations of muscular fatigue. Correlation results between sEMG and CoP velocity parameters revealed a positive correlation between amplitude sEMG parameters and CoP velocity in both groups and a negative correlation between frequency sEMG parameters and CoP velocity. The current findings suggest that it is possible to quantitatively assess the risk level when monitoring fatiguing lifting tasks by using CoP parameters as well as identify different motor strategies between people with and without LBP.

Development of symptomatic pelvic organ prolapse over 10 years of mid-life follow-up is affected by occupational lifting and/or pushing for parous women

ObjectiveTo document the risk of new-onset symptomatic pelvic organ prolapse (POP) among perimenopausal women and examine whether occupational lifting and/or pushing is a risk factor in the development of POP over a 10-year follow-up window. Study designSecondary analysis of prospective, longitudinal data from the Study of Women's Health Across the Nation (SWAN) cohort study. Main outcome measuresWe analyzed women with current employment at the start of SWAN who were followed annually during mid-life. At baseline, women self-reported the frequency of occupational lifting and pushing, which was classified as Never, Infrequent (less than half the time), or Frequent (half the time or more) occupational lifting and/or pushing. Women were asked about new-onset symptomatic POP from the second to tenth annual follow-up. Modified Poisson regression was used to quantify crude and adjusted risk ratios (RRs) and 95 % confidence intervals (CIs) for POP according to load-bearing categories. Parous women were modelled separately, as initial analyses suggested effect modification by parity status. ResultsIn our sample of 1590 parous women, 8.2 % reported new-onset symptomatic POP over 10 years of follow-up. Multivariable analysis revealed that Infrequent (aRR 1.51, 95 % CI 1.04–2.20) and Frequent (aRR 2.03, 95 % CI 1.29–3.17) occupational lifting and/or pushing were associated with the development of POP. ConclusionFrequent occupational lifting and/or pushing significantly increased parous women's risk of developing POP symptoms. This strengthens existing evidence that occupational exposures can be risk factors for POP. Gender-based education and prevention strategies in the workplace and in primary health care are necessary to reduce the burden of this condition for mid-life women.

Evaluation of Incise Drape Lift Using 2% Chlorhexidine Gluconate/70% Isopropyl Alcohol Preoperative Skin Preparations in a Human Volunteer Knee Model.

BackgroundBefore surgery, skin is prepped with antiseptics to reduce risk of surgical site infections. An incise drape can be used as an additional modality to immobilize any remaining bacteria. Good adhesion of this drape is critical for infection prevention.MethodsThis is a randomized controlled study using a human volunteer knee model (n = 30) to evaluate the adhesion performance of an incise drape comparing 2 skin preparations. A new investigational 2% chlorhexidine gluconate/70% isopropyl alcohol skin prep (prep A) was compared with an existing skin prep containing the same active agents (prep B). Two samples of an iodine-impregnated incise drape were placed on each knee after prepping. Knees were flexed in dry conditions, under a saline-soaked gauze, and after saline lavage. The frequency of drape lift was recorded after each challenge.ResultsAfter dry flex, 4 of 60 samples (6.7%) had lifted on prep A and 0 on prep B (P = .125). After wet flex, 20 of 60 samples (33%) had lifted on prep A, whereas 42 of 60 samples (70%) had lifted on prep B (P < .0001). After lavage, 23 of 60 samples (38%) had lifted on prep A, whereas 48 of 60 samples (80%) had lifted on prep B (P < .0001). Both preps were well tolerated with minimal erythema and no edema, rash, dryness, or denudation observed. No adverse events were reported.ConclusionsPrep A resulted in reduced frequency of incise drape lift from skin under wet conditions in this model compared with prep B.

State-Space Modeling of Viscous Unsteady Aerodynamic Loads

In this paper, we summarize our recently developed viscous unsteady theory, which couples potential flow with the triple-deck boundary-layer theory. This approach provides a viscous extension of potential-flow unsteady aerodynamics. As such, a Reynolds-number-dependent transfer function is determined for unsteady lift. We then use the Wiener–Hammerstein structure to develop a finite-dimensional approximation of such an infinite-dimensional theory, presenting it in a state-space model. This novel nonlinear state-space model of viscous unsteady aerodynamic loads is expected to serve aerodynamicists better than the classical Theodorsen’s model because it captures viscous effects (that is, Reynolds number dependence) as well as nonlinearity and additional lag in the lift dynamics; it also allows simulation of arbitrary time-varying airfoil motions (not necessarily harmonic). Moreover, being in a state-space form makes it quite convenient for simulation and coupling with structural dynamics to perform aeroelasticity, flight dynamics analysis, and control design. We then develop a linearization of such a model, which enables analytical results. Subsequently, we derive an analytical representation of the viscous lift frequency response function: an explicit function of both the frequency and Reynolds number. We also develop a state-space model of the linearized response. We finally simulate the nonlinear and linear models to a nonharmonic small-amplitude pitching maneuver at a Reynolds number of 100,000 and compare the resulting lift and pitching moment with those obtained from potential flow; this is in reference to relatively higher-fidelity computations of the unsteady Reynolds-averaged Navier–Stokes equations.

Biomechanical risk in fatiguing frequency-dependent lifting activities: muscle coactivation in people with and without low back pain

Musculoskeletal diseases and disorders from biomechanical overload are very common among workers. In Italy in2019, occupational diseases of the osteomuscular system and connective tissue accounted for 66% of the total number ofdiseases reported to INAIL. Many factors can contribute to the establishment of a condition of biomechanical overloadand therefore to the onset of work-related musculoskeletal disorders (WMSDs). Among these, work-related low-backdisorders (WLBDs), caused mainly by handling heavy loads, are very common.In recent years, several methods have been developed to assess the risk of biomechanical overload, included in severalinternational standards (ISO-11228, ISO-11226, ISO/TR 12295 and 12296) aimed at identifying high-risk work activities and assessing the effectiveness of ergonomic interventions. Among the best known, with regard to the manual liftingof heavy loads, there is the Revised NIOSH Lifting Equation that, while presenting many advantages (cost-effectiveness,non-invasiveness, speed of application ...) at the same time also has limitations concerning mainly the high subjectivity(subject of scientific debate) and the impossibility of these methods to assess all work tasks.From these premises, it is clear the usefulness of being able to use new quantitative risk assessment methodologies,objectifiable and repeatable, which provide for the possibility of assessing the risk from biomechanical overload evenin modern working scenarios where the use of exoskeletons by workers and the sharing of working space with cobots isbecoming increasingly widespread. In fact, the methods currently used are incomplete and ineffective in assessing thereal impact that these technologies have on the health and safety of workers in Industry 4.0.Recent studies (some of which we were involved in) have introduced the possibilities offered by optoelectronic systems, inertial sensors (IMUs) and surface electromyography (sEMG), to integrate the most widely used observationalmethodologies. These modern technologies, evaluating how a subject moves his joints and uses his muscles during theexecution of a work task, can integrate the observational methods, quantify the elements that characterize the risk minimizing the evaluation errors caused by individual subjectivity and allow to carry out the assessment of biomechanicalrisk even in those areas where the currently most widespread methodologies are not able to give exhaustive answers. Inparticular, the innovative methodologies based on IMUs and sEMG, allow the instrumental quantitative assessment ofbiomechanical risk directly in the field thanks to the fact that the sensors are miniaturized, wearable, easily transportableand based on “wireless” transmission of data acquired on the worker who performs the task. These aspects facilitatedata recording, allowing accurate signal acquisition even in unfavorable environments and in work situations where theworker interacts with a cobot or uses an exoskeleton. Previous studies have involved studies of non-fatiguing lifts, wherethe movement and relative risk of single repetitions of lifting were studied. Currently, we wonder what happens when thework activity becomes fatiguing and whether it is still possible to use these methods to classify risk. In addition, anotherunexplored question concerns the presence of workers who continue to perform work activity during the first phase ofonset of musculoskeletal disorders: can the risk to which these workers are exposed be considered the same as thatinvolving workers without pain? To answer these questions, we conducted an experimental campaign at the Universityof Birmingham in collaboration with Roma Tre University and INAIL in which subjects with and without back disordersperformed fatiguing lifts of 15 minutes in three risk levels determined by three different lifting frequencies. We studiedtrunk muscle activity in terms of muscle coactivation of the trunk flexor and extensor muscles. The results show howcoactivation can classify risk during manual load lifting activities by distinguishing not only the level of risk but alsothe presence or absence of back disorders. These results suggest that the use of electromyographic features to assess thebiomechanical risk associated with work activities can also be used in the presence of fatiguing lifting also to distinguishthe risk in case of subjects with back pain. This methodology could be used to monitor fatigue and extend the possibilitiesoffered by currently available instrumental-based approaches.

Biomechanical risk in fatiguing frequency-dependent lifting activities: muscle coactivation in people with and without low back pain

Musculoskeletal diseases and disorders from biomechanical overload are very common among workers. In Italy in 2019, occupational diseases of the osteomuscular system and connective tissue accounted for 66% of the total number of diseases reported to INAIL. Many factors can contribute to the establishment of a condition of biomechanical overload and therefore to the onset of work-related musculoskeletal disorders (WMSDs). Among these, work-related low-back disorders (WLBDs), caused mainly by handling heavy loads, are very common. In recent years, several methods have been developed to assess the risk of biomechanical overload, included in several international standards (ISO-11228, ISO-11226, ISO/TR 12295 and 12296) aimed at identifying high-risk work activities and assessing the effectiveness of ergonomic interventions. Among the best known, with regard to the manual lifting of heavy loads, there is the Revised NIOSH Lifting Equation that, while presenting many advantages (cost-effectiveness, non-invasiveness, speed of application ...) at the same time also has limitations concerning mainly the high subjectivity (subject of scientific debate) and the impossibility of these methods to assess all work tasks. From these premises, it is clear the usefulness of being able to use new quantitative risk assessment methodologies, objectifiable and repeatable, which provide for the possibility of assessing the risk from biomechanical overload even in modern working scenarios where the use of exoskeletons by workers and the sharing of working space with cobots is becoming increasingly widespread. In fact, the methods currently used are incomplete and ineffective in assessing the real impact that these technologies have on the health and safety of workers in Industry 4.0. Recent studies (some of which we were involved in) have introduced the possibilities offered by optoelectronic systems, inertial sensors (IMUs) and surface electromyography (sEMG), to integrate the most widely used observational methodologies. These modern technologies, evaluating how a subject moves his joints and uses his muscles during the execution of a work task, can integrate the observational methods, quantify the elements that characterize the risk minimizing the evaluation errors caused by individual subjectivity and allow to carry out the assessment of biomechanical risk even in those areas where the currently most widespread methodologies are not able to give exhaustive answers. In particular, the innovative methodologies based on IMUs and sEMG, allow the instrumental quantitative assessment of biomechanical risk directly in the field thanks to the fact that the sensors are miniaturized, wearable, easily transportable and based on "wireless" transmission of data acquired on the worker who performs the task. These aspects facilitate data recording, allowing accurate signal acquisition even in unfavorable environments and in work situations where the worker interacts with a cobot or uses an exoskeleton. Previous studies have involved studies of non-fatiguing lifts, where the movement and relative risk of single repetitions of lifting were studied. Currently, we wonder what happens when the work activity becomes fatiguing and whether it is still possible to use these methods to classify risk. In addition, another unexplored question concerns the presence of workers who continue to perform work activity during the first phase of onset of musculoskeletal disorders: can the risk to which these workers are exposed be considered the same as that involving workers without pain? To answer these questions, we conducted an experimental campaign at the University of Birmingham in collaboration with Roma Tre University and INAIL in which subjects with and without back disorders performed fatiguing lifts of 15 minutes in three risk levels determined by three different lifting frequencies. We studied trunk muscle activity in terms of muscle coactivation of the trunk flexor and extensor muscles. The results show how coactivation can classify risk during manual load lifting activities by distinguishing not only the level of risk but also the presence or absence of back disorders. These results suggest that the use of electromyographic features to assess the biomechanical risk associated with work activities can also be used in the presence of fatiguing lifting also to distinguish the risk in case of subjects with back pain. This methodology could be used to monitor fatigue and extend the possibilities offered by currently available instrumental-based approaches.

Investigation on flow around and through a hygroscopic porous cylinder with consideration of compressibility of moist air

In order to better understand the influence of the physical conditions, such as high temperature, high humidity, and high speed, on porous media in coastal engineering, a compressible, viscous, unsteady flow around and through a hygroscopic porous circular cylinder was discussed in this paper. The effects of the hygroscopicity, the Mach number, and the Darcy number on the flow structure, temperature field, and water content of the porous cylinder are evaluated in detail. The results of numerical simulations show significant effects of compressibility of moist air on the lift and drag of the cylinder. With an increase in the Mach number, the frequency of vortex shedding argument and dimensionless lift and drag of the porous cylindrical surface decrease. Nevertheless, the effect of the Mach number on the magnitude of the vorticity and distribution of temperature is negligible. In our simulation, we also found that an increase in the Darcy number significantly weakens the magnitude of the vorticity and the amplitude of lift and drag of the cylinder. Moreover, the absorption of the porous cylinder may also have a weak effect on accelerating vortex shedding. Considering the high temperature, high humidity, and high speed of the coastal environment, this paper has some significance for the study of wind erosion.