Maximum Acceptable Weight Research Articles

Pengaruh faktor pengali asimetri terhadap kapasitas beban angkat perempuan Indonesia

Manual material handling can improve occupational diseases such as low back pain and musculoskeletal disorders. In an attempt to reduce the risk of injury as a result of such work, NIOSH published the recommended weight limit (RWL) equation. The RWL formulation was made with Europeans and Americans, so this research was conducted to see the suitability of the RWL formulation for Asians, especially Indonesians. The participants of this study were 30 Indonesian women students. The independent variable in this research is the asymmetry multiplier. The participants perform asymmetric lifting in 0, 30, 60, and 90 degrees with the frequency of 1 lift/min in a 30-minute duration. Other multiplier factors such as the vertical multiplier, distance multiplier, and coupling multiplier are made to have a value of 1. The weight of the load lifted by the respondent is adjusted to the maximum load that each respondent can lift comfortably, which is usually called the maximum acceptable weight of lift (MAWL). The heart rate data used for analysis is the heart rate in the last five minutes. In addition, respondents also filled out the Borg RPE scale. The results of this study were that the heart rate increased from an average resting heart rate of 83.12 beats/minute to 90.6 beats/minute. The statistical test results showed that there was no significant effect between asymmetry lifting tasks on heart rate, energy expenditure, and the Borg's Scale RPE (α = 0,05). Energy expenditure in this study is still below the threshold set by NIOSH. From this study, the predicted AM equation of physiological for Indonesian (energy expenditure) is AM = 1 - (0,0024A) and the predicted AM equation of RPE is AM = 1 - (0,0029A).

Predicting the load constant of the revised NIOSH lifting equation based on demographics

Manual materials handling (MMH) and lifting activities have been identified as risk factors for lower back pain (LBP). Of the many tools available to analyse and design lifting tasks, the revised NIOSH lifting equation (RNLE) is perhaps the most widely used. However, the equation is based on data primarily from the West. To make the model universally applicable, the effect of worker characteristics like age, gender, weight and anthropometry on maximum acceptable weight limits (MAWLs) was studied. A psychophysical methodology was adopted to arrive at the MAWLs. In total, 58 industrial workers (30 men and 28 women) participated in the study. Based on the observations of the study, an equation was developed that would allow the RNLE load constant to be modified for different populations based on simple anthropometric data. The load constant for the Indian population was found to be comparable to the RNLE recommendations

Ergonomics Evaluation of Manual Lifting Task on Biomechanical Stress in Symmetric Posture

Introduction: Manual lifting operations continue to play a key role in the industrial and service sectors, inflicting physical strain on the musculoskeletal system, despite advances in automation. As a result, an experiment is carried out to assess the impact of two lifting task parameters; weight and height, based on the estimation of subjective responses and biomechanical loading, while lifting the weight symmetrically in the sagittal plane. Also to recommend the safe limit for manual lifting tasks. Methods: Twelve volunteer male students in the age group of 21 to 26 years performed lifting tasks from floor to 5 different heights (below the knee to ear level), with 5 different weights (10 to 20 kg) using free-style lifting techniques. The load pan with no handle was used for lifting weight, which is typically adopted in the Indian building construction field. The subjective estimate was obtained using workload assessment by body discomfort chart. The biomechanical loading (loading rate) for each lifted weight and height was collected using a force platform. Results: The results showed that heavier weights produced higher stresses than lower weights. The loading rate was found to be almost similar at waist or knee level. The loading rate was observed to be linearly increasing after waist level. The overall workload rating seems to be a good correlate with the mean loading rate to some extent. Conclusion: It is proposed to keep the maximum acceptable lifting weight from floor to knee, up to the ear level is 15 kg, to prevent any musculoskeletal or chronic injury.

Automated Workers’ Ergonomic Risk Assessment in Manual Material Handling Using sEMG Wearable Sensors and Machine Learning

Manual material handling tasks have the potential to be highly unsafe from an ergonomic viewpoint. Safety inspections to monitor body postures can help mitigate ergonomic risks of material handling. However, the real effect of awkward muscle movements, strains, and excessive forces that may result in an injury may not be identified by external cues. This paper evaluates the ability of surface electromyogram (EMG)-based systems together with machine learning algorithms to automatically detect body movements that may harm muscles in material handling. The analysis utilized a lifting equation developed by the U.S. National Institute for Occupational Safety and Health (NIOSH). This equation determines a Recommended Weight Limit, which suggests the maximum acceptable weight that a healthy worker can lift and carry, as well as a Lifting Index value to assess the risk extent. Four different machine learning models, namely Decision Tree, Support Vector Machine, K-Nearest Neighbor, and Random Forest are developed to classify the risk assessments calculated based on the NIOSH lifting equation. The sensitivity of the models to various parameters is also evaluated to find the best performance using each algorithm. Results indicate that Decision Tree models have the potential to predict the risk level with close to 99.35% accuracy.

Uso de carretilla de acero en transporte de carga para prevención de trastornos musculo-esqueléticos en los trabajadores de despacho de la empresa Ecovasti S.A.

Introduction. Manual lifting and carrying of loads that are equal to or greater than 25 kg are considered high ergonomic risk for causing musculoskeletal disorders in any activity where there is no load sharing or mechanical assistance. Objective. This research applies the use of a steel mask as a mechanical aid to attenuate musculoskeletal disorders in the workers of the company Ecovasti S.A. who lift and move the jars of alcoholic beverages in the delivery of the product to the customers. Methodology. A preliminary analysis of the lifting and moving of loads in the manual dispatch of alcoholic beverage jars was made using Snook and Ciriello tables to find the maximum acceptable weight and the level of ergonomic risk, then the key indicators of pull and push method (KIM PP) was applied to demonstrate the ergonomic improvement by implementing the help of a mobile steel forklift. Results. The preliminary study with the Snook and Ciriello tables indicates a maximum load handling weight for lowering, lifting, transporting and dragging: 11.9 kg; 7.79 kg; 16.43 kg and 25.67 kg respectively, considering male gender, with a protection percentage of 90%, maximum distance traveled of 8 m, load weight of 23 kg per jug of alcoholic beverage, average transfer height of 0.8 m, with a frequency of 15 transfers per hour. The result of the application of the ergonomic improvement with the use of the key indicators of pull and push method (KIM PP) was a value of 1, which corresponds to a low ergonomic risk with a low probability of physical overload. Conclusion. The result of the application of a steel trolley for the manual transport of alcoholic beverage jugs in the dispensing to customers attenuates the level of ergonomic risk to low risk values and could help prevent musculoskeletal disorders.

Effects of Lifting Method, Safety Shoe Type, and Lifting Frequency on Maximum Acceptable Weight of Lift, Physiological Responses, and Safety Shoes Discomfort Rating.

This study aimed to investigate the physical effects of precision lifting tasks on the maximal acceptable weight of a lift (i.e., psychophysiological lifting capacity where the workers adjust the lifting weight in order to work without any fatigue or strain at the end of the work while wearing common safety shoe types). Additionally, the physical difference between the precise and non-precise lifting conditions associated with wearing safety shoes were assessed by respiration responses and shoe discomfort ratings. To achieve the objective of the study, ten healthy male workers were selected by age (between 25 to 35 years old). Their anthropometric characteristics, including knuckle height, knee height, and body mass index (BMI), were measured. A three-way repeated measures design with three independent variables was used; the variables included—the (1) lifting method (precise and non-precise), (2) lifting frequency (1 and 4 lifts per min), and (3) safety shoe type (light-duty, medium-duty, and heavy-duty). The physiological response variables and one of the subjective factors of this study were—(1) respiration responses, and (2) shoe discomfort rating, respectively. The data were analyzed using the Mauchly’s test of sphericity, Shapiro–Wilk normality test, and analysis of variance (ANOVA). The results showed that the use of heavy-duty safety shoes typically increased the shoe discomfort rating under precise lifting methods. Additionally, the lifting frequency was determined to be one of the main factors affecting respiratory responses and shoe discomfort rating. This study also found that respiration responses rose on four lifts per min as compared to 1 lift per min, regardless of the lifting method type. This study indicated that the replacement of some types of ordinary safety shoes used in some workplaces with those selected appropriately might significantly reduce the rating effort required to lift objects or tools. However, the benefits should be carefully evaluated before replacing the safety shoes.

Using Electroencephalography (EEG) Power Responses to Investigate the Effects of Ambient Oxygen Content, Safety Shoe Type, and Lifting Frequency on the Worker's Activities.

Objective The study assesses the changes in electroencephalography (EEG) power spectral density of individuals in hypoxia when wearing a different type of safety shoes under different lifting frequencies. It also assesses the EEG response behavior induced via the process of lifting loads related to these variables. Methods The study was conducted in two consecutive phases: training and acclimatization phase and experimental lifting phase. Ten male college students participated in this study. A four-way repeated measures design was used in this research with independent variables: ambient oxygen content (“15%, 18%, and 20%”), safety shoes type (“light-duty, medium-duty, and heavy-duty”), lifting frequency (“1 and 4 lifts/min”), and replication (“first and second”). And the dependent variables were alpha, theta, beta, gamma, θ/α, θ/β, α/β, β/α, (θ + α)/β, and (θ + α)/(α + β). The participant was allowed to determine his maximum acceptable weight of lift (MAWL) in fifteen minutes of lifting using psychophysically technique. Then, he continued lifting the MAWL for another five minutes, where all the data were collected. Results Results showed that the EEG responses at lower levels of the independent variables were significantly high than at higher levels; except for oxygen content, the EEG responses at lower levels were considerably lower than at a higher level. It also showed that an upsurge in the physical demand increased lifting frequency and replication and caused decreasing in alpha power, theta/beta, alpha/beta, (theta + alpha)/beta, (theta + alpha)/(alpha + beta) and increasing in the theta power and the gamma power. Furthermore, several interactions among independent variables had significant effects on the EEG responses. Conclusion The EEG implementation for the investigation of neural responses to physical demands allows for the possibility of newer nontraditional and faster methods of human performance monitoring. These methods provide effective and reliable results as compared to other traditional methods. This study will safeguard the physical capabilities and possible health risks of industrial workers. And the applications of these tasks can occur in almost all working environments (factories, warehouses, airports, building sites, farms, hospitals, offices, etc.) that are at high altitudes. It can include lifting boxes at a packaging line, handling construction materials, handling patients in hospitals, and cleaning.

Key Factors Influencing Multimodal Transportation of Natural Block Rubber in Thailand

Thailand is the world’s largest natural rubbers exporter. The major type of natural rubbers exported is block rubber. Currently, the transportation of natural rubbers in Thailand depends mainly on truck mode because of the convenience and extensive network of roads. However, Thailand confronts road transportation limitations including maximum acceptable weight, traffic congestion and high fuel prices. Dealing with these problems, the multimodal connection from roads to container yards (CY) and ports is expected to decrease logistics cost, and increase various opportunities to trade with neighbouring countries. This paper, thus, aims at examining key factors influencing the use of multimodal transportation utilizing the exploratory factor analysis (EFA). The principal components analysis (PCA) method, together with the eigenvalue over 1, factor loading of 0.40, and varimax rotation method, extracted five key factors with a total of 20 associated attributes, which are the Multimodal Operation, Service Operation, Multimodal Service Provider, Market Consideration, and Road Constraints factors. The result also pinpoints the capacity of container yard (CY) or port, accessibility to container yard (CY) or port, documentation process, logistics cost, adequacy of a multimode service provider, and law enforcement on truck driving hours, as crucial attributes in planning for multimodal transportation. This paper can be used as a guideline for a feasibility study of multimodal transportation of natural block rubber in Thailand.

Effect of Ambient Oxygen Content, Safety Shoe Type, and Lifting Frequency on Subject's MAWL and Physiological Responses.

Objective: The purpose of this study was to evaluate the lifting capabilities of individuals in hypoxia when they wear different types of safety shoes and to investigate the behavior of the physiological responses induced by the lifting process associated with those variables. Methods: An experimental design was used, based on two sessions. The first was training and acclimatization session, then an experimental lifting phase. A total of ten male students of King Saud University were recruited in the study. A four-way repeated measures design, with four independent variables and six dependent variables, was used in this research. The independent variables that were studied in the experimental lifting phase were: ambient oxygen content (15%, 18%, and 21%), safety shoes type (light-duty, medium-duty, and heavy-duty), lifting frequency (1 and 4 lifts/min), and replication (first and second trials). The dependent variables were also: maximum acceptable weights lifting using the psychophysical technique, heart rate (HR), electromyography (EMG) of (biceps brachii, trapezius, anterior deltoid, and erector spinae), safety shoes discomfort rating, rating of perceived exertion, and ambient oxygen discomfort rating. Results: The maximum acceptable weights lifting that were selected by participants at lower levels of the independent variables (ambient oxygen content 21%, lifting frequency 1 lift/min, and first replication) were significantly higher than at high levels of the independent variables (ambient oxygen content 15%, lifting frequency 4 lift/min, and second replication). Several interaction effects were also significant. Conclusions: It provides evidence that the ambient oxygen content increases the intensity of workload in lifting tasks. It showed that oxygen content affects the psychophysical selection of maximum acceptable weights lifting and the physiological responses represented in muscular activities and heart rate. It suggests that ambient oxygen content must be considered along with the type of safety shoes worn when the lifting task at altitudes occurs.

Statistical prediction of load carriage mode and magnitude from inertial sensor derived gait kinematics

Load carriage induces systematic alterations in gait patterns and pelvic-thoracic coordination. Leveraging this information, the objective of this study was to develop and assess a statistical prediction algorithm that uses body-worn inertial sensor data for classifying load carrying modes and load levels. Nine men participated in an experiment carrying a hand load in four modes: one-handed right and left carry, and two-handed side and anterior carry, each at 50% and 75% of the participant's maximum acceptable weight of carry, and a no-load reference condition. Twelve gait parameters calculated from inertial sensor data for each gait cycle, including gait phase durations, torso and pelvis postural sway, and thoracic-pelvic coordination were used as predictors in a two-stage hierarchical random forest classification model with Bayesian inference. The model correctly classified 96.9% of the carrying modes and 93.1% of the load levels. Coronal thoracic-pelvic coordination and pelvis postural sway were the most relevant predictors although their relative importance differed between carrying mode and load level prediction models. This study presents an algorithmic framework for combining inertial sensing with statistical prediction with potential use for quantifying physical exposures from load carriage.

Are psychophysically chosen lifting loads based on joint kinetics?

Tables of maximal acceptable weight limits (MAWL) are used to select safe lifting loads and help reduce workplace injuries. However, their subjective basis provides little information on the underlying load selection rationale, and few studies have examined MAWLs in relation to full-body joint demands. Therefore, link-segment biomechanical modeling was applied for 18 participants during three sagittal 4.3 lifts/minute tasks at chosen MAWL levels. Each lift produced unique kinematics, kinetics, MAWL loads and most highly stressed joints. Lifting from the lowest starting position most heavily challenged the L5/S1 joint, whereas more upright starting postures stressed the shoulder. Lifting loads above and below MAWL level demonstrated consistent joint loading patterns. The normalized peak moments of the highest stressed joint were similar across the lifts at ∼70–75% of the joint maximum. Our results suggest that MAWLs may be chosen based on perception of the most stressed joint for the specific lift.

Influence of age on lifting capacity among manual materials handlers.

Recommended weight limit for manual materials handlers has to be decided based on the individual characteristics of the person and age is one of the major variable affecting maximal lifting capacity. But there is limited information on pattern of change in lifting capacity with age. To determine the influence of age on the maximum acceptable weight of lift among manual materials handlers. Two hundred and seventeen male construction workers were grouped into four age quotas- 19-28, 29-38, 39-48 and 49-58 years. Lifting capacity was determined using progressive isoinertial lifting evaluation, adopting semi-squat technique of lifting at two levels: waist and shoulder. A statistically significant increase in the maximum acceptable weight was observed from first to second age group followed by a gradual decline. The percentage of decline from second to third age group was 11.89% and 14.34% and from third to fourth age group was 5.60% and 19.90% for waist and shoulder level respectively. Pattern of change in lifting capacity with age among manual materials handlers has been investigated in this study. Lifting capacity was found to be the greatest in 29-38 year age group, therefore prescribing recommended weight limit uniformly for all the workers may not be the best practice.

Pediatric Donor-Recipient Size Matching - Seeing is Believing, Or is it?

Size matching in pediatric heart transplant (PHTx) remains subjective and weight based, starting at listing, when a maximum acceptable donor weight is entered into UNET. We aimed to develop a process using a library of 3D “donors” to derive a recipient specific data driven max acceptable donor weight.

Determining Changes in Electromyography Indices when Measuring Maximum Acceptable Weight of Lift in Iranian Male Students

In spite of the increasing degree of automation in industry, manual material handling (MMH) is still performed in many occupational settings. The aim of the current study was to determine the maximum acceptable weight of lift using psychophysical and electromyography indices. This experimental study was conducted among 15 male students recruited from Tehran University of Medical Sciences. Each participant performed 18 different lifting tasks which involved three lifting frequencies, three lifting heights and two box sizes. Each set of experiments was conducted during the 20 min work period using free-style lifting technique and subjective as well as objective assessment methodologies. SPSS version 18 software was used for descriptive and analytical analyses by Friedman, Wilcoxon and Spearman correlation techniques. The results demonstrated that muscle activity increased with increasing frequency, height of lift and box size (P<0.05). Meanwhile, MAWLs obtained in this study are lower than those in Snook table (P<0.05). In this study, the level of muscle activity in percent MVC in relation to the erector spine muscles in L3 and T9 regions as well as left and right abdominal external oblique muscles were at 38.89%, 27.78%, 11.11% and 5.55% in terms of muscle activity is more than 70% MVC, respectively. The results of Wilcoxon test revealed that for both small and large boxes under all conditions, significant differences were detected between the beginning and end of the test values for MPF of erector spine in L3 and T9 regions, and left and right abdominal external oblique muscles (P<0.05). The results of Spearman correlation test showed that there was a significant relation between the MAWL, RMS and MPF of the muscles in all test conditions (P<0.05). Based on the results of this study, it was concluded if muscle activity is more than 70% of MVC, the values of Snook tables should be revisited. Furthermore, the biomechanical perspective should receive special attention in determining the standards for MMH.

Older females in the workforce – the effects of age on psychophysical estimates of maximum acceptable lifting loads

The number of older workers in the workforce is increasing substantially, and advanced age is associated with factors that could influence musculoskeletal injury risk and work capacity. This study’s goals were to test whether psychophysical estimates of maximum acceptable weight of lift (liftmax) differed between younger and older workers, and to examine potential explanatory factors. Twenty-four female workers (half 50 + years; half 20–32 years) self-adjusted a box’s mass to their perceived liftmax during four lifting tasks. Older workers’ liftmax values were significantly lower (by approximately 24%) than their younger counterparts. There were no age-related differences in resting heart rate, or peak joint angles and final heart rate during the lifting trials. However, the older group demonstrated lower grip strength (by 24%), and lower heart rate reserve during the trials (by 18%). These results question whether current maximum acceptable lifting weights based on psychophysical information are appropriately protective for female workers greater than 50 years of age.Practitioner Summary: This psychophysical study demonstrated that older female workers (aged 50–63 years) selected maximum acceptable lift masses that were (on average) 24% lower than younger workers (aged 20–32 years), which corresponded with lower grip strength and heart rate reserve. Current maximum acceptable lifting weights based on psychophysical information may not protect female workers greater than 50 years of age.

Effect of ripening conditions on the physicochemical and antioxidant properties of tomato (Lycopersicon esculentum Mill.).

This study was conducted to assess the physicochemical changes and overall nutritional implications of greenhouse-grown "TY Megaton" and "Yureka" tomato cultivars under on-vine and postharvest ripening conditions. In the first group, tomatoes were harvested from a vine at the breaker, pink, and red ripening stages and sampled immediately. The second group was harvested at the breaker stage and allowed to ripen under room conditions to the pink and red stages based on color values, similar to the vine-ripened samples. The results of the present study revealed that fresh weight loss was below the maximum acceptable weight loss and firmness was above the minimum limit of marketing after postharvest ripening to the pink and red stages; moreover, this process did not have any deleterious effect on the antioxidant properties or antioxidant activity of the tomatoes. Hence, the results clearly indicate that breaker-stage tomatoes can be postharvest-ripened under room conditions without affecting their marketability and nutritional components.

Effects of Storage Duration on Physicochemical and Antioxidant Properties of Tomato (Lycopersicon esculentum Mill.)

This study explored the physicochemical and nutritional changes associated with storage duration of fresh tomatoes. Fruits of the ‘TY Megaton’ and ‘Yureka’ tomato cultivars were harvested at the pink stage and stored at 12℃ for 20 days. During storage, firmness, weight loss, skin color (Hunter L, a, b, a / b values), soluble solids content (SSC), titratable acidity (TA), pH, antioxidant contents (lycopene, ascorbic acid, and total phenolics) and antioxidant activity were evaluated. Firmness was above the minimum marketable limit and fresh weight loss was below maximum acceptable weight loss after 3 weeks of storage, and no deleterious effect on antioxidant contents or activities were observed. Significant differences in SSC, TA, and pH were seen between varieties, but not between fruits stored for different durations. In both varieties, Hunter a values increased more than five-fold after 8 days of storage; this correlated with a more than four-fold accumulation of lycopene after two weeks of storage. The antioxidant activity of tomatoes was highest at the beginning of the storage period, likely because of the effective DPPH - reducing power of ascorbic acid and total phenolics. Antioxidant activity increased after 12 days of storage because of increasing lycopene content. Hence, this study indicates that pink - stage tomatoes may be stored at 12℃ for up to 3 weeks without affecting marketability or nutritional value.

The effects of arm posture and holding time on holding capability and muscle activity

The aim of this study was to examine the effects of arm posture and holding time on human holding capability and resulting muscle activity. Fifteen healthy young males were recruited as participants. Maximum holding capacity was examined at 0 (degrees of shoulder forward flexion angle)/90 (degrees of elbow angle), 30/120 and 90/180 arm postures. Maximum acceptable weight of holding was evaluated in three arm postures (0/90, 30/120, 90/180) by three holding times (10 s, 20 s, 30 s). The greatest and lowest maximum holding capacity or maximum acceptable weight of holding occurred at 0/90 and 90/180 arm postures, respectively. Maximum acceptable weight of holding decreased with increasing holding time. While holding maximum acceptable weights, the % of maximum voluntary contraction of brachioradialis, biceps brachii and erector spinae ranged from 14 to 44%, from 14 to 53% and from 25 to 36%, respectively.

Assessment of various contributing factors for back pain in children while carrying school bags

It is common today to see school children buckling from weight of their school bags, many children bear the burden of carrying school bags that are to heavy for their body frames, that might end up facing a number of health problems. The objectives were to assess the school bag weight and body weight to get the MASW(maximum acceptable school bag weight) and to investigate contributing factors of back pain felt by children carrying school bags. The study was conducted on a sample of 120 school children from middle class ( i.e. from vi to viii) and on their mothers. Respondents were randomly selected from five government and five private schools of Ludhiana city form the age group of 11-14 years. A pre structured interview schedule was used to get the data to achieve the objectives. Results show that only 54 respondents were following the standard value of MASW, which is >15 per cent of the body weight. Average total time was 46 min to carry school bag and standard deviation was 9.40. It was observed that half of the respondents carrying school bags with one or both strap in one shoulder. Total distance covered by the respondents from home to school and vice versa was 218 meter in 46 minutes.

Obesity-related changes in prolonged repetitive lifting performance

Despite the rising prevalence of obesity, little is known about its moderating effects on injury risk factors, such as fatigue, in occupational settings. This study investigated the effect of obesity, prolonged repetitive lifting and their interaction on lifting performance of 14 participants, 7 obese (mean body mass index (BMI): 33.2 kg m−2) and 7 non-obese (mean BMI: 22.2 kg m−2) subjects. To present a physically challenging task, subjects performed repetitive lifting for 1 h at 120% of their maximum acceptable weight of lift. Generalized linear mixed models were fit to posture and acceleration data. The obese group bent to a ∼10° lower peak trunk sagittal flexion angle, had 17% lower root mean square (RMS) jerk and took 0.8 s longer per lift. Over time, the obese group increased their trunk transverse and sagittal posterior accelerations while the non-obese maintained theirs. Although the majority of lifting variables were unaffected by BMI or its interaction with prolonged lifting duration, the observed differences, combined with a greater upper body mass, necessitate a more cautious use of existing psychophysical lifting limits for individuals who are obese, particularly when fatigued.