Force Exertion Research Articles

Addressing OSH challenges in non-standardized work practices in small-scale FMCG units by introducing context-specific ergonomic pouch/sachet cutting apparatus.

The FMCG manufacturing industry in industrially developing countries operates in a manual or semi-automatic setup, employing a vast labor force. Several non-standardized work activities prevail on the FMCG shop floor and remain prone to safety-related risks involving repetitive motions, forceful exertions, and awkward postures. Among those, the rework of defective pouches/sachets is an unsafe activity of prime concern. It is prone to minor nicks, cuts, and injuries due to inadequate tools being used. It involves sharp cutters/blades and extensive forceful manual hand squeezing, which leads to drudgery and safety concerns. There lies the lack of standardized tools/apparatus for rework activity, and efforts towards its mitigation are required. Current research aims to address occupational safety-related issues in non-standardized rework activity in small-scale FMCG units through an innovative product design approach. An ergo-audit was conducted in eight small-scale FMCG units to identify the prevailing ergonomic stressors and safety concerns. The most critical area of concern, i.e., rework activity, was chosen through card-sorting sessions and discussions held with the stakeholders. An appropriate context-specific apparatus was designed/developed to ensure better safety and occupational health utilizing a systematic product design method involving three phases: initial field survey, design and development, and field trials. The apparatus, which was developed and factory-trialed, was evaluated for productivity improvement and ensuring user compatibility from various human factors' perspectives. In field trials, the developed apparatus was found effective in mitigating safety concerns and various ergonomic stressors associated with FMCG rework.

Analisis Postur Kerja Pada Bagian Packing Menggunakan Metode ManTRA Dan REBA

PT. Indonesia Plafon Semesta is a company engaged in manufacturing, this company produces various kinds of PVC ceilings. Problems faced by PT. Indonesia Plafon Semesta is the activity of making PVC ceilings in the packing section, where the activity conditions or workers' posture is not good. When packing by squatting and bending, the position is less ergonomic, resulting in excessive force exertion and the risk of injury. This research aims to determine the level of complaints felt by workers in body parts by identifying them using the Nordic Body Map (NBM), Manual Task Risk Assessment (ManTRA) to determine the level of risk experienced by workers and knowing how many angles are formed. Rapid Entire Body Assessment (REBA) is used to calculate worker posture and provide a score of the worker's proposed posture using Anthropometry. Data processing was carried out using NBM calculations for workers who had the highest score of 51 and the lowest 44. Knowing the level of risk experienced by workers with Mantra protection with the back, forearms, neck and wrists > 15 and the angle formed in the REBA calculation using score 10. Improvement of the proposed posture with Anthropomerti with a TPO calculation of 32.5 cm and JTD cm of 69 by paying attention to the object being worked on with REBA calculation results having a score of 7.

Rate of Force Development During a Handgrip Task Is Correlated with the Post-Impact Ball Speed of the Flat Serve

The aim of the present research was to test the hypothesis that rate of force development (RFD) during a handgrip task of the dominant arm in three different positions is associated with maximal post-impact ball speed of flat serve (PIBS). Altogether 23 elite junior boys (aged 14.84 ± 2.47 years; weight 59.51 ± 13.83 kg; height 170.47 ± 16.34 cm) tennis players participated in the study. To assess the maximal voluntary contraction (MVC) and RFD during the task, four handgrip tests and a serve test were applied to estimate PIBS. Spearman’s rank correlation showed a significant positive correlation between RFD of dominant arm in each three position and PIBS (r = 0.82–0.86; p < 0.001). A very large, significantly positive correlation was also found between MVC of the dominant arm and PIBS (r = 0.88; p < 0.01). The result of the present study indicated that rapid force generation of muscles in the forearm and wrist may probably play a role in the formation of a stable contact point, and it is in connection with PIBS. It is in contrast to the slow maximal force exertion that much rather characterizes the general strength state of players. Therefore, measurement of the RFD during a handgrip task is suggested in the testing session of the flat serve of junior tennis players.

High Prevalence and Impact of Shoulder Pain Among Gym Instructors: A Study on Work-Related Musculoskeletal Disorders

INTRODUCTION :- Gym instructors within the fitness industry play a pivotal role in guiding individuals towards achieving a range of health and fitness goals. In addition to muscular and skeletal health, gym instructors are instrumental in boosting the immune system. Even though they help in maintaining the body gym trainers have a limited knowledge of mechanism of injury, neglecting and repetitive movements of the joint leads to worsening of injury and increase in the pain. Musculoskeletal pain can stem from various sources, including uncommon or repetitive activities that strain muscles, tendons, and ligaments. Additionally, it may result from sudden, jerky movements, falls, fractures, or underlying musculoskeletal conditions. The result of repetitive activities that strain the muscles, tendons and sprain the ligaments. Insufficient recovery time, rapid pace work, repetitive motion patterns, heavy weight lifting, forceful manual exertions, mechanical pressure concentrations or whole body vibrations can lead to development of other musculoskeletal disorders. The impact of a musculoskeletal condition on an individual's quality of life is substantial, extending beyond mere physical discomfort. Such conditions not only affect personal well-being but also impose a considerable financial strain, manifested through compensation payments and lost wages. Instances of sick leave, absenteeism, and even job abandonment contribute to diminished job efficiency,further exacerbating the socioeconomic repercussions of these disorders. METHODOLOGY :- A total of 147 participants were selected on the basis of inclusion and exclusion criteria. A consent form was filled by them and the study and questionnaire was explained to them.Self-made Questionnaire was explained to each gym instructors according to language understood by that person as well as google forms were also made available for their convenience.Each gym instructor completed a self administered questionnaire which included information regarding complaints of current shoulder pain. The total data was collected and was statistically analyzed. CONCLUSION :- The Prevalence of shoulder pain in gym instructors is high (78%). The presence of shoulder pain causes a gym instructors to avoid certain activities due to pain which causes a hindrance in their work related activities.

Optimal robot task scheduling in cluttered environments considering mechanical advantage

Abstract In various industrial robotic applications, the effective traversal of a manipulator amidst obstacles and its ability to reach specific task-points are imperative for the execution of predefined tasks. In certain scenarios, the sequence in which the manipulator reaches these task-points significantly impacts the overall cycle time required for task completion. Moreover, some tasks necessitate significant force exertion at the end-effector. Therefore, establishing an optimal sequence for the task-points reached by the end-effector’s tip is crucial for enhancing robot performance, ensuring collision-free motion and maintaining high-force application at the end-effector’s tip. To maximize the manipulator’s manipulability, which serves as a performance index for assessing its force capability, we aim to establish an optimal collision-free task sequence considering higher mechanical advantage. Three optimization criteria are considered: the cycle time, collision avoidance and the manipulability index. Optimization is accomplished using a genetic algorithm coupled with the Bump-Surface concept for collision avoidance. The effectiveness of this approach is confirmed through simulation experiments conducted in 2D and 3D environments with obstacles employing both redundant and non-redundant robots.

Relationship between one-handed push force and subjective rating of force exertion.

Pushing is a typical workplace activity that may result in musculoskeletal disorders (MSDs). A convenient method of assessing the risk of MSDs is to determine the association between the force applied and the subjective rating of force exertion. This study aimed to determine the relationship between the subjective rating of force exertion and the force applied to both a fixed and a movable handle. It also aimed to confirm that the participants could apply a higher one-handed push force at shoulder height than at elbow height. A one-handed pushing experiment was conducted. In the push-to-scale session, the participants pushed a handle fixed on a rig on four levels on the CR-10 scale. The push force was measured. In the force-rating session, the participants rated their force exertions when pushing a movable handle with metal blocks suspended on the two sides. The subjective ratings on the CR-10 were recorded. The one-handed push force at shoulder height was significantly higher than that at elbow height. More effort was needed to push on a movable handle than a fixed one. Two regression models were established to describe the relationship between the push force and the subjective ratings of pushing for each of the fixed and movable handles, respectively. The correlation coefficient results showed that these models are adequate to describe the relationship between the one-handed push force and the ratings of the CR-10 scale. Participants applied a higher one-handed push force at shoulder height than at elbow height was confirmed. Participants needed more efforts to push the movable handle under the same CR-10 level than the fixed handle. The predictive models developed in this study may be used to estimate the push force for one-handed pushing tasks when assessing the risk of MSDs.

Investigation of musculoskeletal symptoms, work postures, quantification of muscle activity, and estimation of grip/push forces among sonographers

AbstractDue to the physical nature of their work, sonographers are exposed to many musculoskeletal disorder risk factors, including awkward posture, repetitive movements, forceful manual exertion, and static muscle contractions, especially in the upper limbs. The current study is an investigation of musculoskeletal disorders among sonographers, caused by various occupational risk factors via different sonographic scan types. During the first phase of this study, the musculoskeletal symptoms and work postures of 29 subjects were investigated. During the second phase, muscle activity was quantified, and grip/push forces were estimated using the data obtained from 10 volunteer sonographers. 82% of sonographers experienced musculoskeletal symptoms. Based on the final scores and action levels obtained via rapid upper limb assessment, while performing scans of left regions; ergonomic changes and interventions were found necessary, to relieve stress on the sonographer's body. The results of muscular activity per muscle and scan type, showed that the mean muscle activity of the middle deltoid muscle was significantly higher during the right abdominal scan (17.64% maximum voluntary contraction [MVC]), compared to those of thyroid (12.54% MVC) and left abdominal (7.32% MVC) scans. Additionally, mean grip and push forces during both abdominal scans were significantly higher than those during the thyroid scan. Despite an injury risk during all scans, risk factor impact was different among scan types. This groundbreaking study represents the first that captures and measures both grip and push forces simultaneously, which may prove helpful while investigating corrective interventions or optimizing design of sonography robots and ergonomic probes in future studies.

Understanding Musculoskeletal Risks in Retail Workers: An Ergonomic Assessment of Store 24H

Musculoskeletal disorders (MSDs) are prevalent in retail environments, often resulting from repetitive tasks, awkward postures, and prolonged standing. This study examined musculoskeletal discomfort and ergonomic risk factors within the retail environment of convenience stores, focusing on the prevalence of MSDs among employees of Store 24H, Dungun, Terengganu, Malaysia. The assessment began with a job task description, followed by workplace observation and worker input. Utilising a systematic approach, the research integrated two standardized assessment tools; the Cornell Musculoskeletal Questionnaire (CMQ) and the Initial Ergonomic Risk Assessment (ERA) Form Checklist, to identify the discomfort area and ergonomic risk factors associated with job tasks. Three job tasks were identified in the Store 24H environment; operating cash registers, customer service and restocking. The findings indicate a notable prevalence of MSDs associated with the identified high-risk tasks. Repetitive motions, awkward postures, prolonged standing, and forceful exertion were observed as primary ergonomic risk factors for these tasks which contribute to musculoskeletal discomfort in the neck, shoulder, back, hip, and knee. Additionally, forceful exertion and vibration exhibit high risks towards restocking tasks, resulting in restocking as the top contributor towards the MSDs. Hence, the findings highlight the need for advanced ERA and mitigation strategies, including workstation redesign, task rotation, ergonomic training and accessories, to promote employee well-being and reduce the incidence of MSDs among employees of Store 24H. Implementing these measures is essential for promoting the health and well-being of employees, decreasing the occurrence of musculoskeletal disorders, and improving overall safety and productivity in the workplace.

Ergonomic Risk Assessment and Mitigation Strategies for Retail Workers: Insights from a Case Study in Dungun

Manual handling activities contribute to 40% of musculoskeletal disorders (MSDs), leading to long-term discomfort, disability, medical costs, and financial hardships for workers, while employers face lower productivity and compensation costs. An ergonomic assessment was conducted among employees at ABC Hardware in Dungun to identify ergonomic risk factors, determine the likelihood of harm affecting workers' musculoskeletal health, and recommend control measures to improve workers' health and well-being. Utilizing a combination of interviews, observations, and questionnaires based on established ergonomics guidelines, the research highlights the prevalence of MSDs among workers engaged in manual handling tasks, emphasizing the need for ergonomic interventions and awareness to enhance workplace safety and employee well-being. Findings from the ergonomic assessment revealed significant discomfort and risk factors related to awkward postures, repetitive motions, forceful exertion, and static positions. Specific ergonomic issues identified include discomfort in the upper back, thighs, and knees among storekeepers, and neck and lower back pain among warehouse workers. Service desk representatives were found to experience discomfort related to static postures and repetitive motions. The study recommends advanced ergonomic assessments such as Rapid Entire Body Assessment (REBA), Occupational Repetitive Assessment (OCRA), and Rapid Upper Limb Assessment (RULA), along with improvements in ergonomic practices and tools. Implementing job rotation, providing ergonomic equipment, and conducting training on proper lifting techniques are essential to address the identified risks. This research highlights the critical role of ergonomic practices in preventing MSDs and improving overall workplace safety.

Comparative Analysis of the Kinematic Characteristics of Lunge-Style and Squat-Style Jerk Techniques in Elite Weightlifters.

This study aimed to discuss the differences in technical characteristics between the lunge-style and squat-style jerk techniques and to reveal the adaptability of these techniques for individual weightlifters. A total of 52 attempts by 32 male weightlifters were selected, and the video data were digitized manually using the SIMI Motion 7.50 three-dimensional analysis system. The technical characteristics of the lunge split and squat jerk were fundamentally consistent during the pre-squat, force exertion, and inertia ascent phases. The primary differences between the lunge split and squat jerk techniques were observed during the squatting and support phases, including the vertical descent velocity of the barbell at the end of the squat shoulder-locking phase and the stability angles in the sagittal and coronal axes. The vertical velocity of the barbell at the end of the squat shoulder-locking phase was significantly greater in the squat style (-0.41 ± 0.17 vs. -0.88 ± 0.14) compared to the lunge style (t = 6.393, p < 0.05). The stability angle on the sagittal axis at the end of the squat-supporting phase in the lunge style was significantly greater (46.99 ± 3.23 vs. 13.64 ± 0.51) than that of the squat style (t = 45.639, p < 0.05).

Impact of Operative Room Noise on Laparoscopic Performance—A Prospective, Randomized Crossover Trial

IntroductionSurgeons are often exposed to different types of operative room (OR) noise, for instance machine alarms, phone calls, and interacting objects. The aim of this study was to evaluate the effect of OR noise on the surgeons’ laparoscopic performance. MethodsA total of 30 laparoscopic novices participated in this single-center, prospective, randomized cross-over trial after completing a standardized laparoscopic training until reaching proficiency. Afterward, all participants performed four different laparoscopic tasks (peg transfer, circle cutting, balloon resection, suture, and knot) twice, once under noise exposure (intervention group), and once without any noise (control group). Primary endpoints were the force exertion and motion analyses. To assess the psychological workload the NASA task load index score was used. ResultsThe error rates varied and were significantly different between the noise and the control group. More complex tasks like the circle cutting and suture and knot task revealed higher error rates concerning precision (circle cutting: P < 0.01; suture and knot: P < 0.01). In line with increased error rates in the circle cutting task, increased NASA task load index scores were observed in this task (P = 0.03). However, no significant differences were found in force parameters, such as the maximal force exertion (peg transfer: P = 0.43; circle cutting: P = 0.54; balloon resection: P = 0.64; suture and knot: P = 0.63) and the mean force exertion (peg transfer: P = 0.43; circle cutting: P = 0.54; balloon resection: P = 0.64; suture and knot: P = 0.63) between the groups. ConclusionsExposure to normal OR noise led to higher error rates in two of four tasks. This effect could be linked to an increased psychological workload that was present under normal OR noise exposure. However, normal OR noise does not appear to impact surgical novices' laparoscopic task performance regarding applied forces and instrument motion.

Force reflections of auditory and tactile action-effect weighting in motor planning

Most voluntary actions have only few goals, which provides considerable freedom in the selection of action parameters. Recent studies showed that task-irrelevant aspects of the task context influence the motor parameters of the actions in a way which seems to reflect the relative importance of these aspects within the underlying action representation. The present study investigated how the intensity of auditory action-effects affected force exertion patterns in a self-paced action production task. Participants applied force impulses with their index finger on a force-sensitive resistor every three seconds. In four separate conditions, force impulses elicited no sound, or elicited tones with 69, 59 or 49 dB intensity. The results showed that participants applied more force when tone intensity was lower, and when tones were absent. These force differences were also present in the first 60 ms following tone onset, implying that these reflected differences in motor planning. The results are compatible with the notion that actions are represented in terms of their sensory effects, which are weighted differently—presumably to maintain an optimal level of overall auditory and tactile stimulation in the present case. These results hint at the potential usefulness of motor parameters as readouts of action intentions.

Enhance Kinesthetic Experience in Perceptual Learning for Welding Motor Skill Acquisition with Virtual Reality and Robot-based Haptic Guidance.

Welding is an important operation in many industries, including construction and manufacturing, which requires extensive training and practices. Although welding simulators have been used to accommodate welding training, it is still challenging to enable novice trainees to effectively understand the kinesthetic experience of the expert in an egocentric manner, such as the proper way of force exertion in complex welding operations. This study implements a robot-assisted perceptual learning system to transfer the expert welders' experience to trainees, including both the positional and force control actions. A human-subject experiment (N = 30) was performed to understand the motor skill acquisition process. Three conditions (control, robotic positional guidance with force visualization, and force perceptual learning with position visualization) were tested to evaluate the role of robotic guidance in welding motion control and force exertion. The results indicated various benefits related to task completion time and force control accuracy under the robotic guidance. The findings can inspire the design of future welding training systems enabled by external robotic systems.

Reduction in motor error by presenting subthreshold somatosensory information during visuomotor tracking tasks

Weak sensory noise acts on the nervous system and promotes sensory and motor functions. This phenomenon is called stochastic resonance and is expected to be applied for improving biological functions. This study investigated the effect of electrical stimulation on grip force adjustment ability. The coefficient of variation and absolute motor error in grip force was measured during a visuomotor tracking task under different intensities of somatosensory noise. Depending on the style of force exertion, the grip movement used in the visuomotor tracking task consisted of force generation (FG), force relaxation (FR), and constant contraction (Constant) phases. The subthreshold condition resulted in significantly lower coefficient of variation in the Constant phase and motor errors in the FG and Constant phases than the no-noise condition. However, the differences among the other conditions were insignificant. Additionally, we examined the correlation between the motor error in the condition without electrical stimulation and the change in motor error induced by subthreshold electrical stimulation. Significant negative correlations were observed in all FG, FR, and Constant phases. These results indicated that somatosensory noise had a strong effect on subjects with large motor errors and enhanced the grip force adjustment ability. By contrast, subjects with small motor errors had weak improvement in motor control. Although the effect of subthreshold noise varies depending on the individual differences, stochastic resonance is effective in improving motor control ability.

Quantifying Patient Capabilities and Setting the Stage for Future Development: Insights from a Sensor-Augmented Simulated Use Study with Pen Injectors.

While formative and summative usability testing is essential to confirm safe and effective product use, it may not be sufficient to comprehensively understand user capabilities and limitations in device interactions. Therefore, this research aims to quantify user handling forces for different device handling steps of pen injectors through sensor-augmented simulated use studies. The study involved 46 participants who were divided into two groups: a healthy control group and a group of users with dexterity impairments. All participants were instructed to perform simulated handling steps using non-functional dummy devices equipped with force and torque sensors. Each handling step was performed twice: first at what participants considered a comfortable force level and then at their maximum force. The study then analyzed force data to investigate the impact of user characteristics and device geometry on force exertion during the different handling steps. The study demonstrates differences in the perceived comfortable and maximum force levels between the control and patient groups. These force levels decrease slightly with the user's age and level of dexterity impairment. Furthermore, the forces applied by the users are dependent on the geometry of the device and the holding pattern. The results highlight the significance of sensor-augmented simulated use studies as a tool for providing quantitative insights into users' ability to exert force while handling self-injection devices. These data offer comprehensive insights that inform the definition of performance requirements and specifications for injection device design, thereby supporting the advancement of future self-injection devices.

Single-cell topographical profiling of the immune synapse reveals a biomechanical signature of cytotoxicity

Immune cells have intensely physical lifestyles characterized by structural plasticity and force exertion. To investigate whether specific immune functions require stereotyped mechanical outputs, we used super-resolution traction force microscopy to compare the immune synapses formed by cytotoxic T cells with contacts formed by other T cell subsets and by macrophages. T cell synapses were globally compressive, which was fundamentally different from the pulling and pinching associated with macrophage phagocytosis. Spectral decomposition of force exertion patterns from each cell type linked cytotoxicity to compressive strength, local protrusiveness, and the induction of complex, asymmetric topography. These features were validated as cytotoxic drivers by genetic disruption of cytoskeletal regulators, live imaging of synaptic secretion, and in silico analysis of interfacial distortion. Synapse architecture and force exertion were sensitive to target stiffness and size, suggesting that the mechanical potentiation of killing is biophysically adaptive. We conclude that cellular cytotoxicity and, by implication, other effector responses are supported by specialized patterns of efferent force.

1D3-6 Fundamental study on the effects of experiencing hazardous events on postural control and force exertion strategies

1D3-6 Fundamental study on the effects of experiencing hazardous events on postural control and force exertion strategies

Organic-inorganic hybrid piezotronic bipolar junction transistor for pressure sensing

With the rapid development of the Internet of Things (IoTs), wearable sensors are playing an increasingly important role in daily monitoring of personal health and wellness. The signal-to-noise-ratio has become the most critical performance factor to consider. To enhance it, on the one hand, good sensing materials/devices have been employed; on the other hand, signal amplification and noise reduction circuits have been used. However, most of these devices and circuits work in an active sampling mode, requiring frequent data acquisition and hence, entailing high-power consumption. In this scenario, a flexible and wearable event-triggered sensor with embedded signal amplification without an external power supply is of great interest. Here, we report a flexible two-terminal piezotronic n-p-n bipolar junction transistor (PBJT) that acts as an autonomous and highly sensitive, current- and/or voltage-mediated pressure sensor. The PBJT is formed by two back-to-back piezotronic diodes which are defined as emitter-base and collector-base diodes. Upon force exertion on the emitter side, as a result of the piezoelectric effect, the emitter-base diode is forward biased while the collector-base diode is reverse biased. Due to the inherent BJT amplification effect, the PBJT achieves record-high sensitivities of 139.7 kPa-1 (current-based) and 88.66 kPa-1 (voltage-based) in sensing mode. The PBJT also has a fast response time of <110 ms under exertion of dynamic stimuli ranging from a flying butterfly to a gentle finger touch. Therefore, the PBJT advances the state of the art not only in terms of sensitivity but also in regard to being self-driven and autonomous, making it promising for pressure sensing and other IoT applications.

The (Un)Capture of Cappanawalla: Vital Materiality and Collaborative Artistic Emergence

This visual essay recounts a photography excursion that unexpectedly evolved into a transformative artistic encounter on Cappanawalla mountain in rural Ireland. What started as a systematic and detached approach of photographic framing and capture, took on a dramatic shift toward an exertion of unknown forces disrupting the human role as artist-photographer. Various nonhuman actants exerted their vital materiality as thing-power forces and collaborators in the creation of images along Cappanawalla. This experience provoked a radical reframing of artistic creation as a distributive agency of authorship among the vital materiality, in which the human is just one creative actant among many.

A cable‐driven underwater robotic system for delicate manipulation of marine biology samples

AbstractUnderwater robotic systems have the potential to assist and complement humans in dangerous or remote environments, such as in the monitoring, sampling, or manipulation of sensitive underwater species. Here we present the design, modeling, and development of an underwater manipulator (UM) with a lightweight cable‐driven structure that allows for delicate deep‐sea reef sampling. The compact and lightweight design of the UM and gripper decreases the coupling effect between the UM and the underwater vehicle (UV) significantly. The UM and gripper are equipped with force sensors, enabling them for soft and sensitive object manipulation and grasping. The accurate force exertion capabilities of the UM ensure efficient operation in the process of localization and approaching reef samples, such as the corals and sponges. The active force control of the tendon‐driven gripper ensures gentle/delicate grasping, handling, and transporting of the marine samples without damaging their tissues. A complete simulation of the UM is provided for deriving the required specifications of actuators and sensors to be compatible with the UVs with a speed range of 1–4 Knots. The system's performance for accurate trajectory tracking and delicate grasping of two different types of underwater species (a sponge skeleton and a Neptune's necklace seaweed) is verified using a model‐free robust‐adaptive position/force controller.