• Journal of the Korean Society of Physical Medicine
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• v.16 no.4
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• pp.95-102
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• 2021

PURPOSE: This study examined the muscle activity of the abdominal muscle when lifting with abdominal hollowing with visual feedback and lifting with a pelvic compression belt. This study suggests how to lift an object safely in the workplace for people who bend their backs repeatedly. METHODS: The study was conducted on healthy men in their 20s and 30s. When lifting a 7kg object, lifting with abdominal hollowing with visual feedback, and lifting an object with a pelvic compression belt were performed three times in random order. The muscle activities were measured rectus abdominis (RA), external oblique (EO), internal oblique/transverse abdominis (IO/TrA) muscles, and abdominal hollowing exercises, and box lifting exercises were carried out in advance before the experiment. One-way ANOVA was used to compare muscle activities, and a Tukey HSD was used for post-analysis. The level of significance was set to .05. RESULTS: According to the study, there was no significant difference in muscle activity of the RA muscle depending on the lifting method (p > .05). There were significant differences between the EO and IO/TrA muscle (p < .05). The IO/TrA muscle activity showed the largest increase in lifting an abdominal hollowing with visual feedback (p < .05). The EO muscle activity increased in pelvic compression belt lifting (p < .05). The muscle activity was increased in RA, but there was no significant difference (p < .05). CONCLUSION: Abdominal hollowing lifting with visual feedback increases the muscle activity of the IO/TrA muscle, which is higher than normal, and affects the core stability of the body.

• Journal of Korean Physical Therapy Science
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• v.31 no.2
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• pp.30-40
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• 2024

Background: The purpose of this study is to identify the difference in muscle activity and muscle contraction onset time according to a LLD and object weight When subjects performed a lifting task. Design: Repeated measure design Methods: 15 male adults participated in this study. When subjects performed a lifting task, we measured a difference of muscle activity and muscle contraction onset time in the rectus abdominis(RA), the erector spinae(ES), and the rectus femoris(RF) between both legs using the surface electromyogram (Telemyo DTS, Noraxon Inc., USA). When subjects performed a lifting task, the weight of the object was set to 0% kg, 10% kg, and 20% kg of the subject's body weight, excluding the weight of the box. Results: The difference in muscle activity in the RA, the ES, and the RF between both legs when lifting an object was larger in LLD condition than in non-LLD condition(p<0.05). In all of muscles, the difference of contraction onset time was generally increased as the object's weight increased. Specially, the difference in muscle contraction onset time in the RA, the ES between both legs was larger in the LLD condition than in the non-LLD condition(p<0.05). Conclusion: This study suggests that LLD affects the muscle activity and muscle contraction onset time during lifting objects. It can be used as data to prevent joint damage and muscle due to the LLD during work and movements of daily living.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.19 no.1
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• pp.25-29
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• 2009

The purpose of this study was to investigate the effect of two different lifting posture on the plantar foot pressure, force and COP(center of pressure) trajectory path during object lifting. Fourteen healthy adults who had no musculoskeletal disorders were instructed to lift with two postures(stoop and squat) and two object weights(empty box and 10 kg box). Plantar foot pressures, forces and COP trajectory path were recorded by the F-mat system(Tekscan, Boston, USA) during object lifting with barefoot. Plantar foot surface was defined as seven regions for pressure measurement; two toe regions, three forefoot regions, one midfoot region and one heel region. Paired t-test was used to compare the outcomes of peak pressure and maximum force with different two lifting postures and two object weights. Plantar peak pressure and maximum force under hallux was significantly greater in squat posture than stoop posture during the two different boxes lifting(p<.05). During the empty box lifting, maximum force under lessor toes was significantly less and plantar peak pressure under second metatarsal region was significantly greater in squat than stoop(p<.05). Maximum force under heel was significantly less in squat than stoop posture during 10kg box lifting(p<.05). Finally, COP trajectory path was significantly greater in squat than stoop(p<.05). These findings confirm that there are significantly change in the structure and function of the foot during the object lifting with different posture. Future studies should focus on the contribution of both structural and functional change to the development of common foot problems in adults.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.3
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• pp.223-228
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• 2015

This paper analyses the torque characteristics of the shoulder and elbow joints of a humanoid robot arm that is useful for an object lifting and transferring task instead of human beings. For the purpose, some typical human lifting behaviors are considered, and various simulations for lifting and transferring an object have been performed by employing a humanoid robot arm having a simple configuration of shoulder and elbow joints. Through the simulation, it is shown that the torque patterns and ranges of the shoulder and elbow joints required for such a humanoid lifting and transferring task can be found earlier in the design of a humanoid robot arm. As a result, this effort is useful for us to design an effective robot arm.

• Journal of the Korea Society of Computer and Information
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• v.23 no.7
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• pp.49-56
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• 2018

Virtual object weight perception is an important topic, as it heightens the believability of object manipulation in immersive virtual environments. Although weight perception can be achieved using haptic interfaces, their technical complexity makes them difficult to apply in immersive virtual environments. In this study, we present a visual pseudo-haptic feedback system that simulates and depicts the weights of virtual objects, the effect of which is weight perception. The proposed method recognizes grasping and manipulating hand motions using computer vision-based tracking methods, visualizing a Force Arrow to indicate the current lifting forces and its difference from the standard lifting force. With the proposed Force Arrow method, a user can more accurately perceive the logical and unidirectional weight and therefore control the force used to lift a virtual object. In this paper, we investigate the potential of the proposed method in discriminating between different weights of virtual objects.

• Journal of the Korean Society of Safety
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• v.12 no.4
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• pp.209-213
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• 1997

Manual lifting techniques are commonly defined in terms of the postures adopted at the start of the lift. Quantitative definition is problematic, however, because the absolute joint angles adopted to lift an object are influenced by task parameters, such as the initial height of the load. The main objective of this study is to investigate the grip strength of the both hands at the initial lifting points. The survey is conducted by measuring the compression force, anthropometric data and grip strength at the lifting postures for the subjects(n=50) who is assigned to their job as usual. The experiment is peformed at the four lifting postures which involving the combination of two horizontal factors(H1 : 35 cm, H2 : 55 cm) and two vertical factors(V1 : 20~80 cm, V2 : 47~102 cm). The analysis result of lifting posture indicated that each H1-V1, H2-V1 combinations are about 60$^{\circ}$ and each H1-V2, H2-V2 combinations are about $30^{\circ}$. There are significant differences on grip strength between $60^{\circ}$ and $30^{\circ}$ stooped posture. The results of this study can be provided a method defining lifting postures at the minimum grip strength. Also, it is eliminated a hazard of the injuries which are cumulative trauma disorders(CTDs) and back pain, increased a productivity and improved a welfare of workers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4629-4635
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• 2012

This study was aimed at the relationship between peak EMG amplitude on low back muscles acting on L5/S1 and load center of gravity, trunk lateral bending while lifting an object. Musculoskeletal disorders including low back pain can occur even when handling heavy objects only once as well as when doing non-heavy materials repeatedly. 11 male subjects with average 23 age were required to lift a 15.8kg object symmetrically three times. Peak EMG amplitudes on 6 muscles related with L5/S1 were recorded and analyzed. The lifting conditions consisted of lifting symmetric load with no trunk lateral bending, asymmetric load with no trunk lateral bending, and asymmetric load with trunk lateral bending to the load center of gravity within an object. The results showed that peak EMG amplitude on back muscles contralateral to load center of gravity was observed greater in comparison with the symmetric load. Also, in case of lifting asymmetric load the posture with trunk lateral bending increased peak EMG amplitude on muscles contralateral to load center of gravity more than with no trunk lateral bending. This research can be used as one administrative intervention in order to reduce the low back pain incidence with suggesting workers that they keep the trunk not bending to load center of gravity if possible when lifting a heavy asymmetric object.

• The Journal of Korea Robotics Society
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• v.10 no.3
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• pp.139-145
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• 2015

This paper proposed a method of cooperative control of three mobile robots for carrying an object placed on a floor together. Each robot moves to the object independently from its location to a pre-designated location for grasping the object stably. After grasping the common object, the coordination among the robots has been achieved by a master-slave mode. That is, a trajectory planning has been done for the master robot and the distances form the master robot to the two slave robots have been kept constant during the carrying operation. The localization for mobile robots has been implemented using the encoder data and inverse kinematics since the whole system does not have the slippage as much as a single mobile robot. Before the carrying operation, the lifting operations are implemented using the manipulators attached on the top of the mobile robots cooperatively. The real cooperative lifting and carrying operations are implanted to show the feasibility of the master-slave mode control based on the kinematics using the mobile manipulators developed for this research.

• Journal of Korean Physical Therapy Science
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• v.17 no.3_4
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• pp.29-39
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• 2010

Purpose: The purpose of this study was to examine the effect of foot position and lifting an object on muscle activity and foot pressure during sit to stand(STS) in hemiparetic patients. Methods: Fourteen patients participated in this study. Surface electromyography was used to collect muscle activity and foot pressure measurement system was used to analyze foot pressure in hemiparetic side. Three different foot position was assumed(anterior, neutral, posterior) in hemiparetic side. The repeated two-way analysis of variance and multiple comparisons were conducted to determine statistical significance with a significance level of 0.05. Results: The results were as follows. 1) Lower extremity muscle activity was significantly higher(p<0.05) in biceps femoris and tibialis anterior muscle during STS without holding an object. With changing positions of the affected foot, muscle activity was significantly increased (p<0.05) in vastus medialis and lateral gastrocnemius when the foot was positioned in posterior. 2) There was no significant difference(p>0.05) in foot pressure during STS with object holding and foot positioning. Conclusion: Muscle activity showed a significant increase when the foot was positioned in posterior in comparison to the muscle activity when the foot was in neutral or anterior position.

• Journal of the Korean Society of Physical Medicine
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• v.9 no.3
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• pp.243-248
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• 2014

PURPOSE: This study was aim to the change of muscle activities of lower extremity and waist during lifting a small object on the floor according to different foot position of women in their twenties wearing a skirt. METHODS: 9 women in their twenties wearing a skirt were selected and were measured the muscle activities of medial gastrocnemius (MG), tibialis anterior (TA), vastus lateralis (VL) and iliocostalis (IC) when they lifted a small object on the floor. The two different foot position employed were "both feet posed straight side by side" (condition 1) and "both feet posed diagonally to 45 degree" (condition 2) used. The order of feet position was selected randomly and the subject took a rest for 30 min between tests to prevent muscle fatigue. We calculated the mean and standard deviation of muscle activities and used Mann-Whitney U test to compare the difference between the two foot positions with SPSS(IBM Korea) RESULTS: The muscle activity of condition 2 was greater than that of condition 1 in right side of TA, VL, and IC and left side of TA, VL, MG and IC. The right side of TA, VL and left side VL were significant difference between condition 1 and condition 2(p<.05). CONCLUSION: We suggest "both feet posed straight side by side" position is better if a woman wearing a skirt lift the small object and it will help prevent the low back and lower limb problems in the future.