• 산업경영시스템학회지
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• 제28권3호
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• pp.75-86
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• 2005

To investigate the fatigue characteristic of upper limbs, this study analyzed RMS(root mean square) and MPF(mean power frequency) value between initial and terminal stages of each experiment condition. And the effect of intermittent endurance time was evaluated using the Borg's CR10 value that was measured for the parts of upper limb. According to the results of ANOVA on RMS value, there were significant difference on the %MVC about push, pull, and down force exertion. Particularly the ANOVA of up force exertion was significant difference on shoulder flexion, elbow flexion and rest time as well as %MVC. The results of ANOVA for MPF value were significant difference on the %MVC in regard of the push and up force exertion. In case of up force exertion, MPF value tended to shift low frequency at all of the experiment conditions. According to the analysis of duty cycle, RMS value considerably increased over 50% duty cycle and as the %MVC increased, the duty cycle affected the increase of RMS value. MPF value for up and down force exertion decreased at 33%, 50% and 67% duty cycle for all of %MVC. Borg CR10 value of hand and forearm were below the 3-point to the 40% of endurance time at 30%MVC and to the 20% of endurance time at 50%MVC with the exception of up force exertion. But Borg CR10 values of upper arm and shoulder at up force exertion were more than 3-point to the 20% of endurance time at 30%MVC and in the start point of endurance time at 50%MVC.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.1242-1242
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• 2022

Annually, several construction workers fall ill, are injured, or die due to heat-related exposure. The prevalence of work-related heat illness may rise and become an issue for workers operating in temperate climates, given the increase in frequency and intensity of heatwaves in the US. An increase in temperature negatively impacts physical exertion levels and mental state, thereby increasing the potential of accidents on the job site. To reduce the impact of heat stress on workers, it is critical to develop and implement measures for monitoring physical exertion levels and mental state in hot conditions. For this, limited studies have evaluated the utility of wearable biosensors in measuring physical exertion and mental workload in hot conditions. In addition, most studies focus solely on male participants, with little to no reference to female workers who may be exposed to greater heat stress risk. Therefore, this study aims to develop a process for objective and continuous assessment of worker physical exertion and mental workload using wearable biosensors. Physiological data were collected from eight (four male and four female) participants performing a simulated drilling task at 92oF and about 50% humidity level. After removing signal artifacts from the data using multiple filtering processes, the data was compared to a perceived muscle exertion scale and mental workload scale. Results indicate that biosensors' features can effectively detect the change in worker physical and mental state in hot conditions. Therefore, wearable biosensors provide a feasible and effective opportunity to continuously assess worker physical exertion and mental workload.

• 대한인간공학회지
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• 제22권4호
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• pp.47-57
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• 2003

This study investigated the recruitment patterns of ten trunk muscles in isometric exertion tasks, focused on the functional roles (agonist or antagonist). Twelve male students performed maximum voluntary isometric exertion tasks towards six directions: flexion/extension, left/right lateral bending, and clockwise/counter-clockwise twisting. EMG signals from ten trunk muscles and exertion forces were collected. Normalized EMG (NEMG) values were calculated at 10, 20, 30, 40, 50, 60, 70, 80, and 90 %MVC. The subjects showed a limited capacity in producing twisting moments, approximately 50% of the extension moment, and 70% of lateral bending moments. EMG activity was dependent on the direction and magnitude of the exertion, and also on the functional role. The mean NEMG of agonist was 0.260 and 0.067 for antagonist. Agonists showed the highest mean NEMG in flexion (0.367), while antagonists showed the highest mean NEMG in twisting clockwise/counter-clockwise (0.090/0.106).

• Journal of Korean Neurosurgical Society
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• 제62권5호
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• pp.519-525
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• 2019

Objective : The circadian pattern of the onset time of aneurysmal subarachnoid hemorrhage (aSAH) has been reported by various authors. However, the effect of the degree of physical exertion on the circadian pattern has not been studied in detail. Therefore, we conducted this study to investigate the effect of physical exertion on the circadian pattern of aSAH. Methods : Of the 335 patients presenting with aSAH from January 2012 to December 2017, 234 patients with identifiable onset time and metabolic equivalent (MET) values were enrolled. The onset time of aSAH was divided into 4-hour intervals. The patient's physical exertion was then assessed on a scale between 1 and 8 METs using generally accepted MET values, and categorized into two groups-light exertion (1 to 4 METs) and moderate to heavy exertion (5 to 8 METs)-to determine the effect of the degree of physical exertion on the onset time distribution of aSAH. Multivariate analysis was used to calculate the odds ratio (OR) between the two groups to determine the effect of the degree of physical exertion on each set of time periods. Results : There was a definite bimodal onset pattern that peaked at 08:00-12:00 hours followed by 16:00-20:00 hours (p<0.001). MET values at all time intervals were found to be significantly higher than the night time (00:00-04:00 hours) values (p<0.031). The MET value distribution showed a unimodal pattern that slightly differed from the bimodal distribution of the onset time of aSAH. There were no significant differences in the ORs of each time interval according to the degree of the MET value. Conclusion : This study reaffirmed that aSAH occurs in a bimodal pattern, especially showing the highest prevalence in the morning. Although aSAH could be related to daily activity, there were no significant changes in diurnal variations affected by the degree of physical exertion.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.450-457
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• 2022

The construction industry is demanding, dynamic, and complex making it difficult for workers to recognize hazards. The nature of construction tasks exposes workers to several critical risk factors, such as a high rate of exertion and fatigue. Recent studies suggest that fatigue may impact hazard recognition in the construction industry. However, most studies rely on subjective measures when assessing the relationship between physical fatigue and hazard recognition, limiting such studies' efficacy. Thus, this study examined the relationship between physical fatigue and hazard recognition using a controlled experiment. Worker fatigue levels were captured using physiological data and a subjective exertion scale. The findings confirmed that physical exertion plays a significant role in hazard recognition skills (p < 0.05). This research contributes to theory and practice by providing a process for objectively assessing the influence of physical fatigue on worker safety and providing construction professionals with some critical insight needed to improve workplace safety.

• 국제물리치료학회지
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• 제1권1호
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• pp.36-44
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• 2010

This study has been conducted on the subjects of eight undergraduate students with abdominal obesity and eight undergraduate students with normal weight to find out correlation between substantial fatigue and Ratings of perceived exertion through analysis of their blood components when they took exercises to strengthen their abdominal muscular power. Comparatively analyzing HDL-C, LDL-C and lactic acid before and after they took sit-up at level of RPE 19-20, no statistically significant differences in HDL, LDL, lactic acid measures were observed between groups, but a significant difference in RPE was noted between groups(p<0.05) Our findings suggest that control group showed no significant difference in increase of fatigue material whereas the obese group showed a lower frequency of sit-up, though both groups took the same abdominal exercise. Additionally, the lower frequency of sit-up in obese group results from relatively higher Ratings of perceived exertion rather than increase of substantial fatigue material. This study invites future research that examines the effect of a comprehensive obesity exercise program combined with dietetic on ratings of perceived exertion in individuals with obesity.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1995년도 춘계학술대회논문집
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• pp.72-83
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• 1995

This study are to investigate the variations of the recruitment patterns of the nine lower extremity muscles, and to analyze the changes of the role assigned to each muscle during the seated posture. For exertion levels, the transition point of type F more unit of each muscle is inferred by analyzing the electromyogram at the seated postures. Also, for predetermined seated foot operations exertion levels, the recruitment pattern and the changes of the role assigned are identified in the continuous exertion, by analyzing the electromyogram change sdue to the accumulated muscle fatigue. The developed model can be used to design and to assess the pedals and foot-related equipments design.

• 대한산업공학회지
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• 제19권3호
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• pp.103-111
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• 1993

There are four flexor muscles at elbow-biceps brachii, brachialis, brachioradialis, pronator teres. Muscle exertion force depends on the following conditions : elbow angle, external workload, and endurance time. The objectives of this study are to investigate the variations of the recruitment patterns of four muscles, and to analyze the changes of the role assigned to each muscle during elbow flexion. For three elbow angles, the transition point of type F motor unit of each muscle is inferred and the changes of the role assigned due to exertion level are identified by electromyographic analysis. The results showed that the recruitment pattern of biceps brachii is constant but those of other muscles are varied depending on elbow angle and exertion level. An EMG multiplexor is developed and simultaneous measurement of electromyographic signals of four elbow flexors is possible.

• 한국전문물리치료학회지
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• 제24권2호
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• pp.1-8
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• 2017

Background: Individuals with spinal cord injury (SCI) rely on their upper limbs for body-lifting activity (BLA). While studies have examined the electromyography (EMG) and kinematics of the shoulder joints during BLA, no studies have considered foot position during BLA. Objects: This study compared the effects of different foot positions during BLA on the shoulder muscle activities, peak plantar pressure, knee flexion angle, and rating perceived exertion in individuals with SCI. Methods: The study enrolled 13 mens with motor-complete paraplegic SCI, ASIA (American Spinal Injury Association) A or B. All subjects performed BLA with the feet positioned on the wheelchair footrest and on the floor independently. Surface EMG was used to collect data from the latissimus dorsi, pectoralis major, serratus anterior, and triceps brachii. The peak plantar pressure was measured using pedar-X and the knee flexion angle with Image J. Borg's rating perceived exertion scale was used to measure the physical activity intensity level. The paired t-test was used to compare the shoulder muscle activities, peak plantar pressure, knee flexion angle, and rating perceived exertion between the two feet positions during BLA. Results: The activity of the latissimus dorsi, pectoralis major, serratus anterior, and triceps brachii and rating perceived exertion decreased significantly and the peak plantar pressure and knee flexion angle increased significantly when performing BLA with the feet positioned on the wheelchair footrest compared with on the floor (p<.05). Conclusion: These findings suggest that individuals with SCI may perform BLA with the feet positioned on the wheelchair footrest for weight-relief lifting to decrease the shoulder muscle activities and the rating perceived exertion and to increase the peak plantar pressure and the knee flexion angle.

• 한국컴퓨터정보학회논문지
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• 제27권8호
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• pp.195-202
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• 2022

본 연구에서는 장시간 심폐소생술 지속 시 구조자의 혈중 젖산 농도, 심박동수, 운동자각도를 측정함으로써 구조자의 피로도 변화를 파악하고자 하였다. 자료수집은 2021년도 7월 5일부터 7월 9일까지 D 대학교 특전의무부사관과 학생 12명, 응급구조학과 학생 12명 총 24명을 대상으로 60분 동안 2인 교대 가슴 압박 소생술을 수행하였다. 연구 결과 심폐소생술 지속시간에 따른 구조자의 혈중 젖산 농도, 심박동수, 주관적 피로도인 운동 자각도, 가슴 압박 속도는 유의미한 변화가 있었다(p<.001, p<.001, p<.001, p<.001). 매 측정 주기(30분, 40분, 50분, 60분) 시 혈중 젖산 농도는 심박동수와 유의한 정적 상관관계가 나타났으며(r=.696, p<.001, r=.672, p<.001, r=.709, p<.001, r=.782, p<.001), 운동자각도와도 유의한 정적 상관관계가 나타났다(r=.476, p<.05, r=.426, p<.05, r=.470, p<.05, r=.470, p<.05). 따라서 장시간 심폐소생술이 요구되는 상황에서 심박동수와 운동자각도를 활용한 구조자의 피로도 모니터링은 고품질의 가슴 압박을 유지하는데 유용할 것이다.