• Journal of the Ergonomics Society of Korea
• /
• v.20 no.2
• /
• pp.71-82
• /
• 2001

Twisting posture in lifting tasks has been identified as a risk factor of low back pain. However, it has been usually estimated in terms of compressive stress or muscular activity. Thus, this study was conducted to predict the influence on muscular fatigue during lifting simulation. Fifteen young and healthy subjects were recruited and performed isometric trunk exertions during upright standing, two-level flexions and five-level asymmetric twisting conditions. EMG signals from five primary trunk muscles in right part of body were collected during 20sec for 45 different lifting conditions. RMS(root mean square) and MPF(mean power frequency) parameters were used to analyze the EMG signals. Twisting postures were significant in right erector spinae(ERSR), right latissimus dorsi(LATR), right internal oblique(INOR) for muscular activities. Especially, when trunk was $30^{\circ}$ CCW twisting posture. ERSR and INOR activities increased respectively by 11% and 3%. Regarding the trunk muscle fatigue, we found that MPF shifts in twisting posture increased 2.3 and 2.6 times for ERSR and INOR muscles respectively. Therefore, It is probable for workers to suffer from low back disorders when they were exposed to a extreme twisting posture during prolonged lifting. This study suggests NIOSH(National Institute for Occupational Safety and Health) lifting equation needs the time-duration multiplier in addition to asymmetric multiplier.

• Korean Journal of Exercise Nutrition
• /
• v.24 no.2
• /
• pp.38-46
• /
• 2020

[Purpose] This study aimed to investigate the effects of leucine-enriched essential amino acid (LEAA) supplementation on muscle fatigue and the level of inflammatory cytokines in wheelchair basketball players after a basketball game and interval training. [Methods] Of the ten recruited wheelchair basketball players (aged 34.5±8.9 years; lean body mass of 34.3±10.0 kg) who had spinal cord injury (SCI) and had undergone amputation, nine participated in the final test. These nine athletes received LEAA supplements (3 times 4.0 g/day) or placebo treatment in a double-blind, randomized, crossover study. We measured variables related to muscular fatigue and inflammatory response before the intense exercise and 4 days after recovery. [Results] The significant effect of LEAA supplementation was inhibition of circulating IL-6 levels in the LEAA-treated group compared with the placebo group (P < .05). However, no changes were observed in the TNF-α and creatinine kinase levels. Moreover, analysis of variance analysis showed no significant difference in the relative values of muscle soreness. However, the effect size analysis with Cohen's d reported a significant improvement in the relative values of whole body and back muscle soreness. [Conclusion] Our results revealed that LEAA supplementation before and after intense exercise could help reduce muscle soreness and IL-6 levels in wheelchair basketball players.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.50 no.5
• /
• pp.247-254
• /
• 2001

Silent period(SP) is transient stops of muscle activity that are induced by mechanical or electrical stimulus and the duration of silent period is a important parameter that have been associated with symptoms of masticatory dysfunction. Muscle fatigue is induced by sustained muscular contractions. It is associated with the external manifestations as the inability to maintain a desired force output, muscular tremor, and localized pain. Muscle fatigue is a parameter that have been measured or monitored the deterioration of a performance of muscles. On the study of relationship between SP and masticatory muscle fatigue, Nagasawa suggested that SP increases up to 3 min. from the beginning of clenching when the subjects performed sustained contractions at 50% maximum clenching level. In this paper, in order to evaluate a relationship between SP and muscle fatigue, 10 SPs per 1 minute are measured at 10%, 20%, 50% maximum clenching level. We used the median frequency in order to quantify the degree of muscle fatigue. However, the results shows that the duration of silent period was not significantly affected by differing levels of muscle fatigue. Therefore, we suggest that the SP is not increased or decreased as the results of muscle fatigue, also the origin of the SP generation mechanism is discussed.

• Journal of the Korea Safety Management & Science
• /
• v.11 no.4
• /
• pp.57-67
• /
• 2009

The psychosocial stress and musculoskeletal disorders(MSDs) have been one of major health problems for hospital workers. This study tried to understand the relationship between symptoms associated with MSDs and risk factors such as working posture, job stress, psychosocial stress and fatigue. A total number of 655 hospital workers participated in this study. Specifically, REBA was applied for evaluating working posture and a checklist prepared by KOSHA(Korean Occupational Safety and Health Agency) was used for symptom survey. A questionnaire from KOSHA was also used for collecting data associated with job stress, psychosocial stress and fatigue. All these data were formulated and modeled by path analysis which was one of major statistical tools in this study. Specifically, path analysis for the data we collected came up with several major findings. As a result, as for body part(neck), (waist) and (arms) the degree of risk of work posture measured with the use of job stress(KOSS), psycho-social stress(PWI-SF) and REBA is significantly more affected by fatigue than muscular skeletal disease related consciousness symptom. However, regarding bod(wrist), the degree of risk of work posture measured with the use of job stress(KOSS) and REBA is directly affected by muscular skeletal disease related consciousness symptom. This study is meaningful in that the study clarified the causal relations of the degree of risk of work posture, degree of fatigue, and muscular skeletal disease related consciousness symptoms by each body part measured with the use of work stress(KOSS), psycho-social stress(PWI-SF) and REBA.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.36 no.6
• /
• pp.678-682
• /
• 2007

Effects of medicinal herbs on the improvement of muscular strength along with the related fatigue factors were evaluated in SD rats. Nine types of treatment groups were fed diets supplemented with 1% herb hot-water extracts (Liriope spicata (LS), Schizandra chinensis (SC), Acanthopanax sessiliflorus (AS), Saliconia herbacea (SH), Eucommia ulmoides (EU), Lycium chinensis (LC), Panax ginseng (red ginseng) (PG), Polygonum multifloum (PM), Glycyrrhizae uralensis (GU)) for 4 weeks. The muscular strength of all groups were measured weekly for 4 weeks. After 4 weeks serum was collected and liver dissected out for the analysis of glycogen and fatigue factors. The liver glycogen contents of all treatment groups ($21.0{\sim}25.9mg/g$) were higher than that of control group (18.1 mg/g). A significantly increase of muscular strength in the fourth week were found in the AS (282.5 gf), SH (277.4 gf), PG (287.2 gf) groups (p<0.05). LS (7.88 mg/dL), SC (7.85 mg/dL), AS (7.64 mg/dL), EU (7.54 mg/dL), LC (7.81 mg/dL) and PG (7.75 mg/dL) groups were significantly reduced in serum inorganic phosphorus concentration measured after 4 weeks (p<0.05). Serum lactate levels of treatment groups ($8.61{\sim}12.18{\mu}g/dL$) were significantly lower than that of control group ($17.45{\mu}g/dL$). These results suggest that medicinal herbs enhanced muscular strength of rats by delaying accumulation of muscular fatigue factor.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.4 no.2
• /
• pp.143-152
• /
• 2000

As muscular contraction is sustained, the Fourier spectrum of the myoelectric signal is shifted toward the lower frequency. This spectral density is associated with muscle fatigue. This paper describes a quantitative measurement method that performs the measurement of localized muscle fatigue by tracking changes of median frequency based on stationary wavelet transform. Applying to the human masseter muscle, the proposed method offers the much information for muscle fatigue, comparing with the conventional FFT-based method for muscle fatigue measurement.

• The Journal of Korean Obstetrics and Gynecology
• /
• v.20 no.2
• /
• pp.60-70
• /
• 2007

Purpose: This study was conducted to investigate the muscle anti-fatigue effects of Allii tuberosi semen after short term administration. Methods: 4-6 weeks old ICR mice were used in this study and we administered the water soluble extracts of Allii tuberosi semen in the concentration of 1, 10 and 100mg/0.3ml to each 5 mice (ATS group) and same volume of normal saline was administered to 5 mice (control group) once a day for 30 or 60 days. After the administration we performed the swimming exercise test and the grip strength test. And we measured the concentration of glucose and the activity of lactate dehydrogenase in plasma regarded as biochemical indicator related with the muscular fatigue.. Results: In swimming exercise test. 10 and 100mg/0.3ml ATS groups showed increased time compared with relative control group after 30 days administration. But after 60 days adminstration all ATS groups showed increased results. In grip strength test, 100mg/0.3ml ATS group increased grip strength after 30days administration and 10mg/0.3ml ATS group showed increased result after 60days administration. All the results of plasma glucose and lactate dehydrogenase didn't showed statistically significant difference after 30 and 60 days administration. Conclusion: From this study we could find the anti-fatigue effect of Allii tuberosi semen in the muscle strength related test.

• Journal of the Korean Society for Precision Engineering
• /
• v.28 no.12
• /
• pp.1434-1440
• /
• 2011

In this paper, we assessed muscular activities of lower limbs and foot pressure for car and bus drivers according to operating three electronic pedals that we developed. To analyze drivers' physical exhaustion, muscular fatigue of lower limbs was evaluated. Eleven car drivers and six urban bus drivers were participated in this experiment. The virtual driving system was used for the real driving environment. The virtual driving system was comprised of a spring seat, a steering wheel, pedals (clutch, excel and brake pedals), a manual transmission and a virtual driving simulation. For the real vibration like situation on the road, six degree of freedom motion base system was used. Measured muscles were rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA) and gastrocnemius (Gn) muscles. For the quantitative muscular activities, integrated electromyography (IEMG) was analyzed. Muscular fatigues also were analyzed through the analysis of the median frequency. In addition, foot pressures were analyzed and compared through the peak and averaged pressure during the operating three developed electronic pedals. The experiments are conducted with total 17 drivers, 11 general public and 6 drivers. As a result of the analysis, electromyogram and fatigue analysis through intermediate frequency reduction for pedal-1 more efficient than other pedals. And foot pressure also was decreased. Consequently, we suggested the most efficient pedal and method to minimize the amount of cumulative fatigue.

• Journal of Convergence for Information Technology
• /
• v.8 no.6
• /
• pp.93-99
• /
• 2018

The purpose of this study was to prove the effect of passive stretching after delayed muscular pain induction in university students and to propose a rehabilitation exercise program for effective pain relief and prevention in case of injury. Subjects were divided into passive stretching group and control group. Passive stretching group was performed passive stretching after delayed muscular pain induction and control group did not perform any treatment after delayed muscular pain induction. The delayed muscular pain induction method was induced by bench step motion. The height of the step box was 50cm. The data were analyzed by two-way RGRM ANOVA for comparison of passive stretching group and control group. In conclusion, passive stretching after delayed myalgia has a positive effect on blood fatigue (CRP, LDH) and subjective pain scale(VAS).

• International Journal of Industrial Entomology and Biomaterials
• /
• v.5 no.1
• /
• pp.109-122
• /
• 2002

The purpose of this investigation is to evaluate the effects of the Nuegra on enhancement of the masculine and physical activities in general through measuring changes of the testosterone, FSH and subjective symptoms like fatigue, insomnia, urinary stream, muscular weakness, libido and erectile dysfunction. Total 168 male subjects were enrolled from 12 urology, internal medicine clinics and general practitioner, During the 6-week investigational period, 2 capsules of Nuegra were given to the subjects right after meal for 4 weeks, and 1 capsule of Nuegra was added each time in subjects with no or minimal effect. Testoster-one and FSH levels were measured at first visit and last visit, for evaluating masculine activities. To avoid bias and standardize the test results, only one clinic was assigned as a central lab, and all blood samples were transferred. General information and subjective symptoms were evaluated at first visit and at 2 weeks interval, week 2, 4 and 6 using VAS (Visual Analogue Scale). The mean age of the subjects were 51.8${\pm}$8.2 years old (range: 36.1-82.1). Based on the subjects who were tested on testosterone and FSH levels at day l and week 6, the means were 4.4${\pm}$1.4 nmol/L (range: 2.6-7.7), 8.6${\pm}$9.6 mIU/mL (range: 0.3-40.4), respectively at day 1. At week 6, the results were 4.9 ${\pm}$1.6 (2.6-8.9 range), 9.4${\pm}$13.1 (1.0-53.9 range), respectively. Marginally significant difference between pre-dose and post-dose was present. Statistically significant differences were revealed in general assessment for subjective symptoms, fatigue, insomnia, erectile dysfunction, etc. In fatigue, response rates were 39.6, 65.4 and 76.4% at week 2, 4 and 6, respectively (P < 0.0001). Response vates for erectile dysfunction were 13.4, 41.2 and 72.7% at week 2, 4, and 6 (P < 0.0001), respectively, Response rates for libido were 13.6, 51.6 and 73.5% at week 2, 4, and 6 (P < 0.0001), respectively. For urinary stream response rates were 26.9, 44.7 and 66.8% at week 2, 4, and 6 (P < 0.0001), respectively. VAS for muscular weakness did not show significant results that response rates were 40, 60 and 80% at week 2, 4, and 6 from 8.2 (P ＝ 0.24), respectively. Response rates for insomnia were 50, 60, 100% at week 2, 4, and 6 (P < 0.0001), respectively. The results shows that Nuegra tends to enhance masculine activities including libido, erectile dysfunction and urinary stream and also effective for improving general conditions especially insomnia, muscular weakness and fatigue. In conclusion, this investigation has demonstrated that Nuegra does not only have tendency to increase masculine activities through increased secretion of the testosterone and FSH but also improve general conditions such as erectile dysfunction, libido, fatigue and muscular power.