• Nutrition Research and Practice
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• 제16권1호
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• pp.106-119
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• 2022

BACKGROUND/OBJECTIVES: This study aimed to examine the reproducibility of food frequency questionnaires (FFQs) designed for young female nurses in the Korea Nurses' Health Study. SUBJECTS/METHODS: The reproducibility of web-based, self-administered FFQs was evaluated among 243 Korean female nurses. The first FFQ (FFQ1) was administered from March 2014 to February 2019 and the second FFQ (FFQ2) from November 2019, with a mean interval of 2.8 years between the FFQs (range, 9 months-5.6 years). Pearson and Spearman correlation coefficients (r values) and quartile agreements between FFQ1 and FFQ2 were calculated for intakes of energy, nutrients, and foods. RESULTS: Pearson correlation coefficients ranged from 0.41 to 0.55 (median r = 0.51) for energy and raw nutrients and from 0.16 to 0.46 (median r = 0.36) for energy-adjusted nutrients. Spearman correlation coefficients ranged from 0.25 to 0.72 (median r = 0.41) for food items. The percentages of women who were classified into the same or adjacent quartile were 77% to 84% (median = 82%) for raw nutrients and 69% to 86% (median = 78%) for foods. CONCLUSIONS: The results indicated that the web-based FFQ used in the Korea Nurses' Health Study has acceptable reproducibility.

• 한국전문물리치료학회지
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• 제6권2호
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• pp.16-31
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• 1999

The purpose of this study was to assess the fatigue in lumbar and abdominal muscles in patients with chronic low back pain compared with normal subjects using spectral analysis with mean power frequency and median power frequency. The experimental group consisted of twenty subjects who had experienced chronic low back pain for over one year after the onset day. A control group consisted of twenty normal subjects with no history of low back pain. All subjects stood in an apparatus to perform sustained contraction in the lumbar and abdominal muscles for 30 seconds with 60% maximal voluntary isometric contraction (MVIC). The resulting electromyographic (EMG) recorded time serial data were transformed into frequency serial data by Fast Fourier Transformation (FFT). The results were as follows: 1) lumbar muscles measured, the frequency change ratio of both median power frequency and mean power frequency was significantly greater for experimental group compared with control group group (p<0.05). In measured two abdominal muscles (inferior rectus abdominis, obliquus externus abdominis) except superior rectus abdominis, the frequency change ratio of both median power frequency and mean power frequency was significantly greater for experimental group compared with control group (p<0.05). 2) In all three (longissimus thoracis, iliocostalis lumborum, multifidus) lumbar muscles measured, the initial frequency value of both median power frequency and mean power frequency was significantly lower for the experimental group compared with the control group (p<0.05). In the two (inferior rectus abdominis, obliquus externus abdominis) abdominal muscles measured (superior rectus abdominis not included), the initial frequency value of both median power frequency and mean power frequency was significantly lower for the experimental group compared with the control group (p<0.05). These results suggest that in patients with chronic low back pain there is a trend for more fatigue to occur in both lumbar and abdominal muscles than in the normal control group. This would seem to suggest that in treatment programs for patients with chronic low back pain, improvement of endurance in all trunk muscles should be considered.

• The Journal of Korean Physical Therapy
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• 제18권1호
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• pp.83-94
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• 2006

Purpose: This study conducts quantitative evaluation or structural and functional characteristics or normal skeletal muscle with ultrasound image and surface electromyography, and is to provide basic materials for utilizing ultrasound image analysis in physical therapy diagnosis and assessment of skeletal muscle. Methods: Measurement of three stages was conducted with 88 normal adults between their twenties and seventies, correlations and differences using collected data according to age and gender were compared and correlations among measured items were analyzed and then the following conclusions were obtained. Results: Analysis of ultrasound image of normal skeletal muscle showed that density, median frequency had the closest relations with age. In addition, it was found that there were high correlations between density explaining structural characteristics of skeletal muscle and median frequency explaining functional characteristics. Conclusion: Analysis of ultrasound image makes complex evaluation of structure and function of skeletal muscle possible when it is connected with functional evaluation method using physical measurement surface electromyography as well as quantitative evaluation of structural changes of skeletal muscle and is effective in complementing physical therapy diagnosis centering around functionality evaluation.

• 한국전문물리치료학회지
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• 제16권3호
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• pp.16-23
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• 2009

The purpose of this study was to investigate the effects of a repetitive lifting task on the level of activation and median frequency of the paraspinal muscles, and to provide basic data of the maximal acceptable duration of the lifting task to avoid muscle fatigue. Ten healthy male subjects were recruited as participants and they repetitively (12 lifts/min) lifted a box ($46cm{\times}30cm{\times}30cm$, 15 kg) for 10 minutes. Electromyographic data (muscle activation and median frequency), heart rate, and Borg CR10 score were recorded at 1, 3, 5, 7, and 9 minutes after the lifting task. Electromyographic data was recorded from the elector spinalis, mutifidus, external oblique abdominis, and rectus abdominis for 1 minute. The results showed that as the repetitive lifting task progressed, the heart rate and Borg CR10 score significantly increased. In addition, activation of the muscles increased. The median frequency significantly decreased over time in the elector spinalis, mutifidus, and external oblique abdominis (right side), except for the external oblique abdominis (left side) and rectus abdominis. It is suggested that the median frequency recorded from a dynamic task is used to monitor muscle fatigue. Furthermore, the repetitive lifting task (15 kg, 12 lifts/min) should not continue for more than 3 minutes in order to avoid muscle fatigue.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권5호
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• pp.380-388
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• 2004

This study proposed an improved spike detection algorithm which automatically detects suitable spike threshold on the amplitude of surface electromyography(SEMG) signal during isometric contraction. The EMG data from the low back muscles was obtained in six channels and the proposed signal processing algorithm is compared with the median frequency and Gabriel's spike parameter. As a result, the reliability of spike parameter was inferior to the median frequency. This fact indicates that a spike parameter is inadequate for analysis of multi-channel EMG signal. Because of uncertainty of fixed spike threshold, the improved spike detection algorithm was proposed. It automatically detects suitable spike threshold depending on the amplitude of the EMG signal, and the proposed algorithm was able to detect optimal threshold based on mCFAR(modified Constant False Alarm Rate) in the every EMG channel. In conclusion, from the reliability points of view, neither median frequency nor existing spike detection algorithm was superior to the proposed method.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제4권2호
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• pp.143-152
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• 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.

• 한국운동역학회지
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• 제17권2호
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• pp.239-245
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• 2007

The purpose of this study was to compare the electromyography signal's power spectrum mean and median tendencies appearing in the lower extremity during walking while wearing roller shoes. 9 male subjects volunteered who have no experience riding inline-skate or roller-skate, and have no record of musculoskeletal disorder. Subjects walked on treadmill twice for an hour (Once a week, one trial with the roller on and the other without roller, Walking velocity = 1.39 m/s). Electromyography was measured every 15 minute (0, 15, 30, 45, 60 minutes). Surface electrode sticked muscle at rectus femoris(R.F.), vastus lateralis(V.L.), vastus medialis(V.M.), biceps femoris(B.F.), tibialis anterior(T.A.), gastrocnemius lateralis(G.L.), gastrocnemius medialis(G.M.). At Rectus femoris, Vastus Lateralis, Vastus medialis, and Biceps femoris showed no statistically significant decrease of median frequency or mean edge frequency as time passes. Also, between two treatments (wearing the roller shoes vs not wearing the roller shoes), no statistically significant difference. After 60 minutes, mean edge frequency showed statistically significant decrease at tibalis anterior and after 45 minutes, mean edge frequency showed statistically significant decrease compared to wearing roller shoes without the wheels at gastrocnemius lateralis. At gastrocnemius medialis after 30 minutes, median frequency showed statistically significant decrease, and showed statistically significant difference compared to the control group. Wearing the roller shoes with wheels for a long time resulted in statistically significant decrease of mean edge frequency and median frequency in lower extremity, especially in shank muscles. Increase of wearing time of roller shoes and walking on a bumpy road wearing roller shoes with wheels result fatigue and thus, danger of injury.

• 대한의용생체공학회:의공학회지
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• 제21권2호
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• pp.219-224
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• 2000

본 연구는 몸통의 반복적인 flexion/extension 동작 수행시 근전도신호를 측정하고 이들 신호에서 나타난 EMG parameters(median frequency, median power, RMS) 와 피실험자의 주관적 불편도의 변화양상간의 정량적인 관계를 알아보고자 수행되었다. 피실험자별로 3-5회 정해진 업무를 수행하였고 주관적불편도와 근전도 신호를 측정하였다. 실험결과 반복횟수가 증가할수록 주관적 불편도는 증가하였으며 각 task 별로 EMG parameter와 불편도의 증감율 간의 회귀분석과 상관분석을 수행한 결과 실험과 EMG parameter에 따른 변이는 존재했지만 대체로 RMS에 비해 MF와 MP의 증감율이 불편도 증감율과 상관관계가 높은 것으로 나타났다.

• 한국정보전자통신기술학회논문지
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• 제2권1호
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• pp.17-22
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• 2009

본 연구에서는 근전도의 근피로와 관계된 특징인자인 영교차율 및 저대역에너지, 푸리에변환과 AR모델에 의한 중앙주파수를 추출하여 근피로에 이를 때까지의 변화를 평가해 봄으로써 근피로 정도나 시점까지의 변화 정도를 비교 및 고찰하고자 한다. 측정 대상으로 20대 남녀 각각 3인이 참여하였으며 상완 이두근의 등장성운동으로 소진할 때까지의 근전도를 측정 기록하여 실험하였다.

• 구강회복응용과학지
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• 제29권4호
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• pp.337-346
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• 2013

정중설공은 하악 전치부에 존재하는 해부학적 구조물로서, 구강저의 혈행을 담당하는 설하 동맥이 통과한다. 임플란트 시술 시 설하 동맥의 손상으로 인한 대량 출혈을 예방하기 위해서는 CBCT를 통한 정중설공의 주의 깊은 관찰이 필요하다. 본 연구의 목적은 하악 정중설공의 해부학적 특성인 출현빈도, 위치, 직경과 그 수를 성별과 나이에 따라 CBCT 이미지를 이용하여 평가하기 위함이다. 2008년 11월부터 2011년 5월까지 전남대학교 치과병원을 내원한 62명의 CBCT 이미지(남성 41명, 여성 21명; 평균 연령 43세; 연령 분포 9~85세)를 평가하였다. 하악 전치부 CBCT에서 관찰되는 정중설공의 출현빈도, 수, 위치, 수직적 거리와 직경을 계측하였다. 62명의 환자(100%) 모두에서 설극 상방에 1개 이상의 정중설공을 관찰할 수 있었고, 56명(90.32%)은 다수의 정중설공을 가지고 있었다(2개 64.52%, 3개 25.8%). 42명(66.13%)의 환자에서 하악 양 중절치 사이의 정중설공을 관찰할 수 있었다. 치조정에서 설극까지의 평균 높이는 24.21 mm 였고, 하악골 하연에서 정중설공까지의 평균높이는 14.53 mm, 하악골에서의 상대적인 높이는 0.45였다. 설공의 평균 직경은 0.93 mm였다. CBCT를 통해 정중설공의 출현빈도, 위치, 직경과 그 수를 쉽게 확인할 수 있다. 전치부 임플란트 시술 시 대량 출혈의 합병증을 예방하기 위해서는 임플란트 식립 전 CBCT를 촬영하여 개개인의 정중설공의 해부학적 평가하는 것이 필요할 것이다.