Issues : JET is a peer-reviewed, open-access scientific journal : Journal of Ergonomic Technology (JET)

Journal of Ergonomic Technology (JET)
ISSN 2432-1575


Influence of the menstrual cycle on sleep parameters and autonomic nervous response
Publish Date : 2018/07/12  Vol.18
Authors : 
Michiko Tanaka, Miyazaki Prefectural Nursing University
Mou Nagasaka, Miyazaki Prefectural Nursing University
Chiyomi Egami, Fukuoka Prefectural University
Miyuki Kondo, Fukuoka Prefectural University
Kiyoka Yamashita, Fukuoka Prefectural University
Yoshikazu Sakakibara, Kanazawa Institute of Technology (Prof. Emeritus)
Report Outline : 
Background: The aim of this study was to investigate differences in sleep patterns, sleep quality, and autonomic nervous responses during the follicular phase (FP) and luteal phase (LP) of the menstrual cycle.
Participants and Methods: Fifteen healthy women aged 19–30 years participated in the present study, and the following measurements were carried out in their homes for 2 nights during each of the two menstrual phases. The data obtained in the first night were excluded to get rid of first-night effect. We examined the R-R interval variability for 150 min from the onset of sleep, and objective measurements of some sleep parameters were recorded using Nemuri Scan mat placed beneath the participant’s mattress. The following morning, participants recorded their subjective perceptions of the parameters. Changes in autonomic functions were estimated by the time domain for RR intervals or the Lorenz plot method. The parameters were compared between FP and LP using Wilcoxon signed rank test and the correlation was tested using Spearman correlations.
Results: We found no significant differences between the sleep parameters in FP and those in LP. We found a positive correlation between sleep quality and total sleep time (r = 0.552, P = 0.041) or the basal body temperature (r = 0.684, P = 0.007) in LP, but not in FP (r = 0.138, P > 0.05; r = −0.354, P > 0.05). We observed correlations between total sleep time and the square root of the mean squared differences of successive RRIs for 150 min after sleep onset in autonomic nervous response parameters in FP (r = −0.538, P = 0.047) and in LP (r = −0.525, P = 0.054). However, we observed correlation between total sleep time and the longitudinal variability / transverse variability of Lorenz plot for 150 min after sleep onset in FP (r = 0.591, P = 0.026), but not in LP (r = 0.424, P = 0.131).
Conclusions: It is suggested that sleep quality may be correlated with total sleep time in LP, and total sleep time may have a stronger correlation with the autonomic nervous response in FP than that in LP. We observed that sleep during the menstrual cycle is influenced by the autonomic nervous response of sleep onset. The balance of sympathetic and parasympathetic nervous responses may affect total sleep time.

Key words: sleep parameters, sleep quality, menstrual cycle, autonomic nervous response
Count : 646
A Study of the Color Features Related to the Feeling of “Han-nari” in Women’s Japanese Kimono
Publish Date : 2018/07/01  Vol.18
Authors : 
Kumiko Komizo, Graduate School of Science and Technology, Kyoto Institute of Technology
Satoshi Kitada, Faculty of Science and Technology, Kyoto Institute of Technology
Noriaki Kuwahara, Graduate School of Science and Technology, Kyoto Institute of Technology
Report Outline : 
Purpose: By using ten different types of kimono images, we investigated the physical quantities that constitute the feeling of “Han-nari”, a term used for expressing a certain kind of beauty specific to kimonos.

Participants and methods: Thirty students (22 males and 8 females) participated the experiment. Ten kimono images were shown on a screen, and the participants evaluated them based on their degree of “Han-nari”. The images were analyzed with RGB histograms and with u’,v’ chromaticity diagrams that were converted from RGB values. The brightness of the images was measured with brightness-meter.

Result: We found that the kimonos with “white” and “whitish yellow” colors strongly influenced the degree of “Han-nari” reported, and as the brightness of the kimono image increased, it showed a clear correlation with an increase in the reported degree of “Han-nari”.

Conclusions: Quantifying the feeling of “Han-nari” makes it possible to extract one factor of the beauty of kimono. Until now, the sense of “Han-nari” that a kimono might have depended entirely on the tacit knowledge of craftsmen. However, in order to clarify the definition of “Han-nari” by utilizing numerical values, kimonos that evoke a sense of “Han-nari” could be created by industrial production. This could eventually help to revive the kimono industry and is useful in passing kimono culture on to future generations. We were able to quantify the color and brightness associated with a sense of “Han-nari” in this research. This method is not limited to kimonos and could be applied to other industrial products.

Keywords: kansei, color, brightness, kimono; obi
Count : 593
Difference in response times on hand mental rotation task between the back
and palm of the hand in elderly individuals
Publish Date : 2017/12/28  Vol.17
Authors : 
Izumi Nagashima, Doctoral course, Graduate School of Health Sciences, Kyorin University, Department of Occupational Therapy, Faculty of Health Sciences, Kyorin University
Kotaro Takeda, Faculty of Rehabilitation, School of Health Sciences, Fujita Health University
Yutaka Sato, Graduate School of Technology, Industrial and Social Sciences, Tokushima University
Hideki Mochizuki, Department of Occupational Therapy, Faculty of Health Sciences, Kyorin University
Yusuke Harada, Department of Occupational Therapy, Faculty of Health Sciences, Kyorin University
Nobuaki Shimoda*, Department of Occupational Therapy, Faculty of Health Sciences, Kyorin University
Report Outline : 
Purpose: The hand mental rotation task (HMRT), in which participants judge whether a picture of a hand is of the left or right hand, is thought to induce a participant’s motor imagery. This application of this task in rehabilitation has begun. However, the task performance strategy used on presentation with a picture of the back of the hand and the palm in elderly individuals has not been sufficiently elucidated. In this study, we examined the performance strategy of the HMRT in response to pictures of the back of the hand and the palm among elderly individuals.
Participants and methods: A total of 75 right-handed individuals aged 65 years or older (38 men and 37 women, 74.9 ± 5.8 years old) were included in this study. From the position in which the middle finger was located at 0 degrees vertically, the pictures of the left/right hand and the back of the hand/the palm were turned in increments of 60 degrees in presentation, and the response time (RT) and correctness of responses were recorded. The RT to the left and right arrows was also measured, and the ΔRT was derived by subtracting the RT to the arrows from the RT to the hand pictures. A repeated measures ANOVA was conducted on the ΔRT with three factors: whether the hand was left or right, whether the back of the hand or the palm of the hand was pictured, and the presented angle.
Conclusions: We suggest that the motor imagery strategy was combined with the visual imagery strategy when pictures of the back of the hand were presented and that the motor imagery strategy was used when pictures of the palm were presented. These results indicate that frequent use of pictures of the palm may be effective when the HMRT is used for rehabilitation of elderly individuals.
Keywords: Motor imagery, Visual imagery, Aging, Rehabilitation, Motor response generation
Count : 1939
Pain related to breastfeeding in seated and side-lying positions: assessment and recommendations for improved guidance
Publish Date : 2017/10/24  Vol.17
Authors : 
Makiko AOKI, Kanagawa Institute of Technology
Satoshi SUZUKI, Kanagawa Institute of Technology
Hidenobu TAKAO, Kanagawa Institute of Technology
Fumitaka IKARASHI, Graduate School of Engineering, Kanagawa Institute of Technology
Report Outline : 
Purpose: To explore the relationship between breastfeeding positions and pain in the upper arms and shoulders.
Subjects and Methods: Twelve subjects with breastfeeding experience participated in an experiment and survey. In the experiment, subjects embraced two dummy infants with different weights, in six different positions, such as the cradle hold and side-lying hold, while electromyography (EMG) and video were recorded at six sites: the right and left forearms, upper arms, and shoulders. The survey asked for responses to 37 items such as sites where pain was felt during breastfeeding, type of hold during breastfeeding, and guidance received from medical institutions or other advisors.
Results: The 11 subjects who provided valid data were analysed. In training and practice with breastfeeding positions at medical institutions, only two subjects had received guidance on the side-lying hold, but 10 had used it. In terms of the positions of the upper arms in each hold, seven patterns were observed for the side-lying hold. Spearman’s rank correlation coefficient for left/right location of chronic pain and frequency of breastfeeding with the left/right breast was 0.95 (p<0.01). Eight of 10 subjects who had performed the side-lying hold felt short-term pain in the upper arm and shoulder of the breastfeeding side (the bottom side in the lateral decubitus position).
Conclusion: Of six breastfeeding positions, the one most frequently linked to pain was the side-lying hold. It also became clear that uneven breastfeeding with the right and left breasts in the side-lying hold, or the use of a self-taught side-lying hold position, produced short-term pain that was linked to lactation-stage pain. This shows that guidance on the proper use of the side-lying hold is needed. There is also a need for further investigation that distinguishes between different side-lying hold positions, to support teaching of appropriate body positions. Research on breastfeeding positions has the potential to reduce the burden of child-rearing on mothers and contribute to a healthier child-rearing environment.

Keywords: Breastfeeding positioning, EMG, Pains of upper arms and shoulder, Side-lying, After birth and parenting support
Count : 2367
Validity and reliability of Leap Motion Controller for assessing grasping and releasing finger movements
Publish Date : 2017/10/04  Vol.17
Authors : 
Shuntaro OKAZAKI, Faculty of Human Sciences, Waseda University, Saitama, Japan
Yoshihiro MURAOKA, Faculty of Human Sciences, Waseda University, Saitama, Japan
Risa SUZUKI, Faculty of Human Sciences, Waseda University, Saitama, Japan
Report Outline : 
Objective: The leap motion controller (LMC) is a motion sensor that has recently become available and has advantages in terms of cost, size, and accuracy. However, it has not been fully investigated whether the LMC has sufficient accuracy for clinical assessments, particularly finger flexion and extension, which are important for diagnosis and prognosis in stroke or cerebral palsy patients. Herein, we have tested the validity and reliability of the LMC for measuring the grasp and release of finger movements.
Materials and methods: A healthy participant repeated finger flexion and extension movements, and his fingertip position was measured using an LMC from the palmar, ulnar, and dorsal sides of the hand. The fingertip position was also measured using an electromagnetic motion tracker and a video. The finger movement detected by the LMC was compared with those detected by the other instruments.
Conclusions: The LMC had a higher reliability in detecting the fingertip position by sensing it from the palmar or dorsal side of the hand, compared with the ulnar side. In the palmar/dorsal side measurements, an underestimation in the amplitude of the finger movement was shown in the middle range of its excursion compared to video-detected movement. However, the underestimation resulted in a highly correlated, proportional bias, especially in the palmar-side measurement, and could be calibrated by a nonlinear regression analysis. The palmar side measurement was thus the most suitable for evaluating the finger flexion and extension. We concluded that by taking into consideration the range of excursion and appropriate calibration, the validity and reliability of the LMC is sufficient for the quantitative evaluation of finger flexion and extension in laboratory experiments and also in clinical settings.

Keywords: Motion capture; Spasticity; Grasping; Bland–Altman plot
Count : 2349
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