It is commonly known that autonomic modulations are caused by depression, fatal arrhythmia, and vascular disease. This may lead to be an urgent need of a reliable physiological technology to evaluate autonomic modulations. The specific purpose of the current study is to examine the possibility of whether the Acceleration Plethysmography (APG) system can become a new useful tool to measure autonomic modulations. We verified the heart rate variability (HRV) analysis by APG whether it can be used as same as by the ECG. The HRV is interpreted from the a-a interval (Taa) on APG waves. We assembled the simultaneous measurement system of APG and ECG, examined the identities of the R-R interval (TRR) of ECG and the Taa of APG in six subjects of 22-60 old, and then compared variables in frequency domains of HRV by both APG and ECG. The results showed a close correspondence of the Taa and the TRR . Furthermore, when the regression formula was set as Taa=C*TRR, the coefficient of regression (C) was 1.0002, 1.0001, 0.9997, 1.0000, 0.9999, 1.0001 respectively; whereas for each subject, the coefficient of determination was 0.9901, 0.9892, 0.9968, 0.9740, 0.9676, 0.9677 respectively (p<0.01). As for the difference between APG and ECG, the coefficient of variation of HRV was merely 0.1-0.2%, and the LFIHF ratio as 0.1-0.4. If we carefully interpret the results of the frequency analysis, the APG system can be a useful objective methodology to evaluate autonomic modulations. Because of its simplicity in usage, it is expected to be employed in the occupational health or primary care.
ObjectiveTo examine the effects of the length and timing of nighttime naps on performance and physiological functions, an experimental study was carried out under simulated night shift schedules. Methods Six students were recruited for this study that was composed of 5 experiments. Each experiment involved 3 consecutive days with one night shift (22:00-8:00) followed by daytime sleep and night sleep. The experiments had 5 conditions in which the length and timing of naps were manipulated: 0:00-1:00 (E60), 0:00-2:00 (E120), 4:00-5:00 (L60), 4:00-6:00 (L120), and no nap (No-nap). During the night shifts, participants underwent performance tests. A questionnaire on subjective fatigue and a critical flicker fusion frequency test were administered after the performance tests. Heart rate variability and rectal temperature were recorded continuously during the experiments. Polysomnography was also recorded during the nap. Results Sleep latency was shorter and sleep efficiency was higher in the nap in L60 and L120 than that in E60 and E120. Slow wave sleep in the naps in E120 and L120 was longer than that in E60 and L60. The mean reaction time in L60 became longer after the nap, and faster in E60 and E120. Earlier naps serve to counteract the decrement in performance and physiological functions during night shifts. Performance was somewhat improved by taking a 2-hour nap later in the shift, but deteriorated after a one-hour nap. Conclusions Naps in the latter half of the night shift were superior to earlier naps in terms of sleep quality. However performance declined after a 1-hour nap taken later in the night shift due to sleep inertia. This study suggests that appropriate timing of a short nap must be carefully considered, such as a 60-min nap during the night shift. Resumo ObjetivoPara investigar os efeitos da duração e horário de cochilos noturnos sobre o desempenho e as funções fisiológicas foi realizado um estudo experimental por meio do trabalho noturno simulado.
The aim of the present study was to reveal characteristic patterns of fatigue feelings on consecutive night shifts by a questionnaire for work-related fatigue feelings "Jikaku-sho shirabe". Ten healthy males (Mean +/- SD: 22.9 +/- 3.2 years old) participated in the experiment. Participants were required to attend the laboratory for nine consecutive nights under the following conditions: adaptation sleep (0:00-7:00), simulated day shift (10:00-18:00), baseline sleep (0:00-7:00), directly followed by four simulated night shifts (22:00-9:00) and the subsequent daytime sleep (12:00-18:00), three recovery nights (0:00-7:00) and two simulated day shifts (10:00-18:00). During each simulated shift, participants were required to complete an English transcription task (30 min), a performance test battery (20 min) and break (10 min) every hour. Fatigue feelings were evaluated by "Jikaku-sho shirabe", which was proposed by the Industrial Fatigue Research Committee of the Japan Occupational Health in 2002. This questionnaire consists of 25 subjective fatigue symptom items that are categorized into 5 factors: feeling of drowsiness (Factor I), feeling of instability (Factor II), feeling of uneasiness (Factor III), feeling of local pain or dullness (Factor IV), and feeling of eyestrain (Factor V). For each item, respondents are requested to estimate the intensity of the feelings as "Disagree at all," "Agree scarcely," "Agree slightly," "Agree considerably," and "Agree strongly." These five intensities were assigned scores of 1 to 5 points, respectively. Hierarchical cluster analysis suggested that there might be at least three variation patterns of fatigue feelings on the consecutive night shifts (i.e. Clusters A, B and C). On the basis of subjective fatigue symptom items of each cluster, the patterns in Clusters A, B and C might reflect the loads of the reticular activating system, musculoskeletal and central nervous systems, and limbic system, respectively. For Clusters A and C, significant improvements were observed with the increase of the number of night shifts (F(11,99)=3.07, p<0.01, F(11,99)=3.37, p<0.01, respectively). On the other hand, Cluster B deteriorated with the progress of the simulated night shifts. Taken together, we suggest that the characteristic patterns of fatigue feelings on consecutive night shifts might represent dissociation among the feelings induced by several loads.
山田翔太 2,3 ,榎原 毅 2 ,上原 徹 3 ,稲田 充 3 ,上島通浩 2 Pelvic incidence (PI) , which is measured by lateral spine radiography, has been attracting attention Pelvic incidence (PI) , which is measured by lateral spine radiography, has been attracting attention as one of the determinants of low back pain. This study assessed the external validity of the Kendall as one of the determinants of low back pain. This study assessed the external validity of the Kendall postural types and the Camper plane categories using their estimated PIs with a validated non-invasive postural types and the Camper plane categories using their estimated PIs with a validated non-invasive way. In addition, we devised four simple classification tools for non-medical personnel to evaluate the way. In addition, we devised four simple classification tools for non-medical personnel to evaluate the Kendall classification (S, M, L, and LL) and the Camper plane categories (S, M, and L) from standing Kendall classification (S, M, L, and LL) and the Camper plane categories (S, M, and L) from standing posture, and evaluated their inter-rater reliability. The results obtained from 62 photographs of lateral posture, and evaluated their inter-rater reliability. The results obtained from 62 photographs of lateral standing posture indicated that there was a significant trend of a dose-response relationship between standing posture indicated that there was a significant trend of a dose-response relationship between the Kendall postural types and the estimated PIs ( the Kendall postural types and the estimated PIs ( p p=0.06) , but there was no significant difference =0.06) , but there was no significant difference in multiple comparisons among them. The maximum inter-rater reliability (Kappa coefficient) of the in multiple comparisons among them. The maximum inter-rater reliability (Kappa coefficient) of the four simple classification tools was 0.41 (95% CI: 0.37-0.45) . From these results, we concluded that four simple classification tools was 0.41 (95% CI: 0.37-0.45) . From these results, we concluded that posture assessment using the Kendall postural types and the Camper plane categories cannot be used posture assessment using the Kendall postural types and the Camper plane categories cannot be used for estimating PI. Further improvement is warranted to enhance the inter-rater reliability of the four for estimating PI. Further improvement is warranted to enhance the inter-rater reliability of the four simple classification tools for practical use. simple classification tools for practical use.
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