Journal of Physiological Anthropology最新文献

Background: Napping during night shifts is a countermeasure against fatigue and sleepiness, which both impact patient safety. However, there is insufficient evidence on how nurses nap, especially concerning their napping quality. This study explored night-shift napping and its associated factors among nurses, considering napping quantity and quality, to mitigate fatigue and sleepiness.

Methods: This month-long prospective observational study included 32 nurses working 16-h night shifts in a general ward. All nurses responded to questions on individual factors, while fatigue and sleepiness were checked four times during night shifts. Night-shift napping was measured using a wearable device and classified into six groups: time in bed [TIB] > 180 min and sleep efficiency [SE] ≥ 70%, TIB > 180 min and SE < 70%, TIB 120-180 min and SE ≥ 70%, TIB 120-180 min and SE < 70%, TIB < 120 min and SE ≥ 70%, and TIB < 120 min and SE < 70%.

Results: Most nurses (81.2%) worked four night shifts per month, and 105 night shifts in which nurses intended to nap were analyzed. The two nap conditions (TIB 120-180 min and SE ≥ 70%, TIB > 180 min and SE ≥ 70%) were not worse than other nap conditions in fatigue and sleepiness at the end of the night shift and change in fatigue from the start to the end of the night shift. Sleep reactivity, pre-nap time on electronic devices, and prophylactic naps taken before the night shift were each the common factors related to napping for TIB ≥ 120 min and SE ≥ 70%.

Conclusions: Nurses working long night shifts should consider both sufficient napping quantity and good napping quality. We suggest aiming for a TIB of at least 120 min and a SE of at least 70% to mitigate fatigue and sleepiness at the end of a night shift. Assessing sleep reactivity, pre-nap time on electronic devices, and prophylactic naps may be useful in achieving both quantity and quality effectively. Nurses and their managers should have a better understanding of napping and consider strategically taking naps during night shifts.

Background: Muscle architecture is closely related to muscle function. Increased knowledge of growth changes in muscle architecture will provide insights into the development of human movements and sports performance during the growth period. However, it is unclear how the muscle architecture of the medial gastrocnemius (MG) grows. This study examined the effects of growth on the muscle architecture of MG.

Methods: The brightness-mode ultrasonography technique was used to measure the muscle thickness, pennation angle, and fascicle length of MG in 146 Japanese boys aged to 6.2 - 17.9 years. The relative muscle thickness was calculated by dividing the absolute muscle thickness by body mass^1/3. The years from the age at peak height velocity were estimated for each participant, and used as the maturity index. A simple regression analysis was performed for the two variables in the full age range, as well as separately for the 5 - 12 years and 12 - 19 years subgroups. RESULTS AND CONCLUSION: The maturity index and chronological age were positively correlated with the relative muscle thickness, pennation angle, and fascicle length of MG. Subgroup analyses showed that chronological age was significantly correlated with the pennation angle, fascicle length, and absolute muscle thickness, except for the pennation angle of the 5 - 12 years subgroup. The present results indicate that muscle hypertrophy and elongation of fascicle length occur with growth. Our findings also suggest that the growth changes in pennation angle of MG differ between pre-adolescence and adolescence.

Background: Circulating fatty acid-binding protein 4 (FABP4) influences cardiovascular disease and glucose metabolism. Acute aerobic exercise increases circulating FABP4 concentrations, but the factors underlying this effect in humans are unclear. We investigated the effect of exercise duration on circulating FABP4 concentrations in healthy men.

Methods: This randomized crossover study enrolled healthy young men randomly assigned to two trials, short-duration (SE) and long-duration (LE) aerobic exercises trials. Both involved acute aerobic exercise followed by 60 min of bed rest. The exercise intensity was the same (40% peak oxygen uptake); however, the duration was 40 and 70 min for the SE and LE trials, respectively. Venous blood samples were collected to measure hormones, metabolites, and FABP4 concentrations.

Results: Twelve healthy young men completed both trials. Changes in hormone levels did not differ significantly between the SE and LE trials (p > 0.05). However, the circulating FABP4 concentration increased significantly only in the LE trial immediately after exercise (p = 0.018). It increased significantly 30-60 min post-exercise in both the SE and LE trials (p < 0.018), with the extent of the increase being significantly higher in the LE trial than in the SE trial (p < 0.001). In each trial, the total incremental area under the curve of circulating FABP4 concentration was significantly positively correlated with body fat percentage (SE trial: r_s = 0.699, p = 0.019; LE trial: r_s = 0.643, p = 0.024).

Conclusion: Our findings suggest that exercise duration is associated with the magnitude of increased FABP4 secretion into the blood circulation. Body fat accumulation may also be involved in the magnitude of FABP4 secretion induced by acute aerobic exercise.

Trial registration: The study was pre-registered with the University Hospital Medical Information Network Center (UMIN), a clinical trial registration system (ID: UMIN000051068).

The purpose of this study was to investigate the effects of elevated core temperature by exposure to heat stress vs. heat exposure without elevated core temperature (mean skin temperature only) in addition to mental fatigue on aerobic exercise capacity in the heat. Seven highly trained athletes completed two experimental conditions: elevation in core and skin temperatures (hyperthermia: HYP), and skin temperatures (SKIN). Participants performed the AX-Continuous Performance Task and Stroop Task to induce mental fatigue during a warm water immersion at 40 °C (HYP) and a passive seated heat exposure in a climatic chamber at 35 °C and 60% relative humidity (SKIN) for 45 min before exercise. Thereafter, participants performed running trial at 80% maximal oxygen uptake until voluntary exhaustion in the same chamber as the SKIN. Exercise time to exhaustion was significantly shorter in the HYP trial (538 ± 200 s) than in the SKIN trial (757 ± 324 s). Rectal temperature at the end of tasks in the HYP trial increased by 0.86 ± 0.26℃ and was significantly higher (37.69 ± 0.18℃) than that of the SKIN trial (36.96 ± 0.13℃), albeit no significant differences in mean skin temperature. Self-reported mental fatigue using visual analog scale was significantly higher after tasks in both trials, but no significant difference between trials was found. Throughout the trial, salivary cortisol concentration and perceptual responses were not affected by hyperthermia. This study demonstrated that a combination of high core temperature and mean skin temperature, and mental fatigue limit aerobic exercise capacity in highly trained athletes in hot environments compared with heat exposure without an elevation of core temperature.

Pentosidine is representative of the cross-linked structure of advanced glycation end products (AGEs) and has been suggested as a biomarker to assess bone and muscle quality. As studies on pentosidine in young adult men remain limited, we aimed to clarify the associations of urinary pentosidine with musculoskeletal status and physical performance in young men. Participants in this study comprised 32 men (age range: 19-39 years). Anthropometric measurements (body composition by InBody 430; stiffness index by ultrasound), muscle performance (grip strength by dynamometer, thigh muscle thickness by ultrasound), physical performance (functional reach test, 30-s chair stand test, and timed up and go test), and urinary biomarkers (pentosidine, N-telopeptide of type I collagen, and creatinine) were measured. In partial correlation analysis adjusted for age and height, higher urinary pentosidine levels were significantly associated with lower fat-free mass index (rho = - 0.368, p = 0.046), grip strength (rho = - 0.433, p = 0.017), rectus femoris thickness (rho = - 0.393, p = 0.032), and anterior thigh thickness (rho = - 0.416, p = 0.022), and a marginally inverse correlation was noted between urinary pentosidine levels and functional reach test (rho = - 0.327, p = 0.078). Our findings suggest that pentosidine correlates inversely with a few muscle and physical performance indicators. Pending future validations, urinary pentosidine may be a biomarker of AGEs in young men.

Background: The efficacy of whole-body cryostimulation (WBC) may be influenced by individual characteristics. The aim of this study is to determine the optimal exposure time required to reach the analgesic threshold of 13.6 °C, which has been proposed to be a target temperature to be reached at skin level. Our objective is also to follow the skin temperature changes during and after WBC considering the participants body mass index (BMI).

Methods: Thirty healthy men were assigned into 2 groups based on their BMI [normal weight (n = 15; BMI = 21.53 ± 1.63 kg·m^-2) and overweight (n = 15; BMI = 27.98 ± 1.16 kg·m^-2)]. In a random order, each participant experienced a 4-min WBC exposure, as well as a control session with no cold exposure. Skin temperature was measured using a thermal imaging camera during and after cold exposure.

Results: Normal weight participants reached the threshold in 4 min, whereas overweight participants reached it in 3 min 30 s. Following WBC, a rapid mean skin temperature (MsT°) increase was observed for both groups, immediately after exposure. However, after 30 min, MsT° remained significantly lower than at baseline.

Conclusion: Our findings suggest that appropriate WBC dosage may differ according to BMI. Understanding the impact of such variable on cold exposure outcomes can help to optimize WBC treatments and maximize potential benefits.

Background: Heart rate is one of the most crucial vital signs and can be measured remotely using microwave Doppler radar. As the distance between the body and the Doppler radar sensor increases, the output signal weakens, making it difficult to extract heartbeat waveforms. In this study, we propose a new template-matching method that addresses this issue by simulating Doppler radar signals. This method extracts the heartbeat waveform with higher accuracy while the participant is naturally sitting in a chair.

Methods: An extended triangular wave model was created as a mathematical representation of cardiac physiology, taking into account heart movements. The Doppler radar output signal was then simulated based on this model to automatically obtain a template for one cycle. The validity of the proposed method was confirmed by calculating the PPIs using the template and comparing their accuracy to the R-R intervals (RRIs) of the electrocardiogram for five participants and by analyzing the signals of eight participants in their natural state using the mathematical model of heart movements. All measurements were conducted from a distance of 500 mm.

Results: The correlation coefficients between the RRIs of the electrocardiogram and the PPIs using the proposed method were examined for five participants. The correlation coefficients were 0.93 without breathing and 0.70 with breathing. This demonstrates a higher correlation considering the long distance of 500 mm, and the fact that body movements were not specifically restricted, suggesting that the proposed method can successfully estimate RRI. The average correlation coefficients, calculated between the Doppler output signals and the templates for each of the eight participants, exceeded 0.95. Overall, the proposed method showed higher correlation coefficients than those reported in previous studies, indicating that our method performed well in extracting heartbeat waveforms.

Conclusions: Our results indicate that the proposed method of remote heart monitoring using microwave Doppler radar demonstrates higher accuracy in estimating the RRI of the electrocardiogram while at rest sitting in a chair, and the ability to extract the heartbeat waveforms from the measured Doppler output signal, eliminating the need to create templates in advance as required by conventional template matching methods. This approach offers more flexibility in the measurement environment than conventional methods.

Background: Maternal preconception overweight status has been reported to be associated with an increased risk of overweight offspring. However, there are no published population-based studies on the association between maternal preconception weight and offspring body fat measured by dual-energy X-ray absorptiometry (DXA). The present population-based retrospective cohort study aimed to examine the association between maternal weight at conception and offspring body fat measured by DXA.

Methods: The source population consisted of 5th-grade students (1244 students aged 11 years) registered at 8 municipal elementary schools in Kitakata, Fukuroi, Hamamatsu, and Himeji in Japan. The present analyses included 964 participants who provided complete information. Maternal body mass index (BMI) at conception was calculated using records in the Mother and Child Health Handbook (MCHH). Offspring body fat at age 11 years was measured with the same QDR-4500A DXA instrument in a mobile test room that was brought to each school. With regard to the prediction of excess fat in offspring, the area under the curve (AUC) calculated with receiver operating characteristic curve analysis was used to quantify the diagnostic accuracy of maternal BMI at conception.

Results: Adjusted odds ratios for excess body fat in offspring of the overweight mother group (odds ratios, 4.93 to 15.32) were significantly higher than those in the non-overweight mother group. For the prediction of excess offspring fat, AUCs and 95% confidence intervals for maternal BMI at conception were greater than 0.5.

Conclusion: Maternal overweight status at conception might be a risk factor for excess body fat in offspring. Maternal BMI values calculated using MCHH data have the potential to distinguish between the presence and absence of excess fat in the next generation.

Background: Tibetan highlanders have adapted to hypoxic environments through genetic mechanisms that avoid hemoglobin concentration increases and prevent polycythemia. Recently, sex differences in hemoglobin dynamics with age have been reported among Tibetan highlanders living in Tsarang. Additionally, concerns have been raised that dietary changes associated with modernization may increase the risk of polycythemia and lifestyle-related diseases among Tibetan highlanders. However, the relationship between genetic polymorphisms and the risk of lifestyle-related diseases in Tibetan highlanders has been investigated in only a few regions. This study aims to elucidate whether polymorphisms in genes related to hypoxic adaptation are associated with the incidence of lifestyle-related diseases and polycythemia and whether these polymorphisms affect hemoglobin dynamics in the residents of Tsarang, Mustang, Nepal.

Methods: Health checkup data from individuals living in Tsarang in Mustang District, Nepal, collected in 2017, were used to determine the prevalence of obesity, hypertension, diabetes, hypoxemia, and polycythemia. DNA was extracted from whole-blood samples, and data for the single-nucleotide polymorphisms (SNPs) rs13419896 (EPAS1), rs12619696 (EPAS1), and rs2790859 (EGLN1) were obtained using real-time PCR. The health checkup data were statistically analyzed to determine the associations of these diseases with polymorphisms in genes related to hypoxic adaptation.

Results: A total of 168 participants, comprising 78 males and 90 females, were included in the final analysis. In terms of the prevalence of each disease, only the prevalence of polycythemia significantly differed between sexes (p < 0.01). Additionally, among the three analyzed SNPs, significant sex differences in genotype frequency were observed for rs13419896 and rs2790859. For rs2790859 in females, Tibetan highlanders with the adaptive genotype had a significantly lower incidence of polycythemia (p < 0.01) and significantly lower hemoglobin concentrations (p < 0.01).

Conclusions: This study revealed that there are sex differences in the genotype frequency of gene-related hypoxic adaptations among the residents of Tsarang. The findings also suggested that the rs2790859 polymorphism might be involved in the recent incidence of polycythemia among Tsarang residents. If the frequency of non-Tibetan genotypes increases due to intermixing with other populations in the Mustang District, polycythemia may emerge as a modern disease. It is essential to continue investigating the health status of Mustang residents to elucidate various aspects of hypoxic adaptation and disease susceptibility.