Journal of Physiological Anthropology最新文献

Background: Acute physical exercise, even at a very-light-intensity, potentiates prefrontal cortex activation and improves executive function. The underlying circuit mechanisms in the brain remain poorly understood, though we speculate a potential involvement of arousal-related neuromodulatory systems. Recently, our rodent study demonstrated that exercise, even at light-intensity, activates the midbrain dopaminergic neurons. Resting-state spontaneous eye blink rate is linked to brain-arousal neural circuits, and potentially to those modulated by dopaminergic system. We hypothesized that neural substrates linked to resting-state eye blink rate contribute to the cognitive impact of acute very-light-intensity exercise.

Method: We analyzed data from a previous study with a renewed focus on resting-state eye blink rate. Twenty-four healthy young adults completed both 10 min of cycling (very-light-intensity exercise: 30% peak oxygen uptake) and rest conditions. Resting-state eye blink rate and Stroop task performance were measured before and after both exercise and resting control.

Results: Results showed no significant differences in eye blink rate changes between conditions. However, correlation analyses revealed that exercise-induced changes in resting-state eye blink rate were significantly associated with individual variations in Stroop task performance enhancement.

Conclusion: Very-light-intensity exercise does not elicit a consistent increase in eye blink rate after exercise. This finding does not support the involvement of a blink increase-linked neural substrate in enhancing executive function through very-light-intensity exercise. However, resting-state eye blink rate that is altered by exercise is predictive of executive function enhancement levels; this may serve as a novel contactless biomarker for predicting exercise benefits for brain health and cognition.

Introduction: Low-intensity physical activity plays a key role in weight regulation, and reduced engagement in such activities is associated with rising obesity rates. This study explored the relationship between body fat distribution and exercise efficiency during low-intensity cycling, comparable to everyday life, focusing on adiposity in men and women.

Methods: Thirty participants (50% women and 50% men) underwent basal metabolic rate (BMR) measurements after an overnight fast. Following 500 ml water intake, they cycled at 60 rpm for 5 min at four intensities (20 W, 40 W, 60 W, 80 W), with respiratory parameters (i.e., energy expenditure (EE)) recorded using an indirect calorimeter system. Spearman correlations were used to assess the relationships among BMI, total body and trunk fat percentages, and delta efficiency (DE), which quantifies the energy cost associated with incremental work output during exercise.

Results: A linear increase in EE with increasing power output was observed in both men and women, with men showing a slightly higher EE across all power levels. The linear regression equations for power between 20 and 80 W were highly predictive, with R² values of 0.999 for men and 0.995 for women. Additionally, significant positive correlations were observed between BMI, fat percentage, trunk and limb fat percentages, and delta efficiency (DE) in women, explaining 45.7%, 34.7%, 34.1%, and 29.7% of the variance in DE, respectively. No significant correlations were found between these variables in men.

Conclusion: This study demonstrated that body fat distribution, particularly in women, is significantly associated with exercise efficiency during low-intensity cycling. These findings highlight the need for larger studies that incorporate gender-specific considerations in exercise and targeted interventions.

Background: Bioelectrical impedance analysis (BIA) is widely used as a convenient method of measuring body composition. The validity of the phase angle (PhA), impedance rate (IR), and resistance rate (RR) as indices of muscle quality using BIA has been suggested. This study aimed to investigate the relationship between these muscle quality indices and age, and to clarify their characteristics.

Methods: The appendicular muscle mass (AMM), AMM corrected for body mass index (AMM/BMI), PhA, IR, and RR were determined using BIA in 1376 Japanese individuals (532 males and 844 females) aged 15-95 years. The PhA was determined from a 50-kHz current, and the IR and RR were determined from the impedance and resistance ratios between the 250- and 5-kHz currents.

Results: AMM/BMI showed greater age-related changes than the other indices of muscle mass. Significant differences in PhA, IR, and RR were found for the whole body at age ≥ 50 years and for the lower limbs at age ≥ 30 years, compared to those in their 20 s. For the arms, age-related changes were small, and significant differences in PhA of females were only observed at aged ≥ 85 years, whereas significant differences in IR and RR were observed at aged ≥ 75 years, compared to those in their 20s.

Conclusion: These results suggest that although PhA, IR, and RR in the whole body and lower limbs showed age-related changes, the change in PhA in the upper body was small, especially in females. However, IR and RR in the upper limbs of females reflected age-related changes more than PhA.

This review aims to update our understanding of human cold adaptation. First, an overview of the thermoregulatory response to cold is provided, with some recent updates in human brown adipose tissue (BAT). Variation in BAT activity and multiorgan contributions to cold-induced thermogenesis were introduced. We found that individuals with less BAT activity rely more on shivering to compensate for less non-shivering thermogenesis (NST). The mechanisms of cold-induced vasoconstriction are summarized, including the role of arteriovenous anastomoses, adrenergic neural function, and inhibition of the nitric oxide vasodilator pathway. In addition, cold-induced vasodilation (CIVD) during cold immersion of the distal extremities is summarized with some recent updates in physiological mechanism. Furthermore, the cold shock response at the onset of cold immersion is introduced. Next, categorization of cold acclimatization/acclimation into habituation of shivering and metabolic and insulative adaptation are provided, with some recent updates. Especially, the rediscovery of human BAT has clarified metabolic acclimation, where increased NST replace shivering. Then, a greater CIVD response in populations in cold regions has been reported, whereas recent laboratory studies suggest no increase in CIVD after repeated cold exposure. To prevent cold injuries, individuals should not rely on habituation through repeated cold exposure. In addition, habituation to the cold shock response after repeated cold water immersion could help reduce the number of drownings. Furthermore, cross-adaptation between cold and nonthermal factors in the thermoregulatory response is summarized. Recent studies explored the relationship between exercise training and BAT activity, although this remains unresolved, depending on the exercise intensity and environmental conditions. The effects of exercise with cold exposure on the thermoregulatory response to cold are summarized in studies including divers working in cold water. We investigated the effect of exercise training in cold water, which resulted in increased muscle deoxygenation during submaximal exercise and greater anerobic power. Moreover, the effects of a hypoxic environment on cold adaptation are summarized. Elevated basal metabolism and higher distal skin temperature in highlanders could improve their cold tolerance. Finally, factors affecting cold adaptation are discussed. The type of cold adaptation may depend on the specific thermoregulatory responses repeated during the adaptation process.

Background: Prediction of sports success (sports talent) based on individual genetic characteristics is the main goal of sports genetics/genomics. Most often, markers of predisposition to speed-strength sports, or endurance, are single-nucleotide variants in various parts of DNA. One of the most studied variants is the C/T variant in the ACTN3 gene. The accumulated data on the association of this variant with success in various sports is sufficient to conduct a meta-analysis. The purpose of the present review is to analyze the prognostic utility of the data presented in the literature on molecular genetic markers of genetic predisposition to achieve outstanding sports results using the example of the C > T variant of ACTN3 (rs1815739).

Main body: A total of 42 studies were included in the analysis, with a total number of 41,054 individuals (of which 10,442 were in the athlete group and 30,612 in the control group). For each study included in the analysis, the agreement of genotype frequencies with Hardy-Weinberg equilibrium was tested, as well as the presence of an excess or deficit of heterozygotes. Prediction intervals for the overall effect size (OR-odds ratio) was estimated. Both in the subgroups of athletes and controls, a significant difference F_IS from zero was found, suggesting inbreeding or outbreeding, as well as a very wide 95% CI for F_IS. A meta-analysis was conducted for dominant, codominant, and recessive inheritance models. The obtained ORs and their 95% CIs were in the range of almost negligible values or have very wide CIs. The evaluation for the recessive model showed 95% PI for the OR lies between 0.74 to 1.92. Statistically, it does not differ from zero, which means that in some 95% of studies comparable to those in the analysis, the true effect size will fall in this interval.

Conclusion: Despite numerous attempts to identify genetic variants associated with success in elite sports, progress in this direction remains insignificant. Thus, no sports or sports roles were found for which the C > T variant of the ACTN3 gene would be a reliable prognostic marker for assessing an individual predisposition to achieve high sports performance. The results of the present meta-analysis support the conclusion that neutral gene polymorphism-from evolutionary or adaptive point of view-is not a trait that can be selected or used as a predictive tool in sports.

Humans have long pondered their genesis. The answer to the great question of where Homo sapiens come from has evolved in conjunction with biotechnologies that have allowed us to more brightly illuminate our distant past. The "Multiregional Evolution" model was once the hegemonic theory of Homo sapiens origins, but in the last 30 years, it has been supplanted by the "Out of Africa" model. Here, we review the major findings that have resulted in this paradigmatic shift. These include hominin brain expansion, classical insight from the mitochondrial genome (mtDNA) regarding the timing of the divergence point between Africans and non-Africans, and next-generation sequencing (NGS) of the Neanderthal and Denisovan genomes. These findings largely bolstered the "Out of Africa" model, although they also revealed a small degree of introgression of the Neanderthal and Denisovan genomes into those of non-African Homo sapiens. We also review paleogenomic studies for which migration route, north or south, early migrants to East Eurasia most likely traversed. Whichever route was taken, the migrants moved to higher latitudes, which necessitated adaptation for lower light conditions, colder clines, and pro-adipogenic mechanisms to counteract food scarcity. Further genetic and epigenetic investigations of these physiological adaptations constitute an integral aspect of the story of human origins and human migration to East Asia.

Background: Skin ageing is influenced by complex genetic factors. Various phenotypes such as wrinkling, pigmentation changes, and skin cancers have been linked to specific genetic loci. However, the underlying genetic mechanisms and pathways remain poorly understood. This systematic review and meta-analysis aims to summarise the genetic loci found to be associated with skin ageing phenotypes by published genome-wide association studies (GWAS) and candidate gene studies. We also evaluated the overall association of loci via meta-analysis and identified the association patterns to explore potential biological pathways contributing to skin ageing. The Web of Science, Embase, and PubMed databases were searched on January 2024 using specific exclusion criteria (e.g., study of non-human subjects, focus on skin diseases, or treatments) to identify relevant articles. There did not appear to be any significant publication bias observed across the all phenotypes.

Main body: A total of 48 studies were included, revealing 30 loci that were confirmed to be associated with skin ageing by multiple studies (e.g., AFG3L1P: odds ratio 1.133 95% confidence interval [1.044, 1.222]; BPIFA3: 1.859 [1.567, 2.151]; CLPTML1: 1.164 [1.0.99, 1.229]; CPNE7: 0.905 [0.852-0.958]; DEF8: 1.186 [1.042, 1.331]; IRF4: 1.260 [1.025, 1.495]; MYO16: 2.303 [1.697, 2.908]; PRDM16: 1.105 [1.084, 1.127]; RORA: 1.391 [1.206, 1.577]; SPG7: 0.922 [0.897, 0.947]; SPON1: 2.214 [1.204, 3.225]; SPTLC1: 1.464 [1.432, 1.495]; TYR: 1.175 [1.007, 1.343]). The lack of significance for many loci may be due to studies analysing different SNPs within the same locus, weakening the overall associations. Several loci were associated with specific phenotypic categories (e.g., skin colour related, skin cancer related, wrinkling and sagging related), suggesting shared biological pathways are involved in the pathogenesis of different skin ageing phenotypes. This pattern was also observed in several of the loci that do not have a significant overall association with skin ageing.

Conclusion: Despite significant heterogeneity among the included studies and the use of subjective visual methods for phenotype assessment, our review highlights the critical role of fundamental biological processes, such as development and cellular organisation, in skin ageing. Future research that targets the same SNP across multiple populations could strengthen the association of additional loci with skin ageing. Further investigation into these underlying biological processes would significantly advance our understanding of the pathogenesis of skin ageing phenotypes.

Background: Skin ageing takes on many different forms. Despite this diversity in skin ageing phenotypes, literature published to date is limited in scope, as many research studies either focus on one single phenotype or just a few specific phenotypes. Presently, phenotypes such as wrinkles, pigment spots, and photo-ageing are receiving most of the research attention. We therefore wonder whether the current discourse on skin ageing places a disproportionate amount of focus on a few selected phenotypes, leaving other skin ageing phenotypes underexplored.

Methods: In this cross-sectional study, we performed a broad assessment of forty-one signs of skin ageing and characterised the phenotypes that constituted key components of skin ageing. We also explored the interrelationship among forty-one skin ageing phenotypes using Spearman's Correlation and Principal Component Analysis.

Results: We analysed our study population, which is composed of 3281 ethnic Chinese participants from the Singapore/Malaysia Cross-sectional Genetics Epidemiology Study (SMCGES). The first ten principal components cumulatively explain 46.88% of the variance of skin ageing phenotypes in our study population. We discovered that the commonly discussed forms of skin ageing (i.e., wrinkles, pigmentation, and photo-ageing) only accounted for a small portion (24.39%) of the variance of all skin ageing phenotypes in our study population. Telangiectasia, a poor lip fullness, a lighter skin colour, xerosis, ephelides (freckles), ptosis of eyelids (droopy eyelids), eyebags, and a low eyebrow positioning were other key components of skin ageing, accounting for a further 22.49% of the variance of skin ageing phenotypes in our study population. We found that each of these ten skin ageing phenotypes characterises a key and important aspect of skin ageing. In this broad assessment of skin ageing, we first described the prevalence of forty-one signs of skin ageing and then characterised in detail both the prevalence and severity distribution of ten key skin ageing phenotypes.

Conclusions: We presented clear evidence that skin ageing is much more than just wrinkles, pigmentation and photo-ageing. The addition of telangiectasia, poor lip fullness, a lighter skin colour, xerosis, ephelides, ptosis of eyelids, eyebags, and a low eyebrow positioning added more dimensions to skin ageing phenotype presentations.

Background: The oxidative handicap hypothesis posits that testosterone-dependent traits, such as muscle mass and strength, may be costly to develop due to testosterone's pro-oxidative properties, leading to increased oxidative stress. This hypothesis suggests that only individuals with superior biological conditions can afford these costs. This study examines the oxidative handicap hypothesis, exploring the relationship between muscle mass or handgrip strength and oxidative stress markers in men.

Methods: Handgrip strength and muscle mass were measured in 179 men, with muscle mass assessed using bioelectrical impedance analysis (BIA) and handgrip strength measured using a hydraulic dynamometer. Serum testosterone levels and antioxidant capacity were measured. 8-OH-dG, 8-epi-PGF2α, and protein carbonyls were measured to evaluate oxidative stress level. Pearson's correlation and multivariate regression analyses were performed to examine the relationships between handgrip strength, muscle mass, and oxidative stress markers, controlling for age, serum testosterone levels, and antioxidant capacity.

Results: No significant correlations were found between handgrip strength and oxidative stress markers, even when controlling for muscle mass, antioxidant capacity, testosterone levels, and age.

Conclusions: The study's findings do not support the oxidative handicap hypothesis in the context of muscle parameters in men. The results suggest that testosterone-driven traits like handgrip strength or muscle mass may not necessarily incur oxidative stress costs in healthy young men, possibly due to effective compensatory antioxidant mechanisms. Factors like lifestyle, diet, and genetic predisposition, which were not controlled in this study, could also influence the observed outcomes and should be included in future research.

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.