American Journal of Human Biology最新文献

Introduction: University students experienced significant changes in their routines with the implementation of remote learning during Covid-19 pandemic, including increase in sedentary behavior (SB) time and ultra-processed foods (UPF's) consumption, which may have influenced changes in body mass index (BMI).

Objective: To evaluate the association between the variation in SB time and UPF's consumption with the variation in BMI, before and during the pandemic, in university students.

Methods: This is a cross-sectional study, conducted between November 2020 and February 2021, with students from a public university of Southeast of Brazil, who answered an online questionnaire with questions regarding to the period before and during the pandemic. SB was assessed through questions about time spent on TV and electronic devices. A score of the frequency of UPF's consumption was estimated based on the Brazilian Food Guide. Self-reported information on height and body mass was used to calculate BMI.

Results: The sample comprised 3390 university students, with an average age of 28.7 (± 10.0) years. Among them, 65.4% were undergraduates, and 66.9% were women. SB time, UPF score, and BMI increased significantly during the pandemic, compared to the previous period. In this population, there was a significant association between increased SB time (β = 0.06; SE = 0.01; p < 0.001) and UPF score (β = 0.08; SE = 0.01; p < 0.001) with an increase in BMI.

Conclusion: Changes in SB time and UPF score were associated with an increase in BMI before and during the COVID-19 pandemic in students from a Brazilian University.

Background: Little is known about the cardiorespiratory fitness (CRF)-cardiometabolic risk relationship in Latin American pediatric populations across different age/sex groups, especially when considering the potential effects of adiposity on the association. We evaluated cross-sectional associations between VO_2max and cardiometabolic risk variables (CMRV), and verified whether the associations were independent of adiposity markers in school-aged children and adolescents from Cali, Colombia.

Methods: The sample consisted of 1206 children aged 5-17 years. CMRV were fasting glucose, HDL and LDL cholesterol, triglycerides, systolic, and diastolic pressure. Logistic regressions were conducted for associations of age/sex-specific tertiles of VO_2max with age/sex-specific highest tertiles of CMRV (except HDL-C, lowest tertile) and a CMR cluster (> 2 CMRV in extreme tertiles), adjusting for socioeconomic stratum, and adiposity markers (BMI, body fat percentage, and waist circumference).

Results: Overweight/obesity ranged from 15% to 18% with no difference by sex. In children aged 5-11 years, high VO_2max (highest tertile vs. lowest) was inversely associated with the CMR cluster [Odds ratio (95% confidence interval): 0.18 (0.06-0.47), p < 0.05] independently of adjustment for any adiposity marker in boys but not in girls. In the age group of 12-17 years, there were initially significant VO_2max- CMR cluster and VO_2max- CMRV associations but attenuated by adiposity adjustment. In girls, high VO_2max was inversely associated with high systolic blood pressure regardless of adjustment for adiposity markers.

Conclusion: VO_2max is inversely associated with cardiometabolic risk, but adiposity influences the association. The adiposity-independent association among younger boys requires further research. Interventions to tackle cardiometabolic risk in childhood may primarily focus on reducing excess adiposity, and secondarily on improvement of CRF.

Objectives: Preschooler physical activity (PA) is vital for growth and development. The World Health Organization PA guidelines state preschoolers should achieve ≥ 180 min/day of Total PA (TPA) of which ≥ 60 min is moderate-to-vigorous PA (MVPA). A step/day recommendation to match these guidelines may be a more practical metric for caregivers to promote PA. The purpose of our investigation is to improve upon existing step recommendations by creating one for indoor-based activities, acknowledging where preschoolers spend most of their time, and various cut-points for PA.

Methods: In a laboratory study (Aim 1), a validated direct observation protocol was used to quantify preschooler PA intensity while performing indoor activities (n = 35). Actigraph GT3x accelerometers were placed on the waist, wrist, and ankle to measure step count. In a field study (Aim 2), habitual PA of 881 preschoolers (7113 valid days) via waist-worn accelerometers was used to assess the agreement between created guidelines (Aim 1) and other step recommendations with PA guidelines using Receiver Operating Characteristic and Area Under the Curve (ROC-AUC).

Results: In the laboratory study, calculated indoor step ranges were 6960-7440 (waist), 7200-8640 (wrist), and 7680-9120 (ankle) to align with existing PA guidance. In the field, the higher step guidelines (> 12 000) achieved very limited agreement, due to few preschoolers achieving this metric. The 6000 step/day guidelines had the highest agreement (AUCs: TPA: 0.637; MVPA: 0.751; TPA + MVPA: 0.761) with PA guideline.

Conclusions: When preschoolers are indoors, 6000 steps may be the minimum for adequate PA.

Objectives: The sex ratio at birth (SRB), calculated as male divided by total live births, is an important indicator of population health. Typically, male live births slightly outnumber female live births. Population events, including pandemics, can alter the SRB, with effects sometimes evident 9 months post-event, potentially due to changes in sexual behavior and/or stress levels. This study investigates the impact of the COVID-19 pandemic on the SRB in the Republic of Ireland.

Methods: Publicly available monthly live birth data for Ireland were obtained from the Central Statistics Office for the period 2015 to 2021. Time series analysis predicted the SRB for 2020 using data from 2015 to 2019, with comparisons made between observed and predicted values.

Results: In December 2020, 9 months after the March 2020 COVID-19 declaration, the observed SRB sharply fell to 49.44% (97.80 males for every 100 females), below the 95% prediction interval of 50.31% to 52.15%, significantly deviating from the expected male predominance. December 2020 also recorded the lowest average daily number of births (n = 145) in the study period.

Conclusion: The sharp decline in the SRB in December 2020, alongside the lowest birth count, suggests reduced sexual intercourse at the population level, particularly in March 2020, aligning with recommendations from Ireland's Health Service Executive (HSE). The HSE advocated precautionary measures such as limiting partnered sex in March 2020 to mitigate the spread of COVID-19. These findings highlight the pandemic's potential impact on population dynamics and stress the importance of SRB monitoring as a low-cost and readily available health indicator, especially during national crises.

Objectives: The digit ratio (2D:4D) is a possible marker of prenatal hormone exposure. The purpose of this study was to explore the relationships between digit ratio (2D:4D) and anthropometric indexes in Chinese children and adolescents.

Methods: This study is a cross-sectional study. A school-based survey among 685 children and adolescents aged 8-15 years were conducted by stratified cluster sampling. The length of index finger (2D) and ring finger (4D) of the left hand, height, sitting height (ST), weight, chest circumference (CC), waist circumference (WC), hip circumference (HC), and abdominal skinfold thickness (AST) were measured. Pearson correlation and multivariate linear regression were used to analyze associations between 2D:4D and above indexes.

Results: In girls, 2D:4D was positively related to WC, AST, waist-to-height (WHtR), waist-to-hip ratio (WHR) after adjusting for ages (p < 0.05). The WC, AST, WHtR, and WHR among girls with 2D:4D ≥ 1 were significantly higher than those among girls with 2D:4D < 1, respectively (p < 0.05). However, there was no correlations between digit ratio (2D:4D) and above anthropometric indexes in boys (p > 0.05).

Conclusions: The 2D:4D was related to anthropometric indexes in girls, which suggests that the maternal prenatal hormone exposure might be related to the anthropometric indexes of their female offspring.

Objectives: The impacts of stress on inflammation, although hypothesized, have not been thoroughly examined, especially in relation to social and environmental factors and particularly within Black populations. This study aims to explore the biological mechanisms of embodiment linking stress and health to understand physiological changes in the body's response to psychological stress in a Nigerian population. Through a multidisciplinary approach, this study queries the relationship between stress, cortisol, and salivary C-reactive protein (sCRP), a biomarker of inflammation, while also validating the use of sCRP as a potential and accurate stress indicator in the field.

Methods: In this cross-sectional study, 138 passive drool saliva samples (n_female = 89 n_male = 49) were collected and assessed for sCRP and cortisol levels in adults. Participants also completed a short demographic survey and, to measure psychological stress, the General Health Questionnaire 12 (GHQ-12). Relationships between sCRP and stress-related variables (i.e., cortisol, GHQ-12, and demographic data) were assessed using Spearman's correlations, simple regression, multivariable linear regression, and exploratory factor analysis.

Results: sCRP levels ranged from 20.57 to 6879.41 pg/mL across all samples, with significant differences between female and male participants. The GHQ-12 was not a significant predictor of sCRP variability. However, socio-demographic factors such as body mass index (BMI), age, self-reported sex, ethnic identity, and cortisol were significant predictors, collectively explaining 24%-27% of the variation in sCRP.

Conclusion: Socio-demographic predictors like BMI, age, sex, and particularly ethnic group experience in Nigeria encapsulate aspects of embodied stress, that significantly affect sCRP variability.

Background: This study aims to examine the relationship between resting vagal-related heart rate variability (HRV) parameters and heart rate (HR) with resting metabolic rate (RMR) and respiratory exchange ratio (RER) in young adults.

Methods: A total of 74 young adults (22 ± 2 years old, 51 women) were included in this cross-sectional study. HRV was assessed using a HR monitor, whereas RMR and RER were determined by indirect calorimetry.

Results: Linear regression analyses showed a positive association between HR and RER in women (standardized β = 0.384, p = 0.008), while negative associations were observed between vagal-related HRV parameters and RER in women (β ranged from -0.262 to -0.254, all p ≤ 0.042). No significant association was found between the abovementioned physiological parameters in men.

Conclusion: Here, we show that HR is positively associated with RER in young women but not in men, while vagal-related HRV parameters are inversely related to RMR, therefore suggesting a potential sexual dimorphism between cardiac rhythm and its relationship with markers of cardiometabolic health status.

Trial registration: ClinicalTrials.gov identifier: NCT02365129.