Diminishing benefits of urban living for children and adolescents’ growth and development

Optimal growth and development in childhood and adolescence is crucial for lifelong health and well-being1–6. Here we used data from 2,325 population-based studies, with measurements of height and weight from 71 million participants, to report the height and body-mass index (BMI) of children and adolescents aged 5–19 years on the basis of rural and urban place of residence in 200 countries and territories from 1990 to 2020. In 1990, children and adolescents residing in cities were taller than their rural counterparts in all but a few high-income countries. By 2020, the urban height advantage became smaller in most countries, and in many high-income western countries it reversed into a small urban-based disadvantage. The exception was for boys in most countries in sub-Saharan Africa and in some countries in Oceania, south Asia and the region of central Asia, Middle East and north Africa. In these countries, successive cohorts of boys from rural places either did not gain height or possibly became shorter, and hence fell further behind their urban peers. The difference between the age-standardized mean BMI of children in urban and rural areas was <1.1 kg m–2 in the vast majority of countries. Within this small range, BMI increased slightly more in cities than in rural areas, except in south Asia, sub-Saharan Africa and some countries in central and eastern Europe. Our results show that in much of the world, the growth and developmental advantages of living in cities have diminished in the twenty-first century, whereas in much of sub-Saharan Africa they have amplified

Tree-Rings Reveal Accelerated Yellow-Cedar Decline with Changes to Winter Climate after 1980

Research Highlights: Yellow-cedar decline on the island archipelago of Haida Gwaii is driven by warm winter temperatures and low winter precipitation, which is caused by anthropogenic climate change and exacerbated by the positive phase of the Pacific Decadal Oscillation (PDO). Background and Objectives: Declining yellow-cedars are limited by physiological drought during the growing season, caused by freezing damage to fine roots through a complex pathway identified by research in Alaska. Given this, we hypothesized: (1) yellow-cedars on Haida Gwaii were limited by the winter climate. (2) Trees of different health classes were responding differently to climatic variation. (3) Changing climate-growth relations would vary among phases of the PDO. Materials and Methods: We sampled 15 stands exhibiting crown symptoms and developed three regional chronologies from trees that were healthy, had crown or tree-ring symptoms of decline, and trees that had died. We tested for growth responses to inter-annual and multi-decadal variation in climate among trees of different health statuses using correlation functions and wavelet analyses. Results: The three chronologies had similar patterns from the early 1500s to 1900s and responded to climate in the same way, with multi-decadal variability, and common narrow marker years. Climate-growth responses among trees of different health statuses diverged after the 1976/1977 switch in the PDO. Warm growing season temperatures facilitated the growth of trees in the healthy chronology. By contrast, growth of trees that showed symptoms of decline or had died was negatively associated with low winter precipitation. After 1986, growth of trees in the declining chronology decreased sharply and mortality increased, which is concurrent with the warmest winter temperatures and consistent with the root-freezing hypothesis from Alaska. Conclusions: Yellow-cedar decline is driven by climate change, exacerbated by the PDO. Warming winter temperatures, accelerated by anthropogenic climate change, have led to dieback and death of yellow-cedars, even with the temperate ocean-moderated climate of Haida Gwaii.Forestry, Faculty ofNon UBCForest and Conservation Sciences, Department ofReviewedFacultyOthe

The Size and Strength Development in Elite Youth Ice Hockey Players

Background: Ice hockey is a fast, physical sport that requires high levels of muscular strength, muscular endurance and agility. Objectives: This study was conducted to create a profile including: anthropometric measurement, muscular strength, muscular endurance, lower body jump height and distance, and agility characteristics for elite youth hockey players.  Methods: Pre-season off-ice testing results were retrospectively reviewed from a human performance database.  Variables included height, weight, body fat percentage, grip strength, push-ups/bench press, supine rows, the plank test, vertical jump, standing long jump, hip adductor and abductor strength, and the 5-10-5 shuttle, and. One-way ANOVAs (1group x 4 time) and Tukeys post-hoc tests were performed to determine changes in the immediately successive age group (p0.05). Results: Participants included male Bantam-(age: 13-14) and Midget-(age: 15-17) AAA ice-hockey players (n=260).  Age categories were grouped as 13 years old (yo)(n=75), 14 yo (n=70), 15 yo (n=58), and 16-17 yo (n=57).  Increases between successive age groups were observed in the following variables: weight (13, 14, 15 and 16-17 yo), height (13 and 14 yo), left and right grip strength (13, 14, 15, and 16-17 yo), bench press (15 and 16-17 yo), left and right hip abduction (14, 15, and 16-17 yo), and vertical and standing long jump (13, 14, and 15 yo). Total time for the 5-10-5 shuttle run test decreased from 13 to 14yo, and 14 to 15 yo. Conclusion: Changes with age in off-ice performance variables of elite amateur hockey players should be recognized, followed, and addressed during player development to maximize the potential for elite performance and reduce the risk of injury.  Keywords: Athletic Performance, Training, Physical Fitnes

The relationship among the age at menarche, anthropometric characteristics, and socio-economic factors in Bengali girls from Kolkata, India

Objectives: The aim of the study was to measure the causal effect of selected socio-economic factors and anthropometrical characteristics on the menarche occurrence. Methods: The sample consisted of 2195 Bengali girls (aged 7-21) from middle-class families, from Kolkata city, India. The age at menarche was recorded from the retrospective data and status quo method. The causal effect of anthropometric and socio-economic variables on menarche occurrence was estimated by the nonparametrical analysis of survival probability (survival random forest). Results: In the examined cohort menarche occurred, on average, at 11.8 years of age. The probability of menarche occurrence amplified with the increasing values of factors such as body mass index, height-for-age z-scores, number of family members, household rooms, and toilets, but decreased when expenditures increased. The relation maintained a similar pattern of causal effect with girls' age. Conclusions: A complex pattern of relationship among sexual development, physique, and socio-economic characteristics was defined. The tendency toward early menarche, along with the observed causal relationships indicate that the analyzed sample is nearing the characteristics and standards of living noted in other middle and even high-income countries in the world

The Size and Strength Development in Elite Youth Ice Hockey Players

Background: Ice hockey is a fast, physical sport that requires high levels of muscular strength, muscular endurance and agility. Objectives: This study was conducted to create a profile including: anthropometric measurement, muscular strength, muscular endurance, lower body jump height and distance, and agility characteristics for elite youth hockey players.  Methods: Pre-season off-ice testing results were retrospectively reviewed from a human performance database.  Variables included height, weight, body fat percentage, grip strength, push-ups/bench press, supine rows, the plank test, vertical jump, standing long jump, hip adductor and abductor strength, and the 5-10-5 shuttle, and. One-way ANOVAs (1group x 4 time) and Tukeys post-hoc tests were performed to determine changes in the immediately successive age group (p<0.05). Results: Participants included male Bantam-(age: 13-14) and Midget-(age: 15-17) AAA ice-hockey players (n=260).  Age categories were grouped as 13 years old (yo)(n=75), 14 yo (n=70), 15 yo (n=58), and 16-17 yo (n=57).  Increases between successive age groups were observed in the following variables: weight (13, 14, 15 and 16-17 yo), height (13 and 14 yo), left and right grip strength (13, 14, 15, and 16-17 yo), bench press (15 and 16-17 yo), left and right hip abduction (14, 15, and 16-17 yo), and vertical and standing long jump (13, 14, and 15 yo). Total time for the 5-10-5 shuttle run test decreased from 13 to 14yo, and 14 to 15 yo. Conclusion: Changes with age in off-ice performance variables of elite amateur hockey players should be recognized, followed, and addressed during player development to maximize the potential for elite performance and reduce the risk of injury.   Keywords: Athletic Performance, Training, Physical Fitnes