Physical growth of St. Lawrence Island Eskimos: body size, proportion, and composition

Axial and appendicular body proportions for evaluation of limb and trunk asymmetry

Background and purpose - When children with irregular body proportions or asymmetric limbs present, it may be unclear where the pathology is located. An improved understanding of the clinical ratio between upper extremity, lower extremity, and spine length may help elucidate whether there is disproportion between the trunk and limbs, and whether there is a reduction deficit of the shorter limb rather than hypertrophy of the longer limb. Patients and methods - We used the Brush Foundation study of child growth and development, which was a prospective, longitudinal study of healthy children between the 1930s and the 1950s, and we collected serial clinical measurements for 290 children at 3,326 visits. Children ranged from 2 to 20 years of age during the study period. Linear and quadratic regression were used to construct nomographs and 95% prediction intervals for anthropometric body proportions. Results - The maximum anterior superior iliac spine height to sitting height ratio occurred at 12.4 years in females and at 14.17 years in males. Overall, the ratio of arm length to sitting height was 0.76 (SD 0.06), the ratio of arm length to anterior superior iliac spine height was 0.76 (SD 0.03), and the ratio of anterior superior iliac spine height to sitting height was 0.98 (SD 0.13). When comparing ratios between arm length, anterior superior iliac spine height, and sitting height, the smallest variance between appendicular proportions was found in the arm length to anterior superior iliac spine height ratio. Interpretation - We recommend comparisons between total arm length and anterior superior iliac spine height to distinguish limb reduction deficits from hemi-hypertrophy, with sitting height being used only if combined upper and lower extremity discrepancy is noted.

Body mass index may overestimate the prevalence of overweight and obesity among the Inuit

Body mass index (BMI) is a widely used body weight classification system but has known limitations, and may need to be adjusted for sitting height in order to be useful as an indicator of health risks in special populations. Data confirm that Inuit and Far East Asians have shorter legs and relatively higher sitting heights compared with all other populations. Using standing height alone to calculate the BMI may overestimate the number of individuals that are overweight and obese, and at risk for type 2 diabetes mellitus and cardiovascular disease among the Inuit. Measuring sitting height allows for the calculation of a sitting height-to-standing height ratio (SH/S) which can be used to correct the observed BMI. Incorporating sitting height measurements into health research could help formulate Inuit-specific screening guidelines.

Does sitting height ratio affect estimates of obesity prevalence among Canadian Inuit? Results from the 2007-2008 Inuit Health Survey

OBJECTIVES

High sitting height ratio (SHR) is a characteristic commonly associated with Inuit morphology. Inuit are described as having short leg lengths and high trunk-to-stature proportions such that cutoffs for obesity derived from European populations may not adequately describe thresholds of disease risk. Further, high SHR may help explain the reduced impact of BMI on metabolic risk factors among Inuit relative to comparison populations. This study investigates the relationship between SHR and body mass index (BMI) in Inuit.

METHODS

Subjects are 2,168 individuals (837 males and 1,331 females) from 36 Inuit communities in the Canadian Arctic. Mean age is 42.63 ± 14.86 years in males and 41.71 ± 14.83 years in females. We use linear regression to examine the association between age, sex, height, sitting height, SHR, waist circumference (WC), and BMI. We then evaluate the efficacy of the relative sitting height adjustment as a method of correcting observed BMI to a population-standardized SHR.

RESULTS

Mean BMI is significantly higher than among non-Inuit Canadians. Obesity prevalence is high, particularly among Inuit women. In the regression, only age and WC are significant predictors of BMI. While SHR is significantly greater than that of the US population, there is substantial agreement between overweight and obesity prevalence using observed and corrected BMI.

CONCLUSIONS

We find no consistent relationship between SHR and BMI and suggest the unique anthropometric and metabolic profile observed in Inuit arise from factors not yet delineated. More complex anthropometric and imaging studies in Inuit are needed.

Are the circumpolar Inuit becoming obese?

This paper reviews the ethnographic, historical, and recent epidemiological evidence of obesity among the Inuit/Eskimo in the circumpolar region. The Inuit are clearly at higher risk for obesity than other populations globally, if "universal" measures based on body mass index (BMI) and waist circumference and criteria such as those of WHO are used. Inuit women in particular have very high mean waist circumference levels in international comparisons. Given the limited trend data, BMI-defined obesity is more common today than even as recently as three decades ago. Inuit are not immune from the health hazards associated with obesity. However, the "dose-response" curves for the impact of obesity on metabolic indicators such as plasma lipids and blood pressure are lower than in other populations. Long-term, follow-up studies are needed to determine the metabolic consequences and disease risks of different categories of obesity. At least in one respect, the higher relative sitting height among Inuit, obesity measures based on BMI may not be appropriate for the Inuit. Ultimately, it is important to go beyond simple anthropometry to more accurate determination of body composition studies, and also localization of body fat using imaging techniques such as ultrasound and computed tomography. Internationally, there is increasing recognition of the need for ethnospecific obesity criteria. Notwithstanding the need for better quality epidemiological data, there is already an urgent need for action in the design and evaluation of community-based health interventions, if the emerging epidemic of obesity and other chronic diseases are to be averted.

Variation in Human Body Size and Shape

▪ Abstract  Evolutionary trends in human body form provide important context for interpreting variation among modern populations. Average body mass in living humans is smaller than it was during most of the Pleistocene, possibly owing to technological improvements during the past 50,000 years that no longer favored large body size. Sexual dimorphism in body size reached modern levels at least 150,000 years ago and probably earlier. Geographic variation in both body size and shape in earlier humans paralleled latitudinal clines observed today. Climatic adaptation is the most likely primary cause for these gradients, overlain in more recent populations by nutritional effects on growth. Thus, to distinguish growth disturbances, it is necessary to partition out the (presumably genetic) long-term differences in body form between populations that have resulted from climatic selection. An example is given from a study of Inupiat children, using a new index of body shape to assess relative body mass.

Cultural competency matters

Canada is one of the most multi‐cultural countries in the world. Because of this, a wide variety of ethnic, cultural and personal differences exists. These factors affect patients, their families and health care professionals. Nurses in particular need to be aware of these differences since they are the people most likely to interact closely with patients and all others who are associated with a particular case. Addresses some of those common differences and provides an awareness for professionals who deal with these issues.

Adipose tissue in human infancy and childhood: an evolutionary perspective

Humans diverge from most mammals, including nonhuman primates, by depositing significant quantities of body fat in utero and are consequently one of the fattest species on record at birth. While explanations for the fat layer of human neonates have commonly assumed that it serves as insulation to compensate for hairlessness, empirical support for this hypothesis is presently weak. Whether the tissue's abundance at birth and growth changes in adiposity during infancy and childhood might be explained in light of its role as energy buffer has not been assessed, and this possibility is explored through development of a model of fat function and growth centered on two related hypotheses. The first is that the greater adiposity of human neonates is at least partially explainable as an accompaniment of the enlarged human brain, which demands a larger energy reserve to ensure that its obligatory needs are met when the flow of resources from mother or other caretakers is disrupted. The second is that age-related changes in the likelihood of experiencing such disruption have influenced the pattern of investment in the tissue, reflected today in peak adiposity during infancy and a decline to a leaner childhood period. Nutritional disruption is common at birth and until lactation is established, during which time human newborns survive from fats deposited prenatally, suggesting one possible explanation for the early onset of fat deposition. At weaning, the transition from breast milk to supplemental foods and the parallel transition from maternal to endogenous immune protection interact to increase the frequency and impact of nutritional disruption, and this may help explain why newborns devote roughly 70% of growth expenditure to fat deposition during the early postnatal months. Evidence is presented that fat stores are mobilized during infections, hinting at one possible mechanism underlying the association between nutritional status and infectious morbidity and mortality among infants in nutritionally stressed human populations. Consistent with the proposed hypothesis, well-fed infants acquire peak fat reserves by an age of peak prevalence of malnutrition, infectious disease, and fat reserve depletion in less-buffered contexts, and childhood--characterized by minimal investment in the tissue--is a stage of reduced risk of energy stress. The model presented here foregrounds energy storage in adipose tissue as an important life-history strategy and a means to modify mortality risk during the nutritionally turbulent period of infancy.

Anthropometric measurements and body proportions among Chinese children

There are significant racial differences in body proportions. Such data are not readily available for Chinese children. This article reports a cross section study of body proportions of 2193 Hong Kong Chinese children, ages 4 to 16 years, with equal gender distribution. Standing height, sitting height, and arm span were measured with standard equipment and methodology. Lower segment height was calculated as the difference between standing height and sitting height. Statistical analysis of the results showed a high linear correlation of the standing height with arm span, sitting height, and lower segment height, with a correlation coefficient ranging from 0.965 to 0.983 for both genders. When expressed as the ratio of standing height to arm span, the value was relatively constant and changed only linearly from 1.03 to 1 in girls and 1.03 to 0.98 in boys ages 4 to 16 years. The ratio of sitting height to lower segment height varied from a mean of 1.4 to 1.14 in boys and 1.36 to 1.18 in girls ages 4 to 16 years. The Chinese children were found to have a proportional limb segmental length relative to the trunk that differed significantly from the proportionally longer limbs in whites and blacks.

Growth and fitness of Canadian inuit: Secular trends, 1970-1990

The growth and development of Inuit children and adolescents living in the high arctic (Igloolik, NWT, 69°40' N, 81°W) has been surveyed crosssectionally and semilongitudinally on three occasions during a period of rapid acculturation: 1969-1970, 1979-1980, 1989-1990. Recruitment declined from 85% (1969-1970) to 63% (1989-1990) of eligible subjects, in the most recent survey a total of 91 males and 65 females. Secular trends in the community have included a change from nomadic to settled life, improved access to health care, reduction of average family size, a progressive shift from country to market foods, the introduction of a 12-grade school, and a progressive reduction of habitual physical activity with the advent of television and video programs. The stature of the youngest students has tended to increase by ∼1cm/decade, possibly as a consequence of dietary changes and resultant earlier maturation, but the stature of older adolescents has tended to decrease, possibly as a consequence of spinal trauma sustained during high-speed snowmobile operation. In the boys, the estimated onset of rapid pubertal growth has advanced from an age of 13-14 to 12-13 years, and in the girls, the period of rapid growth is now already established at 11 years. Over the 20 years of observation, skinfold thicknesses at any given age have increased, handgrip and knee extension forces have diminished, and relative aerobic power has also decreased. In consequence, the current generation of Inuit children are no more fit than their sedentary peers in southern Canada. © 1994 Wiley-Liss, Inc.

Secular trends and the pattern of growth in arctic populations

Examinations of growth patterns in Arctic populations suggest that Inuit/Inupiat (Eskimo) children display a unique pattern relative to European or continental U.S. children. This pattern--high weight for height--becomes established early in life and it has existed for as long as researchers have Inuit or Inupiat data. This paper will examine the growth pattern relative to the NCHS reference standard, using recent data from the Arctic and several indices combining height and weight. Of particular concern will be the persistence of this pattern in the face of secular trends in growth that have occurred over the past 50 years. Trends for height increase have been greater than those for weight but weight for height still remains well above the 50th percentile of the U.S. reference for these Arctic groups.