Socio-demographic predictors of sleep complaints in indigenous Siberians with a mixed economy.

OBJECTIVES: Socio-demographic indicators closely relate to sleep in industrialized populations. However we know very little about how such factors impact sleep in populations undergoing industrialization. Within populations transitioning to the global economy, the preliminary evidence has found an inconsistent relationship between socio-demographics and sleep complaints across countries and social strata. MATERIALS AND METHODS: Surveys were conducted on a sample of rural Sakha (Yakut) adults (n = 168) during the autumn of 2103 to assess variation in socio-demographics and sleep complaints, including trouble sleeping and daytime sleepiness. Socio-demographic variables included age, gender, socioeconomic measures, and markers of traditional/market-based lifestyle. We tested whether the socio-demographic variables predicted sleep complaints using bivariate analyses and multiple logistic regressions. RESULTS: Trouble sleeping was reported by 18.5% of the participants and excessive daytime sleepiness (EDS) by 17.3%. Trouble sleeping was significantly predicted by older age, female gender, and mixing traditional and market-based lifestyles. EDS was not significantly predicted by any socio-demographic variable. DISCUSSION: These findings support the few large-scale studies that found inconsistent relationships between measures of socioeconomic status and sleep complaints in transitioning populations. Employing a mix of traditional and market-based lifestyles may leave Sakha in a space of vulnerability, leading to trouble sleeping.

Do physical activity and sedentary behavior relate to cardio-metabolic risk factor clustering in indigenous Siberian adults?

OBJECTIVES: To investigate whether having multiple risk factors for cardio-metabolic disease is associated with objectively measured physical activity or sedentary behavior within a sample of Yakut (Sakha) of Siberia. METHODS: This cross sectional study involved 63 Yakut adults (32 men) who were measured for cardio-metabolic risk factors. Free living physical activity and sedentary behavior were calculated from waist accelerometry. Correlations and t-tests were used to assess the relationship between moderate-vigorous physical activity (MVPA), sedentary behavior (SB), and individual risk factors and clustering of risk factors. RESULTS: These Yakut were physically active, with 54.4% spending at least 30 min in MVPA, with men being more active than women and women having less favorable cardio-metabolic profiles. These Yakut spent about 7.5 h in SB a day. SB was not related to cardio-metabolic risk factors. MVPA was significantly and negatively related to waist circumference and risk factor clustering in men and the total sample. MVPA was not related to women's risk factors. CONCLUSIONS: Objectively measured physical activity was related to lower risk of cardio-metabolic risk factor clustering within this sample of Yakut men, but not women. SB was not related to cardio-metabolic indicators. Physical activity may contribute to a reduction in clustering of metabolic risk factors within indigenous circumpolar populations.

Maternal short stature does not predict their children's fatness indicators in a nutritional dual-burden sample of urban Mexican Maya.

The co-existence of very short stature due to poor chronic environment in early life and obesity is becoming a public health concern in rapidly transitioning populations with high levels of poverty. Individuals who have very short stature seem to be at an increased risk of obesity in times of relative caloric abundance. Increasing evidence shows that an individual is influenced by exposures in previous generations. This study assesses whether maternal poor early life environment predicts her child's adiposity using cross sectional design on Maya schoolchildren aged 7-9 and their mothers (n = 57 pairs). We compared maternal chronic early life environment (stature) with her child's adiposity (body mass index [BMI] z-score, waist circumference z-score, and percentage body fat) using multiple linear regression, controlling for the child's own environmental exposures (household sanitation and maternal parity). The research was performed in the south of Merida, Yucatan, Mexico, a low socioeconomic urban area in an upper middle income country. The Maya mothers were very short, with a mean stature of 147 cm. The children had fairly high adiposity levels, with BMI and waist circumference z-scores above the reference median. Maternal stature did not significantly predict any child adiposity indicator. There does not appear to be an intergenerational component of maternal early life chronic under-nutrition on her child's obesity risk within this free living population living in poverty. These results suggest that the co-existence of very short stature and obesity appears to be primarily due to exposures and experiences within a generation rather than across generations.

Objectively measured physical activity and sedentary behaviour of Yakut (Sakha) adults.

BACKGROUND: Circumpolar regions are undergoing social and economic transition, which often corresponds to a behavioural transition. Yet, physical activity and sedentary behaviour are rarely objectively measured within these groups. AIM: This study aimed to characterize objectively measured physical activity and sedentary behaviour in a sample of indigenous Siberians. SUBJECTS AND METHODS: Yakut (Sakha) adults (n = 68, 32 men) underwent anthropometry, interviews and wore a triaxial accelerometer for two days. Time spent in moderate-to-vigorous physical activity (MVPA) or sedentary behaviour was calculated using a single axis and also all three axes. RESULTS: Men spent significantly more time in MVPA than women, although no sex difference was found in sedentary behaviour. Participants were far more active and less sedentary when classified using all three axes (vector magnitude) than a single axis. Television viewing time significantly related to sedentary behaviour in men only. CONCLUSION: The Yakut have gender differences in amount and predictors of physical activity and sedentary behaviour. Triaxial accelerometry is more sensitive to daily physical activity in free living populations than single axis.

Fat free mass explains the relationship between stunting and energy expenditure in urban Mexican Maya children.

BACKGROUND: Childhood stunting has been associated with an increased risk of obesity in adulthood, but the causes are unclear. This study hypothesizes that stunting significantly reduces both resting and activity energy expenditure. AIM: To assess and describe energy expenditure of low socio-economic Maya children and to determine whether stunting is independently related to energy expenditure after controlling for lean mass. SUBJECTS AND METHODS: Thirty-three urban Maya children, 17 boys, aged 7-9 years, living in Merida, Mexico, were measured for height, weight and bioelectrical impedance analysis (BIA). Body composition was estimated from BIA. Energy expenditure was measured for one week using the Actiheart (combined heart rate and accelerometer). RESULTS: Stunting (height-for-age below the 5(th) percentile of NHANES III based references) affected 35% of these physically active children. Using multiple linear regression analysis, greater lean body mass predicted higher resting and activity energy expenditure. Stature was not a significant predictor of resting energy expenditure. A lower height-for-age z-score, but not stunting as a categorical variable, significantly predicted lower activity energy expenditure. CONCLUSION: The hypothesis that stunting reduces total energy expenditure (resting + active) in children is not supported. Rather, children with shorter stature and less lean body mass have lower total energy expenditure. Complex interactions between body size, body composition, and metabolic activity appear to elevate the risk for later life obesity in these Maya children.

How useful is BMI in predicting adiposity indicators in a sample of Maya children and women with high levels of stunting?

OBJECTIVES: Body mass index (BMI) is used frequently to estimate adiposity levels in children and adults. However, the applicability of BMI to populations with high levels of stunting has been questioned. Stunted people can have disproportionately short legs, which may increase BMI without increasing body fat because of the relatively larger trunk compared with the legs. METHODS: A sample of 57 urban Maya schoolchildren, aged 7-9 years (31 boys), and 53 adult women underwent anthropometric assessments and bioelectrical impedance analysis. Multiple linear regression was performed to determine whether the ability of BMI to predict adiposity indicators is altered by stunting and sitting height ratio (SHR). The adiposity indicators were waist circumference, sum of skinfolds, upper arm muscle area, upper arm fat area, and arm fat index. RESULTS: BMI was the strongest predictor of all adiposity indicators and in most cases, explained more of the variance in adiposity of Maya children than Maya women. Abdominal adiposity was better predicted by BMI than peripheral adiposity in Maya women and Maya children. Stunting was significant in predicting adiposity in some models but never substantially changed the variance explained. SHR was never a significant predictor. CONCLUSIONS: The relationship between BMI and adiposity indicators is not changed by stunting status or body proportions in this short population of urban Maya children and women. BMI can be used as an indicator of adiposity for these children but not the women. It is recommended that BMI is used in conjunction with other estimates of body composition.