Secular change in muscular strength of indigenous rural youth 6–17 years in Oaxaca, southern Mexico: 1968–2000

Blood Lead Level and Handgrip Strength in Preadolescent Polish Schoolchildren

Environmental pollutions, particularly toxic elements such as lead, are among the most significant factors affecting the growth and functional development of children. The aim of this study was to evaluate the effect of blood lead levels on handgrip strength (HGS) in urban children resident in the Copper Basin of Lower Silesia, Poland, controlling for the effects of chronological age, body size and socioeconomic status. The study included 165 boys (9−11 years of age) and 79 girls (9−10 years of age) from Polkowice town. Anthropometric measurements involved height, body mass and grip strength of the left and right hands. Maternal education was a proxy for socioeconomic status. Based on the median value of blood lead level (3.10 µg/dL), the two groups-below and above/equal median value-were defined. Analysis of covariance revealed that age (all p < 0.001), sex (at least p < 0.01), BMI (all p < 0.001), and blood lead level (at least p < 0.05) had a significant effect on the three indicators of HGS (right hand, left hand, average), while the level of maternal education did not significantly affect HGS (p > 0.05). The results of this study indicate a potentially negative effect of elevated blood lead level on grip strength in preadolescent children, irrespective of sex.

A Systematic Analysis of Temporal Trends in the Handgrip Strength of 2,216,320 Children and Adolescents Between 1967 and 2017

OBJECTIVE

To estimate national and international temporal trends in handgrip strength for children and adolescents, and to examine relationships between trends in handgrip strength and trends in health-related and sociodemographic indicators.

METHODS

Data were obtained through a systematic search of studies reporting temporal trends in the handgrip strength for apparently healthy 9-17-year-olds, and by examining large national fitness datasets. Temporal trends at the country-sex-age level were estimated by sample-weighted regression models relating the year of testing to mean handgrip strength. International and national trends were estimated by a post-stratified population-weighting procedure. Pearson's correlations quantified relationships between national trends in handgrip strength and national trends in health-related/sociodemographic indicators.

RESULTS

2,216,320 children and adolescents from 13 high-, 5 upper-middle-, and 1 low-income countries/special administrative regions between 1967 and 2017 collectively showed a moderate improvement of 19.4% (95% CI 18.4-20.4) or 3.8% per decade (95% CI 3.6-4.0). The international rate of improvement progressively increased over time, with more recent values (post-2000) close to two times larger than those from the 1960s/1970s. Improvements were larger for children (9-12 years) compared to adolescents (13-17 years), and similar for boys and girls. Trends differed between countries, with relationships between national trends in handgrip strength and national trends in health-related/sociodemographic indicators negligible-to-weak and not statistically significant.

CONCLUSIONS

There has been a substantial improvement in absolute handgrip strength for children and adolescents since 1967. There is a need for improved international surveillance of handgrip strength, especially in low- and middle-income countries, to more confidently determine true international trends.

PROSPERO REGISTRATION NUMBER

CRD42013003657.

Four decades of socio-economic inequality and secular change in the physical growth of Guatemalans

Objective:

To investigate changes in socio-economic inequalities in growth in height, weight, BMI and grip strength in children born during 1955–1993 in Guatemala, a period of marked socio-economic-political change.

Design:

We modelled longitudinal data on height, weight, BMI and hand grip strength using Super-Imposition by Translation and Rotation (SITAR). Internal Z-scores summarising growth size, timing and intensity (peak growth velocity, e.g. cm/year) were created to investigate inequalities by socio-economic position (SEP; measured by school attended). Interactions of SEP with date of birth were investigated to capture secular changes in inequalities.

Setting:

Urban and peri-urban schools in the region of Guatemala City, Guatemala.

Participants:

Participants were 40 484 children and adolescents aged 3–19 years of Ladino and Maya ancestry (n_observations 157 067).

Results:

The difference in height (SITAR size) between lowest and highest SEP decreased from −2·0 (95 % CI −2·2, −1·9) sd to −1·4 (95 % CI −1·5, −1·3) sd in males, and from −2·0 (95 % CI −2·1, −1·9) sd to −1·2 (95 % CI −1·3, −1·2) sd in females over the study period. Inequalities also reduced for weight, BMI and grip strength, due to greater secular increases in lowest-SEP groups. The puberty period was earlier and shorter in higher-SEP individuals (earlier SITAR timing and higher SITAR intensity). All SEP groups showed increases in BMI intensity over time.

Conclusions:

Inequality narrowed between the 1960s and 1990s. The lowest-SEP groups were still >1 sd shorter than the highest. Risks remain for reduced human capital and poorer population health for urban Guatemalans.

Grip strength and body composition in Turkana pastoralist children and adolescents

OBJECTIVES

In an earlier study, age changes and sex differences in grip strength were documented for adult Turkana pastoralists of Kenya (Little and Johnson, 1986). The objective here is to characterize age changes and sex differences in grip strength of Turkana children and adolescents in the context of arm lean tissue composition, and in comparison with other African, African-American, and non-Western populations.

METHODS

Anthropometric measurements, derived body composition values, and grip strength measures (maximum voluntary contraction) were taken on a sample of 232 nomadic Turkana pastoralist children (94 boys and 138 girls) aged 3 to 21 years. Relationships were tested between grip strength (in Newtons) and mid-upper arm (brachium) lean tissue cross-sectional areas. Comparisons were made among several different ethnic groups.

RESULTS

Turkana children and adolescents had low arm muscle (derived lean tissue) and grip strength values when compared with U.S. NHANES percentile references. Girls' percentile rankings were greater than boys' percentile rankings for muscle and for grip strength. Both boys and girls were intermediate when compared with other non-Western populations and U.S. strength grip reference values. Correlations between grip strength and arm lean tissue areas were highly significant for both boys and girls.

CONCLUSIONS

The greater relative muscle size and grip strength values of late adolescent girls compared to boys is consistent with an earlier study of adults. The difference is likely to result from greater physical subsistence activity and greater access to food in girls than in boys. Several suggestions are given to explain why Turkana youths have relatively small muscle sizes.

Age as a moderator of the secular trend for grip strength in Canada and the United States

PURPOSE

To determine whether grip strength changed on average over recent decades at each of two age levels (children and adolescents versus adults) in Canada and the US.

METHODS

For each sex, weighted least squares regression analyses were performed on mean grip strength values as reported in studies conducted from the 1960s onwards.

RESULTS

Grip strength did not change significantly as a function of year tested in children and adolescents, whereas it declined as a negatively accelerated function of year tested in adults.

CONCLUSION

The results are contrary to what might be expected given that body weight has increased in both countries in recent decades and given that grip strength has been found to be positively correlated with body weight. It is suggested that there was a concurrent change in a factor that operated to counteract the effect of increased body weight on grip strength, a prime candidate being a decrease in levels of serum vitamin D. It is also suggested that the secular decline in adult grip strength can be explained by a factor that affects muscular function but which has a long latency period, a prime candidate here being obesity history.