A Systematic Analysis Of Temporal Trends In The Sit-Ups Performance Of 9,939,289 Children And Adolescents Between 1964 And 2017 Representing 31 Countries

Objective: To estimate national and international temporal trends in the sit-ups performance of children and adolescents, and to examine relationships between trends in sit-ups performance and trends in health-related and sociodemographic indicators. Methods: Data were obtained in three ways: (a) through a systematic electronic database search of studies reporting on temporal trends in the handgrip strength of apparently healthy 9–17 year-olds, (b) by pearling reference lists, topical systematic reviews and personal libraries, and (c) by examining large country-level fitness datasets suitable to temporal trends analysis. Sample-weighted temporal trends (expressed as percent and standardized trends) were estimated at the country-sex-age level using best-fitting regression models relating the year of testing to mean sit-ups performance. International and national trends were estimated by post-stratified population-weighted mean changes standardized to the year 2000. Pearson’s correlations were used to quantify relationships between linear trends in sit-ups performance and linear trends in health-related and sociodemographic indicators. Results: Trend data from 27 studies/datasets representing 9,939,289 children and adolescents representing 31 countries (25 high-, 5 upper-middle-, and 1 low-income countries) between 1964 and 2017 collectively showed a large improvement in mean sit- ups performance of 38.4% (95%CI: 36.8 to 40.0) or 7.1% per decade (95%CI: 6.8 to 7.4). Large international improvements were experienced by all age and sex groups, with the rate of improvement slowing from 1964 to 2000, stabilizing near zero until 2010, before declining thereafter. Trends differed in magnitude and direction between countries, with most experiencing improvements. Trends in vigorous physical activity levels were a strong positive correlate of trends in sit-ups performance. Conclusions: There has been a large international improvement in children’s sit-ups performance since 1967, which has progressively diminished in magnitude over time. Sit- ups data are needed from children in low-income and middle-income countries in order to better monitor national and international trends in muscular fitness

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 trends in handgrip strength and 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 to 20.4) or 3.8% per decade (95%CI: 3.6 to 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 trends in handgrip strength and 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