Recommendations for Reducing Heterogeneity in Handgrip Strength Protocols.

Handgrip dynamometers are widely used to measure handgrip strength (HGS). HGS is a safe and easy to obtain measure of strength capacity, and a reliable assessment of muscle function. Although HGS provides robust prognostic value and utility, several protocol variants exist for HGS in clinical settings and translational research. This lack of methodological consistency could threaten the precision of HGS measurements and limit comparisons between the growing number of studies measuring HGS. Providing awareness of the protocol variants for HGS and making suggestions to reduce the implications of these variants will help to improve methodological consistency. Moreover, leveraging recent advancements in HGS equipment may enable us to use more sophisticated HGS dynamometer technologies to better assess muscle function. This Special Article will 1) highlight differences in HGS protocols and instrumentation, 2) provide recommendations to better specify HGS procedures and equipment, and 3) present future research directions for studies that measure HGS. We also provided a minimum reporting criteria framework to help future research studies avoid underreporting of HGS procedures.

Temporal trends in handgrip strength for older Japanese adults between 1998 and 2017.

OBJECTIVE: to estimate temporal trends in handgrip strength (HGS) for older Japanese adults between 1998 and 2017. DESIGN AND METHODS: adults aged 60-79 years were included. Annual nationally representative HGS data (n = 176,449) for the 19-year study period were obtained from the Japanese Ministry of Education, Culture, Sports, Science and Technology. Temporal trends in mean HGS were estimated by sample-weighted regression models relating the year of testing to mean HGS. National trends in absolute, percent and standardised HGS were estimated by a post-stratified population-weighting procedure. Temporal trends in variability were estimated as the ratio of coefficients of variation (CVs). RESULTS: collectively, there was a small improvement in mean HGS of 1.4 kg (95% confidence interval [CI]: 1.3-1.5), 4.5% (95%CI: 4.3-4.7) or 0.27 standard deviations (95%CI: 0.26-0.28) between 1998 and 2017. The rate of improvement progressively increased over time, with more recent values (post-2008) 1.5-fold larger than earlier values. Gender- and age-related temporal differences were negligible. Variability in HGS declined substantially over time (ratio of CVs [95%CI]: 0.88 [0.86-0.90]), with declines 1.9-fold larger in women compared to men and 1.7-fold larger in 70- to 79-year-olds compared to 60- to 69-year-olds. CONCLUSIONS: there has been a small, progressive improvement in mean HGS for older Japanese adults since 1998, which is suggestive of a corresponding improvement in strength capacity. The substantial decline in variability indicates that the improvement in mean HGS was not uniform across the population.

Trends in the prevalence of childhood overweight and obesity in Australia between 1985 and 2008.

BACKGROUND: Popular media, health experts and researchers talk about a paediatric 'obesity epidemic' with exponentially increasing rates of obesity and overweight. However, some recent reports suggest that prevalence may have plateaued. This study examined trends in the prevalence of Australian childhood overweight and obesity since 1985. Specifically, it aimed to determine whether there have been (a) overall increases in average body mass index (BMI), (b) differential patterns of change within age groups and (c) increases in BMI within each weight-status category. METHOD: Forty-one Australian studies of childhood weight status conducted between 1985 and 2008 were reviewed. The studies included data on 264 905 Australians aged 2-18 years, with raw data being available on 70 758 children (27%). Children were classified as overweight or obese based on BMI using the criteria of Cole et al. (BMJ, 2000). The prevalence estimates were adjusted for age and sex, and plotted against measurement year using Lowess plots and two-linear-segment models. Where raw data were available, BMI z-scores (UK 1990 standard) were plotted against measurement year for all children and children in various age groups. Lowess plots and two-linear-segment models were used to assess secular trends in BMI z-scores pre- and post-1996 within age, gender and weight-status categories. RESULTS: There has been a plateau, or only slight increase, in the percentage of boys and girls classified as overweight or obese, with almost no change over the last 10 years. In boys and girls, prevalence rates have settled around 21-25% for overweight and obesity together, and 5-6% for obesity alone. Similar trends were found for BMI z-scores. These patterns were fairly consistent across the age span. Within each weight-status category, average BMI has not increased. CONCLUSIONS: Although levels of Australian paediatric overweight remain high, the prevalence of overweight and obesity seems to have flattened and has not followed the anticipated exponential trajectory.

Secular trends in the aerobic fitness test performance and body mass index of Korean children and adolescents (1968-2000).

There is increasing evidence that the aerobic fitness performance of children is declining, at least in developed countries. To see if there was evidence of similar trends in a non-Western country, this study analysed data on 6-18-year-old Koreans tested between 1968 and 2000 using distance runs ranging from 600 to 1200 m. All existing data on the results of children's aerobic fitness tests in Korea were collated. In addition to six individual studies, very large datasets were available from the Korean Ministries of Education, and the Ministry of Culture and Tourism. Data on a total of 22,127,265 6-18-year-old children were available in the form of group means and standard deviations. Data were collated for each age x sex x test group, and performances were expressed as percentages of the fitted values for the year 1992 to standardise across tests, ages and sexes. All age x sex x test groups were then combined, and curves were fitted using weighted regression. A two-linear segment model best described the pattern of change (r = 0.83, p < 0.001). There was a relatively slow decline (0.26 % per year) in the aerobic performance of Korean children between 1968 and 1984. After 1984, however, there was a steep decline in performance, averaging 0.80 % per year. The rate of decline was greater in boys, younger children and children from outside the capital Seoul. Changes in running performance showed a similar pattern to changes in estimated body mass index. Compared to other countries, there has been a sharp decline in Korean children's performance on tests of aerobic fitness, which has been concurrent with increases in estimated body mass index.

Global changes in anaerobic fitness test performance of children and adolescents (1958-2003).

AIM: To quantify the global changes in anaerobic fitness (operationalized as power and speed test performance) of children and adolescents. METHODS: Following an extensive review of the literature, 32 studies examining secular changes in power and speed test performance of children and adolescents were analysed. Performance changes were calculated at the country x age x sex x test level using weighted least-squares regression, and were expressed as a percentage of the weighted mean value for all data points in the regression. Negative values indicated performance declines, and positive values indicated improvements. RESULTS: Changes in power (n=20 802 925) and speed (n=28 320 308) test performance were calculated for 6-19 year olds from 27 countries and five geographical regions, for the period 1958-2003. Overall, power and speed test performances improved at +0.03% and +0.04% per annum, respectively. Performance changes were remarkably similar for boys and girls, and children and adolescents, and somewhat similar for different geographical regions, and high and low income economies. The pattern of change was reasonably consistent over time. CONCLUSION: The relative stability in anaerobic fitness test performances in recent decades could be due to the negating effects of increases in fat mass and fat-free mass on anaerobic performance.

Secular trends in physical performance of Australian children. Evidence from the Talent Search program.

AIM: This study examined trends in aerobic fitness in 12-15-year-old South Australian schoolchildren in the years 1995-2000, based on data from the Australian Sports Commission's Talent Search program. METHODS: A total of 18,631 children were tested. The aerobic performance test used was the 20 m shuttle run test (20 mSRT). The 20 mSRT scores were expressed as completed laps, and converted to estimated VO(2)max values. RESULTS: There were significant declines (p=0.04-0.0001) across all age-gender slices, equivalent to 0.18 to 0.36 ml O(2) x kg(-1) x min(-1) x yr(-1), or about 0.4-0.8% of mean values per year. The rate of decline is consistent with several other Australian and overseas studies in the years 1980-2000, which have used a variety of aerobic tests across a wide range of age groups. In relation to children of similar age in 7 other countries, Australian children show poor to average aerobic fitness levels. CONCLUSION: It is possible that the decay in Australian children's aerobic fitness is in part due to reduced physical activity.

Physiological correlates of bilateral symmetry in humans.

Departures from perfect bilateral symmetry are thought to mirror an organism's ability to maintain developmental homeostasis. There is evidence showing that symmetry is negatively correlated with evolutionary and physical fitness. The purpose of this study was to determine the relationship between symmetry and health-related physiological characteristics in males and females. Forty-six male and female subjects participated in this study. Both facial and anthropometric traits were investigated for deviations from perfect bilateral symmetry. After measurements were made the subjects were tested on a range of physiological variables. There was no pattern of consistent significant correlations between fluctuating asymmetry and the physiological variables across all traits, and poor inter-correlations between the fluctuating asymmetries measured at different sites. The study failed to confirm the hypothesis that symmetric individuals were physiologically fitter when compared to their asymmetric counterparts.