Health effects of children's summer holiday programs: a systematic review and meta-analysis.

BACKGROUND: Unfavourable changes occur in children's health behaviours and outcomes during the summer holidays. This systematic review aimed to determine the effectiveness of summer holiday programs in mitigating these changes. METHODS: Six databases (MEDLINE, JBI, PsychINFO, Embase, ERIC and Scopus) were systematically searched for experimental controlled studies that investigated programs of at least 5 days' duration conducted exclusively during the summer holiday period on school-aged children (5-18 years). Primary outcomes were moderate-vigorous physical activity and energy intake. Secondary outcomes were sedentary behavior, diet quality, adiposity, and cardiorespiratory fitness. Risk of Bias was assessed using the PEDro tool. Effect sizes were calculated using random-effects meta-analysis with narrative synthesis of effects by student or program characteristics. RESULTS: Ten studies (two randomised controlled trials, and eight non-randomised controlled trials) involving 1,446 participants were included. Summer programs had a significant moderate effect on reducing sedentary behaviour (g= -0.59, 95%CI= -1.16, -0.03) and significant small effects on improving moderate-to-vigorous physical activity (g = 0.35, 95%CI = 0.02, 0.67) and adiposity (g= -0.25, 95% CI = -0.39, -0.10). No significant change was detected for cardiorespiratory fitness (g = 0.43, 95%CI= -0.32, 1.17), energy intake (g= -0.06, 95% CI -2.33, 2.22), or diet quality (g = 0.20, 95%CI= -0.43, 0.83). Summer program effectiveness did not appear to differ by child sociodemographic or program characteristics. Concerns regarding bias and high heterogeneity impacted results. CONCLUSIONS: Summer programs show potential in promoting healthier movement behaviours in children and supporting healthy body weight during the summer months. Although evidence from the included studies has limitations, these programs produced small to moderate effect sizes and present promising health intervention opportunities for children. Future research with more rigorous study designs and comprehensive reporting is needed to confirm these findings and better understand the impact of summer programs on children's health. PROSPERO REGISTRATION: CRD42023409795.

Comparison of objectively measured and estimated cardiorespiratory fitness to predict all-cause and cardiovascular disease mortality in adults: A systematic review and meta-analysis of 42 studies representing 35 cohorts and 3.8 million observations.

BACKGROUND: Cardiorespiratory fitness (CRF) is a powerful health marker recommended by the American Heart Association as a clinical vital sign. Comparing the predictive validity of objectively measured CRF (the "gold standard") and estimated CRF is clinically relevant because estimated CRF is more feasible. Our objective was to meta-analyze cohort studies to compare the associations of objectively measured, exercise-estimated, and non-exercise-estimated CRF with all-cause and cardiovascular disease (CVD) mortality in adults. METHODS: Systematic searches were conducted in 9 databases (MEDLINE, SPORTDiscus, Embase, Scopus, PsycINFO, Web of Science, PubMed, CINAHL, and the Cochrane Library) up to April 11, 2024. We included full-text refereed cohort studies published in English that quantified the association (using risk estimates with 95% confidence intervals (95%CIs)) of objectively measured, exercise-estimated, and non-exercise-estimated CRF with all-cause and CVD mortality in adults. CRF was expressed as metabolic equivalents (METs) of task. Pooled relative risks (RR) for all-cause and CVD mortality per 1-MET (3.5 mL/kg/min) higher level of CRF were quantified using random-effects models. RESULTS: Forty-two studies representing 35 cohorts and 3,813,484 observations (81% male) (362,771 all-cause and 56,471 CVD deaths) were included. The pooled RRs for all-cause and CVD mortality per higher MET were 0.86 (95%CI: 0.83-0.88) and 0.84 (95%CI: 0.80-0.87), respectively. For both all-cause and CVD mortality, there were no statistically significant differences in RR per higher MET between objectively measured (RR range: 0.86-0.90) and maximal exercise-estimated (RR range: 0.85-0.86), submaximal exercise-estimated (RR range: 0.91-0.94), and non-exercise-estimated CRF (RR range: 0.81-0.85). CONCLUSION: Objectively measured and estimated CRF showed similar dose-response associations for all-cause and CVD mortality in adults. Estimated CRF could provide a practical and robust alternative to objectively measured CRF for assessing mortality risk across diverse populations. Our findings underscore the health-related benefits of higher CRF and advocate for its integration into clinical practice to enhance risk stratification.

Activity levels across the intensity spectrum in athletes: a systematic review protocol.

Physical activity (PA) promotes better cardiometabolic health, physical function, brain health and longevity. In contrast, prolonged sedentary behaviour (SB) is a risk factor for many chronic diseases and poor health. Limited research has evaluated or synthesised how competitive sports participation influences PA across the lifespan. Some evidence suggests, ironically, that former competitive athletes may be insufficiently active and current athletes may be highly sedentary away from sport. This study describes the protocol for a systematic review and meta-analysis on activity levels across the intensity spectrum in athletes, addressing the primary research question: is sports participation significantly associated with PA and/or SB among current and former competitive athletes? PubMed, Embase, Cochrane Database of Systematic Reviews, Web of Science and SPORTDiscus databases will be searched. Two reviewers will independently screen titles/abstracts and full texts of selected abstracts. Data will be extracted regarding the study population, sport played, PA measures and protocols, outcomes of interest and findings. Primary outcomes will include step counts, daily activity across the intensity spectrum (ie, sedentary, light, moderate and vigorous PA), metabolic equivalent of task and whole-day energy expenditure. Secondary outcomes will include additional accelerometry measures of PA, activity patterns and self-reported PA. The risk of bias will be assessed using the National Institutes of Health Study Quality Assessment Tools. Extracted data will be presented using narrative synthesis and tabular presentation. Meta-analyses will be conducted to determine outcomes with sufficient data.PROSPERO registration number: CRD42024469267.https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=469267.

Weakness Status is Differentially Associated with Time to Diabetes in Americans.

Background: The purpose of this study was to evaluate the associations of (1) individual absolute and body size normalized weakness cut-points, and (2) the collective weakness classifications on time to diabetes in Americans. Methods: We analyzed data from 9577 adults aged at least 50-years from the Health and Retirement Study. Diabetes diagnosis was self-reported. A handgrip dynamometer measured handgrip strength (HGS). Males with HGS <35.5 kg (absolute), <0.45 kg/kg (normalized to body weight), or <1.05 kg/kg/m2 (normalized to BMI) were categorized as weak. Females were classified as weak if their HGS was <20.0 kg, <0.337 kg/kg, or <0.79 kg/kg/m2. Compounding weakness included falling below 1, 2, or all 3 cut-points. Results: Persons below the body weight normalized weakness cut-points had a 1.29 (95% confidence interval (CI): 1.15-1.47) higher hazard for incident diabetes, while those below the BMI normalized cut-points had a 1.30 (CI: 1.13-1.51) higher hazard. The association between absolute weakness and incident diabetes was insignificant (hazard ratio: 1.06; CI: 0.91-1.24). Americans below 1, 2, or all 3 collective weakness categories had a 1.28 (CI: 1.10-1.50), 1.29 (CI: 1.08-1.52), and 1.33 (CI: 1.09-1.63) higher hazard for the incidence of diabetes, respectively. Conclusions: Our findings indicate that while absolute weakness, which is confounded by body size, was not associated with time to diabetes, adjusting for the influence of body size by normalizing HGS to body weight and BMI was significantly associated with time to diabetes. This suggests that muscle strength, not body size, may be driving such associations with time to diabetes.

A comparison of visual and direct assessments of lumbar spine posture.

BACKGROUND: Posture is assessed clinically and used to guide treatment of low back pain. Collectively, the relevance of posture and clinical postural assessments have come under scrutiny. This study aimed to determine (a) the intra-rater and inter-rater reliability of visual assessments of lumbar lordosis, and (b) the agreement between visual and direct postural assessments. METHODS: Ten physiotherapists visually assessed the lumbar lordosis from 3D scans of 50 asymptomatic participants, and 15 duplicates, using a grading scale of deviations (range: 0 = normal to 3 = severe). Lumbar lordosis angle was directly assessed using the Vitus Smart 3D whole body scanner. Cohen's Kappa was used to determine the intra-rater and inter-rater reliability of visual assessments, with polyserial correlation (ps) used to determine the agreement between visual and direct assessments. RESULTS: Overall, 93% and 83% of all intra-rater and inter-rater differences in visual assessments were within a single grade point, respectively. The intra-rater and inter-rater reliability of visual assessments was moderate (κ (95%CI): 0.56 (0.45, 0.67)) and slight (κ (95%CI): 0.13 (0.08, 0.19)), respectively. The agreement between visual and direct assessments was moderate (ps = -0.41, p = 0.04). CONCLUSION: Visual assessments of lumbar posture demonstrated moderate repeatability and agreement with quantitative assessments. While agreement between assessors was slight, 83% of the visual ratings were within a single grade point, suggesting greater coherence among clinicians than our statistics suggested. As with any clinical assessments involving uncertainty, postural assessment should not solely guide treatment.

Physical Fitness Surveillance and Monitoring Systems Inventory for Children and Adolescents: A Scoping Review with a Global Perspective.

Surveillance of health-related physical fitness can improve decision-making and intervention strategies promoting health for children and adolescents. However, no study has comprehensively analyzed surveillance/monitoring systems for physical fitness globally. This review sought to address this gap by identifying: (1) national-level surveillance/monitoring systems for physical fitness among children and adolescents globally, (2) the main barriers and challenges to implementing surveillance/monitoring systems, and (3) governmental actions related to existing surveillance/monitoring systems. We used a scoping review to search, obtain, group, summarize, and analyze available evidence. Our review involved three stages: (1) identification of surveillance systems through a systematic literature review, with complementary search of the grey literature (e.g., reference lists, Google Scholar, webpages, recommendations), (2) systematic consultation with relevant experts using a Delphi method to confirm/add systems and to gather and analyze information on the barriers and challenges to implementing systems, and (3) Web searches for public documents on government sites and surveillance/monitoring system pages, and direct internet searches to identify relevant governmental actions related to surveillance systems. A total of 15 fitness surveillance/monitoring systems met our inclusion criteria. Experts identified a lack of government support and funding, and the low priority of fitness on the public health agenda as the main barriers/challenges to implementation. Several governmental actions related to surveillance systems were identified, including policies, strategies, programs, and guidelines. We propose a Global Observatory of Physical Fitness to help address these issues.

Weakness Thresholds Are Differentially Linked to Cognitive Function by Obesity Status in Older Americans.

Background: Weakness can be operationalized with several thresholds, which in turn, could impact associations with cognitive impairment when considering obesity status. Objective: We examined the associations of absolute, normalized, and collective weakness thresholds on future cognitive impairment by obesity status in older adults. Methods: We performed a secondary data analysis on the 2006-2018 waves of the Health and Retirement Study. A spring-type dynamometer collected handgrip strength (HGS). Males were categorized weak if their HGS was <35.5-kg (absolute), <0.45-kg/kg (body mass normalized), or <1.05-kg/kg/m2 (body mass index (BMI) normalized), while females were defined as weak if their HGS was <20.0-kg, <0.337-kg/kg, or <0.79-kg/kg/m2. The modified Telephone Interview of Cognitive Status examined cognitive function. Persons scoring ≤10 had a cognitive impairment. Obesity was categorized as BMI ≥30 kg/m2. Results: We included 7,532 and 3,584 persons aged ≥65-years living without and with obesity, respectively. Those without obesity but beneath the absolute weakness threshold had 1.54 (95% confidence interval (CI): 1.24-1.91) greater odds for future cognitive impairment. Persons with obesity and beneath each threshold also had greater odds for future cognitive impairment: 1.89 (95% CI: 1.28-2.78) for absolute, 2.17 (95% CI: 1.02-4.62) for body mass normalized, and 1.75 (95% CI: 1.10-2.80) for BMI normalized. Older Americans without obesity but underneath all the weakness thresholds had 1.32 (95% CI: 1.00-1.74) greater odds for impairment in cognitive function, while persons with obesity had 2.76 (95% CI: 1.29-5.93) greater odds. Conclusions: There should be consideration for how body size and different weakness thresholds may influence future cognitive outcomes.

Cardiorespiratory fitness has declined among French children since 1999, although the decline appears to be getting smaller.

BACKGROUND: Cardiorespiratory fitness (CRF) is a strong marker of current and future health. The aim of this study was to assess the national temporal trends in CRF for French children and adolescents between 1999 and 2022. METHODS: CRF data were obtained from several cross-sectional studies on 15 420 (51.1% boys) French children and adolescents aged 9-16 years between 1999 and 2022. The 20-m shuttle run test (20mSRT) estimated CRF. Body mass index (BMI) was calculated from measured height and body mass, with BMI z-scores (BMIz) calculated using WHO growth curves. The 20mSRT results were corrected for protocol and converted to z-scores (20mSRTz) using international sex- and age-specific norms. With additional adjustment for BMIz, temporal trends in mean 20mSRT performance (20mSRTz) were estimated using linear regression, with the distance max (Dmax) method used to locate a breakpoint and linear segments fitted to points below and above the breakpoint. Trends in distributional characteristics were assessed visually and described as the ratio of the coefficients of variation (CVs). RESULTS: After adjustment for protocol, age, sex, and BMIz, a large decline in mean 20mSRT performance (trend per decade (95% CI): -1.42 SDs (-1.45, -1.39) or -18.4% (95% CI: -18.8, -18.0)) between 1999 and 2022 was found. Dmax located a breakpoint for the two-linear-segment model in year 2010. There was a large decline in mean 20mSRT performance pre-2010 (trend per decade (95% CI): -2.31 SDs (-2.39, -2.24)), which reduced 0.06-fold to a negligible decline post-2010 (trend per decade (95% CI): -0.15 SD (-0.20, -0.10)). We also found that the trend in mean 20mSRT performance was not uniform across the population distribution. Between 1999 and 2022, there was a small trend in distributional asymmetry, with slightly smaller declines experienced by the high performers (above the 75th percentile). CONCLUSIONS: Our data suggest a large decline in the 20mSRT performance of French children and adolescents since 1999. This declining trend seems to have diminished considerably since 2010. Such declines in CRF could translate into declines in health status. Although a slowing in the declining trend in CRF in recent years is encouraging, more data are needed to confirm these findings.

Tracking of serum lipid levels from childhood to adulthood: Systematic review and meta-analysis.

BACKGROUND AND AIMS: The utility of lipid screening in pediatric settings for preventing adult atherosclerotic cardiovascular diseases partly depends on the lifelong tracking of lipid levels. This systematic review aimed to quantify the tracking of lipid levels from childhood and adolescence to adulthood. METHODS: We systematically searched MEDLINE, Embase, Web of Science, and Google Scholar in March 2022. The protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO; ID: CRD42020208859). We included cohort studies that measured tracking of lipids from childhood or adolescence (<18 years) to adulthood (≥18) with correlation or tracking coefficients. We estimated pooled correlation and tracking coefficients using random-effects meta-analysis. Risk of bias was assessed with a review-specific tool. RESULTS: Thirty-three studies of 19 cohorts (11,020 participants) were included. The degree of tracking from childhood and adolescence to adulthood differed among lipids. Tracking was observed for low-density lipoprotein cholesterol (pooled r = 0.55-0.65), total cholesterol (pooled r = 0.51-0.65), high-density lipoprotein cholesterol (pooled r = 0.46-0.57), and triglycerides (pooled r = 0.32-0.40). Only one study included tracking of non-high-density lipoprotein cholesterol (r = 0.42-0.59). Substantial heterogeneity was observed. Study risk of bias was moderate, mostly due to insufficient reporting and singular measurements at baseline and follow-up. CONCLUSIONS: Early-life lipid measurements are important for predicting adult levels. However, further research is needed to understand the tracking of non-high-density lipoprotein cholesterol and the stability of risk classification over time, which may further inform pediatric lipid screening and assessment strategies.

Cardiorespiratory fitness is a strong and consistent predictor of morbidity and mortality among adults: an overview of meta-analyses representing over 20.9 million observations from 199 unique cohort studies.

OBJECTIVE: To examine and summarise evidence from meta-analyses of cohort studies that evaluated the predictive associations between baseline cardiorespiratory fitness (CRF) and health outcomes among adults. DESIGN: Overview of systematic reviews. DATA SOURCE: Five bibliographic databases were searched from January 2002 to March 2024. RESULTS: From the 9062 papers identified, we included 26 systematic reviews. We found eight meta-analyses that described five unique mortality outcomes among general populations. CRF had the largest risk reduction for all-cause mortality when comparing high versus low CRF (HR=0.47; 95% CI 0.39 to 0.56). A dose-response relationship for every 1-metabolic equivalent of task (MET) higher level of CRF was associated with a 11%-17% reduction in all-cause mortality (HR=0.89; 95% CI 0.86 to 0.92, and HR=0.83; 95% CI 0.78 to 0.88). For incident outcomes, nine meta-analyses described 12 unique outcomes. CRF was associated with the largest risk reduction in incident heart failure when comparing high versus low CRF (HR=0.31; 95% CI 0.19 to 0.49). A dose-response relationship for every 1-MET higher level of CRF was associated with a 18% reduction in heart failure (HR=0.82; 95% CI 0.79 to 0.84). Among those living with chronic conditions, nine meta-analyses described four unique outcomes in nine patient groups. CRF was associated with the largest risk reduction for cardiovascular mortality among those living with cardiovascular disease when comparing high versus low CRF (HR=0.27; 95% CI 0.16 to 0.48). The certainty of the evidence across all studies ranged from very low-to-moderate according to Grading of Recommendations, Assessment, Development and Evaluations. CONCLUSION: We found consistent evidence that high CRF is strongly associated with lower risk for a variety of mortality and incident chronic conditions in general and clinical populations.

Collective Weakness Is Associated With Time to Mortality in Americans.

ABSTRACT: McGrath, R, McGrath, BM, Jurivich, D, Knutson, P, Mastrud, M, Singh, B, and Tomkinson, GR. Collective weakness is associated with time to mortality in Americans. J Strength Cond Res 38(7): e398-e404, 2024-Using new weakness cutpoints individually may help estimate time to mortality, but their collective use could improve value. We sought to determine the associations of (a) each absolute and body size normalized cut point and (b) collective weakness on time to mortality in Americans. The analytic sample included 14,178 subjects aged ≥50 years from the 2006-2018 waves of the Health and Retirement Study. Date of death was confirmed from the National Death Index. Handgrip dynamometry measured handgrip strength (HGS). Men were categorized as weak if their HGS was <35.5 kg (absolute), <0.45 kg·kg -1 (body mass normalized), or <1.05 kg·kg -1 ·m -2 (body mass index [BMI] normalized). Women were classified as weak if their HGS was <20.0 kg, <0.337 kg·kg -1 , or <0.79 kg·kg -1 ·m -2 . Collective weakness categorized persons as below 1, 2, or all 3 cutpoints. Cox proportional hazard regression models were used for analyses. Subject values below each absolute and normalized cutpoint for the 3 weakness parameters had a higher hazard ratio for early all-cause mortality: 1.45 (95% confidence interval [CI]: 1.36-1.55) for absolute weakness, 1.39 (CI: 1.30-1.49) for BMI normalized weakness, and 1.33 (CI: 1.24-1.43) for body mass normalized weakness. Those below 1, 2, or all 3 weakness cut points had a 1.37 (CI: 1.26-1.50), 1.47 (CI: 1.35-1.61), and 1.69 (CI: 1.55-1.84) higher hazard for mortality, respectively. Weakness determined by a composite measure of absolute and body size adjusted strength capacity provides robust prediction of time to mortality, thus potentially informing sports medicine and health practitioner discussions about the importance of muscle strength during aging.

The Effect of Sedentary Behaviour on Cardiorespiratory Fitness: A Systematic Review and Meta-Analysis.

BACKGROUND: Cardiorespiratory fitness (CRF) is an important indicator of current and future health. While the impact of habitual physical activity on CRF is well established, the role of sedentary behaviour (SB) remains less understood. OBJECTIVE: We aimed to determine the effect of SB on CRF. METHODS: Searches were conducted in MEDLINE, Embase, PsycINFO, CINAHL and SPORTDiscus from inception to August 2022. Randomised controlled trials, quasi-experimental studies and cohort studies that assessed the relationship between SB and CRF were eligible. Narrative syntheses and meta-analyses summarised the evidence, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) certainty was based on evidence from randomised controlled trials. RESULTS: This review included 18 studies that focused on youth (four randomised controlled trials, three quasi-experimental studies, 11 cohort studies) and 24 on adult populations (15 randomised controlled trials, five quasi-experimental studies, four cohort studies). In youth and adults, evidence from randomised controlled trials suggests mixed effects of SB on CRF, but with the potential for interventions to improve CRF. Quasi-experimental and cohort studies also support similar conclusions. Certainty of evidence was very low for both age groups. A meta-analysis of adult randomised controlled trials found that interventions targeting reducing SB, or increasing physical activity and reducing SB, had a significant effect on post-peak oxygen consumption (mean difference = 3.16 mL.kg-1.min-1, 95% confidence interval: 1.76, 4.57). CONCLUSIONS: Evidence from randomised controlled trials indicates mixed associations between SB and CRF, with the potential for SB to influence CRF, as supported by meta-analytical findings. Further well-designed trials are warranted to confirm the relationship between SB and CRF, explore the effects of SB independent from higher intensity activity, and investigate the existence of such relationships in paediatric populations. CLINICAL TRIAL REGISTRATION: PROSPERO CRD42022356218.

Tracking of apolipoprotein B levels measured in childhood and adolescence: systematic review and meta-analysis.

To quantify the tracking of apolipoprotein B (apoB) levels from childhood and adolescence and compare the tracking of apoB with low-density lipoprotein (LDL) cholesterol, a systematic search of MEDLINE, Embase, Web of Science, and Google Scholar was performed in October 2023 (PROSPERO protocol: CRD42022298663). Cohort studies that measured tracking of apoB from childhood/adolescence (< 19 years) with a minimum follow-up of 1 year, using tracking estimates such as correlation coefficients or tracking coefficients, were eligible. Pooled correlations were estimated using random-effects meta-analysis. Risk of bias was assessed with a review-specific tool. Ten studies of eight unique cohorts involving 4677 participants met the inclusion criteria. Tracking of apoB was observed (pooled r = 0.63; 95% confidence interval [CI] = 0.53-0.71; I2 = 96%) with no significant sources of heterogeneity identified. Data from five cohorts with tracking data for both lipids showed the degree of tracking was similar for apoB (pooled r = 0.59; 95% CI = 0.55-0.63) and LDL cholesterol (pooled r = 0.58; 95% CI = 0.47-0.68). Study risk of bias was moderate, mostly due to attrition and insufficient reporting. CONCLUSION: ApoB levels track strongly from childhood, but do not surpass LDL cholesterol in this regard. While there is strong evidence that apoB is more effective at predicting ASCVD risk than LDL cholesterol in adults, there is currently insufficient evidence to support its increased utility in pediatric settings. This also applies to tracking data, where more comprehensive data are required. WHAT IS KNOWN: • Apolipoprotein B is a known cause of atherosclerotic cardiovascular disease. • Apolipoprotein B levels are not typically measured in pediatric settings, where low-density lipoprotein cholesterol remains the primary lipid screening measure. WHAT IS NEW: • This meta-analysis of 10 studies showed apolipoprotein B levels tracked strongly from childhood but did not exceed low-density lipoprotein cholesterol in this regard. • More comprehensive tracking data are needed to provide sufficient evidence for increased utility of apolipoprotein B in pediatric settings.

Temporal trends in the physical fitness of Hong Kong children aged 6-12 years between 2003-04 and 2015-16.

Low physical fitness in childhood is linked with poor health now and in later life. This study estimated temporal trends in physical fitness for Hong Kong children aged 6-12 years from 2003-04 to 2015-16. Objectively measured body size and physical fitness data for 27,513 children were obtained from four population-representative surveys of Hong Kong primary school students. Temporal trends in means were estimated by population-weighted linear regression. Trends in distributional characteristics were visually described. Overall, there was a small increase in mean height (effect size (ES) = 0.20 (95%CI: 0.13, 0.28)), with a negligible increase (ES < 0.2) in mean body mass. When adjusted for trends in age, gender, and body size, there was a small decline in sit-and-reach performance (ES = -0.43 (95%CI: -0.43, -0.42)), a small improvement in 9-min run/walk performance (9-to-12-year-olds, ES = 0.26 (95%CI: 0.26, 0.27)), with negligible declines in handgrip strength, 6-min run/walk (6-to 8-year-olds), and sit-ups performance. Temporal trends were not always uniform across the population distribution, with declines in run/walk, sit-ups, and sit-and-reach performance generally largest in children with low fitness. Increased national health promotion strategies that address culturally specific factors are encouraged to further improve the existing trends, especially for children with low fitness.

Changes in fitness and fatness in Australian schoolchildren during the summer holidays: fitness lost, fatness regained? A cohort study.

BACKGROUND: Emerging evidence suggests that children's fatness increases and fitness declines at a greater rate during the summer holiday period, compared with the school year. The aim of this study was to compare rates of change in fitness and fatness over the in-term and summer holiday periods among Australian schoolchildren. A secondary aim was to explore whether rates of change differed according to the child's sex, socio-economic status (SES), pubertal status and weight status. METHODS: Children (n = 381) initially in Grade 4 (age 9) were recruited for this 2-year longitudinal study. Fatness (% body fat, BMI z-score, waist-to-height ratio) and fitness (20-m shuttle run and standing broad jump) were measured at the start and end of two consecutive years. Rates of change were calculated for the two in-school periods (Grades 4 and 5) and for the summer holiday period. Rates of change in fatness and fitness between in-school and holiday periods were compared, and differences in rates of change according to sex, socio-economic status, and weight status were explored. RESULTS: During the holidays, percentage body fat increased at a greater rate (annualised rate of change [RoC]: +3.9 vs. Grade 4 and + 4.7 vs. Grade 5), and aerobic fitness declined at a greater rate (RoC - 4.7 vs. Grade 4 and - 4.4 vs. Grade 5), than during the in-school periods. There were no differences in rates of change for BMI z-score, waist-to-height ratio or standing broad jump. Body fatness increased faster in the holidays (relative to the in-school period) in children who are overweight and from low-SES families. Aerobic fitness declined more rapidly in the holidays in children who are overweight. CONCLUSION: This study highlights that during the summer holiday period, children experience greater increases in fatness and declines in fitness, with children who live with low-SES families and are overweight being more affected. The findings suggest the need for targeted interventions during this period to address these negative health trends. TRIAL REGISTRATION: Australia New Zealand Clinical Trials Registry, identifier ACTRN12618002008202. Retrospectively registered on 14 December 2018.

Examining the role of different weakness categories for mobility and future falls in older Americans.

BACKGROUND: Recently developed absolute and body size normalized handgrip strength (HGS) cut-points could be used individually and collectively to predict mobility problems and falls. AIMS: We examined the associations of (1) each absolute and normalized weakness cut-point, (2) collective weakness categories, and (3) changes in weakness status on future falls in older Americans. METHODS: The analytic sample included 11,675 participants from the 2006-2018 waves of the Health and Retirement Study. Falls were self-reported. Men were classified as weak if their HGS was < 35.5-kg (absolute), < 0.45 kg/kg (body mass normalized), or < 1.05 kg/kg/m2 (body mass index normalized). While, women were considered weak if their HGS was < 20.0-kg, < 0.337 kg/kg, or < 0.79 kg/kg/m2. Collective weakness categorized those below 1, 2, or all 3 cut-points. The collective weakness categories were also used to observe changes in weakness status over time. RESULTS: Older Americans below each absolute and normalized cut-point had greater odds for future falls: 1.23 (95% confidence interval (CI): 1.15-1.32) for absolute weakness, 1.20 (CI 1.11-1.29) for body mass index normalized weakness, and 1.26 (CI 1.17-1.34) for body mass normalized weakness. Persons below 1, 2, or all 3 weakness cut-points had 1.17 (CI 1.07-1.27), 1.29 (CI 1.18-1.40), and 1.36 (CI 1.24-1.48) greater odds for future falls, respectively. Those in some changing weakness categories had greater odds for future falls: 1.26 (CI 1.08-1.48) for persistent and 1.31 (CI 1.11-1.55) for progressive. DISCUSSION: Collectively using these weakness cut-points may improve their predictive value. CONCLUSION: We recommend HGS be evaluated in mobility and fall risk assessments.

Tracking handgrip strength asymmetry from childhood to mid-life.

AIM: Determine if asymmetric handgrip strength exists in childhood and adulthood and quantify the degree of tracking of handgrip strength asymmetry over time. METHODS: Participants from the Childhood Determinants of Adult Health Study had their right and left handgrip strength measured using handgrip dynamometry in childhood (1985: 9-15 y), young adulthood (2004-06: 26-36 y) and/or mid-adulthood (2014-19: 36-49 y). Handgrip strength asymmetry was calculated as: strongest handgrip strength/strongest handgrip strength on the other hand. Participants were categorised based on the degree of their asymmetry (0.0%-10.0%, 10.1%-20.0%, 20.1%-30.0%, >30.0%). Tracking was quantified using Spearman's correlations and log binomial regression. RESULTS: Handgrip strength asymmetry was present in childhood and adulthood (>30.0% asymmetry: childhood = 6%, young adulthood = 3%, mid-adulthood = 4%). Handgrip strength asymmetry did not track between childhood and young- (r = 0.06, 95% CI = -0.02, 0.12) and mid-adulthood (r = 0.01, 95% CI = -0.09, 0.10). Tracking was more apparent between young- and mid-adulthood (r = 0.16, 95% CI = 0.09, 0.22). Participants with >30.0% asymmetry were at greater risk to maintain this status between childhood and young- (RR = 3.53, 95% CI = 1.15, 10.87) and mid-adulthood (RR = 2.14, 95% CI = 0.45, 10.20). CONCLUSION: Although handgrip strength asymmetry tracked relatively poorly, asymmetric handgrip strength was apparent in children and adults. Handgrip strength asymmetry does not exclusively affect older adults and should be considered in protocols to better understand its role across the life course.

The Role of Different Weakness Cut-Points for Future Cognitive Impairment in Older Americans.

OBJECTIVES: New absolute and normalized handgrip strength (HGS) cut-points may not yield similar predictive value for cognitive performance. We sought to determine the associations of (1) each absolute and normalized weakness cut-point, and (2) compounding weakness on future cognitive impairment in older Americans. DESIGN: Longitudinal panel. SETTING AND PARTICIPANTS: The analytic sample included 11,116 participants aged ≥65 years from the 2006 to 2018 waves of the Health and Retirement Study. Participants from the Health and Retirement Study completed detailed interviews that included physical measures and core interviews. METHODS: The modified Telephone Interview of Cognitive Status assessed cognitive function and persons scoring <11 were classified as having a cognitive impairment. A handgrip dynamometer measured HGS. Men were considered weak if their HGS was <35.5 kg (absolute), <0.45 kg/kg (body mass normalized), or <1.05 kg (body mass index normalized), whereas women were classified as weak if their HGS was <20.0 kg, <0.337 kg/kg, or <0.79 kg. Compounding weakness included those below 1, 2, or all 3 cut-points. Generalized estimating equations quantified the associations. RESULTS: Persons considered weak under the absolute cut-point had 1.62 (95% CI 1.34-1.96) greater odds for future cognitive impairment, but no significant associations were observed for those classified as weak under the body mass [odds ratio (OR) 1.12, CI 0.91-1.36] and body mass index normalized (OR 1.17, CI 0.95-1.43) cut-points. Older Americans below all 3 weakness cut-points had 1.47 (CI 1.15-1.88) greater odds for future cognitive impairment, but no significant associations were found for persons classified as weak under 1 (OR 1.08, CI 0.83-1.42) or 2 (OR 1.19, CI 0.91-1.55) cut-points. CONCLUSIONS AND IMPLICATIONS: Our findings suggest that each weakness cut-point has differential prognostic value for future cognitive impairment, and aggregating weakness cut-points may improve their predictive utility. Consideration should be given to how weakness categories are uniquely linked to cognitive function.