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.

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.

Blood Pressure at Different Life Stages Over the Early Life Course and Intima-Media Thickness.

Importance: Although cardiovascular disease (CVD) begins in early life, the extent to which blood pressure (BP) at different life stages contributes to CVD is unclear. Objective: To determine the relative contribution of BP at different life stages across the early-life course from infancy to young adulthood with carotid intima-media thickness (IMT). Design, setting, and participants: The analyses were performed in 2022 using data gathered from July 1989 through January 2018 within the Special Turku Coronary Risk Factor Intervention Project, a randomized, infancy-onset cohort of 534 participants coupled with annual BP (from age 7 months to 20 years), biennial IMT measurements (from ages 13 to 19 years), who were followed up with again at age 26 years. Exposures: BP measured from infancy (aged 7 to 13 months), preschool (2 to 5 years), childhood (6 to 12 years), adolescence (13 to 17 years), and young adulthood (18 to 26 years). Main outcomes and measures: Primary outcomes were carotid IMT measured in young adulthood at age 26 years. Bayesian relevant life-course exposure models assessed the relative contribution of BP at each life stage. Results: Systolic BP at each life stage contributed to the association with young adulthood carotid IMT (infancy: relative weight, 25.3%; 95% credible interval [CrI], 3.6-45.8; preschool childhood: relative weight, 27.0%; 95% CrI, 3.3-57.1; childhood: relative weight, 18.0%; 95% CrI, 0.5-40.0; adolescence: relative weight, 13.5%; 95% CrI, 0.4-37.1; and young adulthood: relative weight, 16.2%; 95% CrI, 1.6-46.1). A 1-SD (at single life-stage) higher systolic BP accumulated across the life course was associated with a higher carotid IMT (0.02 mm; 95% CrI, 0.01-0.03). The findings for carotid IMT were replicated in the Cardiovascular Risk in Young Finns Study that assessed systolic BP from childhood and carotid IMT in adulthood (33 to 45 years). Conclusion and relevance: In this cohort study, a life-course approach indicated that accumulation of risk exposure to BP levels at all life stages contributed to adulthood carotid IMT. Of those, the contribution attributed to each observed life stage was approximately equal. These results support prevention efforts that achieve and maintain normal BP levels across the life course, starting in infancy.

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.

The Influence of Dietary Counseling Over 20 Years on Tracking of Non-High-Density Lipoprotein Cholesterol from Infancy to Young Adulthood.

This 26-year study found that non-high-density lipoprotein cholesterol (non-HDL-C) levels tracked from infancy to young adulthood suggesting early-life non-HDL-C could predict future levels. However, infancy-onset dietary counseling reduced the odds of maintaining at-risk non-HDL-C, highlighting the potential importance of early interventions in preventing cardiovascular risk associated with high pediatric non-HDL-C.

Tracking of Cardiorespiratory Fitness from Childhood to Mid-adulthood.

High cardiorespiratory fitness (CRF) in adulthood is important for survival from major chronic diseases and preserving good health. We examined how childhood CRF tracks, or persists, into adulthood. Among a cohort of 748 school children followed over 34 years, we found child CRF correlated with young- (r = 0.30) and mid-adulthood (r = 0.16) CRF.

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.

Prevalence and Trends of Handgrip Strength Asymmetry in the United States.

Background: Strength asymmetries are a type of muscle function impairment that is associated with several health conditions. However, the prevalence of these asymmetries among adults from the United States remains unknown. We sought to estimate the prevalence and trends of handgrip strength (HGS) asymmetry in American adults. Methods: The unweighted analytic sample included 23,056 persons aged at least 50-years with information on HGS for both hands from the 2006-2016 waves of the Health and Retirement Study. A handgrip dynamometer measured HGS, with the highest recorded values for each hand used to calculate asymmetry. Persons were categorized into the following asymmetry severity categories: (1) >10%, (2) >20.0%, and (3) >30.0%. Survey weights were used to generate nationally-representative asymmetry estimates. Results: Overall, there were no statistically significant trends in HGS asymmetry categories over time. The prevalence of HGS asymmetry in the 2014-2016 wave was 53.4% (CI: 52.2-54.4), 26.0% (CI: 25.0-26.9), and 11.7% (CI: 10.9-12.3) for asymmetry at >10%, >20%, and >30%, respectively. HGS asymmetry was generally higher in older Americans compared to middle-aged adults at each wave. In the 2014-2016 wave, >30% asymmetry prevalence was 13.7% (CI: 12.7-14.6) in females and 9.3% (CI: 8.4-10.2) in males. Some differences in asymmetry prevalence by race and ethnicity were observed. Conclusions: The prevalence of asymmetry was generally high, especially in women and older adults. Ongoing surveillance of strength asymmetry will help monitor trends in muscle dysfunction, guide screening for disablement, identify subpopulations at risk for asymmetry, and inform relevant interventions.

Tracking of Cardiorespiratory Fitness and Physical Activity from Youth to Young Adulthood: Findings from the Prospective Special Turku Coronary Risk Factor Intervention Project (STRIP).

Using data from the Special Turku Coronary Risk Factor Intervention Project, cardiorespiratory fitness (rank-order correlation coefficient = 0.60-0.62) tracked stronger than physical activity (rank-order correlation coefficient = 0.27-0.38) between youth (age = 17 years) and young adulthood (age = 26 years). Cardiorespiratory fitness could help identify individuals at risk of maintaining poor fitness levels or developing adverse health in adulthood.

Association Between Risk Factors in Childhood and Sex Differences in Prevalence of Carotid Artery Plaques and Intima-Media Thickness in Mid-Adulthood in the Childhood Determinants of Adult Health Study.

Background The origins of sex differences in cardiovascular diseases are not well understood. We examined the contribution of childhood risk factors to sex differences in adult carotid artery plaques and intima-media thickness (carotid IMT). Methods and Results Children in the 1985 Australian Schools Health and Fitness Survey were followed up when they were aged 36 to 49 years (2014-19, n=1085-1281). Log binomial and linear regression examined sex differences in adult carotid plaques (n=1089) or carotid IMT (n=1283). Childhood sociodemographic, psychosocial, and biomedical risk factors that might contribute to sex differences in carotid IMT/plaques were examined using purposeful model building with additional adjustment for equivalent adult risk factors in sensitivity analyses. Women less often had carotid plaques (10%) than men (17%). The sex difference in the prevalence of plaques (relative risk [RR] unadjusted 0.59 [95% CI, 0.43 to 0.80]) was reduced by adjustment for childhood school achievement and systolic blood pressure (RR adjusted 0.65 [95% CI, 0.47 to 0.90]). Additional adjustment for adult education and systolic blood pressure further reduced sex difference (RR adjusted 0.72 [95% CI, 0.49 to 1.06]). Women (mean±SD 0.61±0.07) had thinner carotid IMT than men (mean±SD 0.66±0.09). The sex difference in carotid IMT (ß unadjusted -0.051 [95% CI, -0.061 to -0.042]) reduced with adjustment for childhood waist circumference and systolic blood pressure (ß adjusted -0.047 [95% CI, -0.057 to -0.037]) and further reduced with adjustment for adult waist circumference and systolic blood pressure (ß adjusted -0.034 [95% CI, -0.048 to -0.019]). Conclusions Some childhood factors contributed to adult sex differences in plaques and carotid IMT. Prevention strategies across the life course are important to reduce adult sex differences in cardiovascular diseases.

Top 10 International Priorities for Physical Fitness Research and Surveillance Among Children and Adolescents: A Twin-Panel Delphi Study.

BACKGROUND: The measurement of physical fitness has a history that dates back nearly 200 years. Recently, there has been an increase in international research and surveillance on physical fitness creating a need for setting international priorities that could help guide future efforts. OBJECTIVE: This study aimed to produce a list of the top 10 international priorities for research and surveillance on physical fitness among children and adolescents. METHODS: Using a twin-panel Delphi method, two independent panels consisting of 46 international experts were identified (panel 1 = 28, panel 2 = 18). The panel participants were asked to list up to five priorities for research or surveillance (round 1), and then rated the items from their own panel on a 5-point Likert scale of importance (round 2). In round 3, experts were asked to rate the priorities identified by the other panel. RESULTS: There was strong between-panel agreement (panel 1: rs = 0.76, p < 0.01; panel 2: rs = 0.77, p < 0.01) in the priorities identified. The list of the final top 10 priorities included (i) "conduct longitudinal studies to assess changes in fitness and associations with health". This was followed by (ii) "use fitness surveillance to inform decision making", and (iii) "implement regular and consistent international/national fitness surveys using common measures". CONCLUSIONS: The priorities identified in this study provide guidance for future international collaborations and research efforts on the physical fitness of children and adolescents over the next decade and beyond.

Childhood Factors Associated with Muscular Strength Trajectories between Childhood and Mid-Adulthood.

PURPOSE: To promote greater muscular strength across the life course and, in turn, help improve long-term health outcomes, strategies aimed at increasing muscular strength are required. To inform these strategies, this study identified childhood factors associated with muscular strength trajectories. METHODS: Prospective longitudinal study of 1280 Childhood Determinants of Adult Health participants who had a range of potentially modifiable factors (e.g., anthropometric measures, physical activity) and health and risk motivation items (e.g., attitudes, beliefs, and intentions on health-related actions) measured in childhood and had their muscular strength assessed up to three times between childhood and midlife. Associations between childhood factors and three predetermined life course muscular strength trajectories (identified previously using group-base trajectory modeling as follows: above average and increasing, average, and below average and decreasing) were examined using log multinomial regression. RESULTS: Greater physical fitness, physical activity, fat-free mass, enjoyment of physical activity, physical education, and school sports, and positive attitudes regarding the importance of exercising, staying fit, and body image were associated with a lower likelihood of being in the below average and decreasing muscular strength trajectory (relative risk range, 0.45-0.98). Greater physical fitness, physical activity, and fat-free mass, and attending an independent school were associated with a higher likelihood of being in the above average and increasing muscular strength trajectory (relative risk range, 1.03-1.93). CONCLUSIONS: In addition to providing health benefits in the short term, physical activity, physical fitness, positive health attitudes, and healthy weight in childhood may lead to better muscular strength in the long term.

Relative Contribution of Blood Pressure in Childhood, Young- and Mid-Adulthood to Large Artery Stiffness in Mid-Adulthood.

Background Blood pressure associates with arterial stiffness, but the contribution of blood pressure at different life stages is unclear. We examined the relative contribution of childhood, young- and mid-adulthood blood pressure to mid-adulthood large artery stiffness. Methods and Results The sample comprised 1869 participants from the Cardiovascular Risk in Young Finns Study who had blood pressure measured in childhood (6-18 years), young-adulthood (21-30 years), and mid-adulthood (33-45 years). Markers of large artery stiffness were pulse wave velocity and carotid distensibility recorded in mid-adulthood. Bayesian relevant life course exposure models were used. For each 10-mm Hg higher cumulative systolic blood pressure across the life stages, pulse wave velocity was 0.56 m/s higher (95% credible interval: 0.49 to 0.63) and carotid distensibility was 0.13%/10 mm Hg lower (95% credible interval: -0.16 to -0.10). Of these total contributions, the highest contribution was attributed to mid-adulthood systolic blood pressure (relative weights: pulse wave velocity, childhood: 2.6%, young-adulthood: 5.4%, mid-adulthood: 92.0%; carotid distensibility, childhood: 5.6%; young-adulthood: 10.1%; mid-adulthood: 84.3%), with the greatest individual contribution coming from systolic blood pressure at the time point when pulse wave velocity and carotid distensibility were measured. The results were consistent for diastolic blood pressure, mean arterial pressure, and pulse pressure. Conclusions Although mid-adulthood blood pressure contributed most to mid-adulthood large artery stiffness, we observed small contributions from childhood and young-adulthood blood pressure. These findings suggest that the burden posed by arterial stiffness might be reduced by maintaining normal blood pressure levels at each life stage, with mid-adulthood a critical period for controlling blood pressure.

Longitudinal associations of childhood fitness and obesity profiles with midlife cognitive function: an Australian cohort study.

OBJECTIVES: Clusters of low fitness and high obesity in childhood are associated with poorer health outcomes in later life, however their relationship with cognition is unknown. Identifying such profiles may inform strategies to reduce risk of cognitive decline. This study examined whether specific profiles of childhood fitness and obesity were associated with midlife cognition. DESIGN: Prospective study. METHODS: In 1985, participants aged 7-15 years from the Australian Childhood Determinants of Adult Health study were assessed for fitness (cardiorespiratory, muscular power, muscular endurance) and anthropometry (waist-to-hip ratio). Participants were followed up between 2017 and 2019 (aged 39-50). Composites of psychomotor speed-attention, learning-working memory and global cognition were assessed using CogState computerised battery. Latent profile analysis was used to derive mutually exclusive profiles based on fitness and anthropometry. Linear regression analyses examined associations between childhood profile membership and midlife cognition adjusting for age, sex and education level. RESULTS: 1244 participants were included [age: 44.4 ±â€¯2.6 (mean ±â€¯SD) years, 53% female]. Compared to those with the highest levels of fitness and lowest waist-to-hip ratio, three different profiles characterised by combinations of poorer cardiorespiratory fitness, muscular endurance and power were associated with lower midlife psychomotor-attention [up to -1.09 (-1.92, -0.26) SD], and lower global cognition [up to -0.71 (-1.41, -0.01) SD]. No associations were detected with learning-working memory. CONCLUSIONS: Strategies that improve low fitness and decrease obesity levels in childhood could contribute to improvements in cognitive performance in midlife.

Childhood cardiorespiratory fitness and the early markers of kidney disease in middle age: A population-based cohort study.

OBJECTIVES: To investigate the relationship of childhood cardiorespiratory fitness with early markers of chronic kidney disease, glomerular hyperfiltration and albuminuria, in midlife. DESIGN: Prospective cohort study. METHODS: This study included 1371 participants aged 36-49 years who participated in the 1985 Australian Schools Health and Fitness Survey when they were 7-15 years of age. Childhood cardiorespiratory fitness was estimated by the time taken to complete a 1.6- km run. Blood and urine samples were collected at follow-up. Log-binomial regression was used to determine the associations of childhood cardiorespiratory fitness with glomerular hyperfiltration [estimated glomerular filtration rate (mL/min/1.73 m2) > 95th percentile standardized for age and sex] and albuminuria (urine albumin-to-creatinine ratio ≥ 2.5 mg/mmol in males or ≥3.5 mg/mmol in females) in midlife. RESULTS: Compared with women with high childhood cardiorespiratory fitness, those with lower childhood cardiorespiratory fitness had a higher risk of glomerular hyperfiltration in midlife after adjusting for childhood age, the duration of follow-up, and midlife smoking status [adjusted relative risk = 2.86, 95% confidence interval, 1.04-7.86 for individuals with moderate childhood cardiorespiratory fitness (P = 0.04), and adjusted relative risk = 3.38, 95% confidence interval, 1.13-10.14 for individuals with low childhood cardiorespiratory fitness (P = 0.03)]. Further adjustment for childhood and midlife body mass index resulted in a slightly attenuated and statistically non-significant association. No significant associations were found with glomerular hyperfiltration in males or albuminuria in either males or females. CONCLUSIONS: Low cardiorespiratory fitness in childhood may increase the risk of glomerular hyperfiltration in midlife in females, possibly via a path through adult cardiorespiratory fitness.

Muscular strength measured across the life-course and the metabolic syndrome.

BACKGROUND AND AIMS: Low muscular strength associates with the metabolic syndrome (MetS). However, how muscular strength measured at different life stages contribute to the development of MetS is unknown. This study compared the contribution of muscular strength measured in youth, young- and mid-adulthood with MetS in midlife. METHODS AND RESULTS: Prospective longitudinal study of 267 Childhood Determinants of Adult Health Study participants who between 1985 and 2019 had measures of muscular strength (dominant grip strength) at three life stages (youth = 9-15 years, young adulthood = 26-36 years, mid-adulthood = 36-49 years) and had their MetS status assessed in mid-adulthood. Bayesian relevant life-course exposure models quantified associations between muscular strength at each life stage with MetS and estimated the maximum accumulated effect of lifelong muscular strength. The contribution of muscular strength at each life stage with MetS was equal (youth = 38%, young adulthood = 28%, mid-adulthood = 34%). A one standard deviation increase in cumulative muscular strength was associated with 46% reduced odds of MetS. Of all MetS components, muscular strength was most strongly negatively associated with high waist circumference. CONCLUSION: A life-course approach demonstrated reduced odds of MetS in midlife was associated with cumulatively high muscular strength since youth. This supports efforts to promote physical fitness throughout life.

Health-Related Criterion-Referenced Cut-Points for Cardiorespiratory Fitness Among Youth: A Systematic Review.

BACKGROUND: Cardiorespiratory fitness (CRF), which reflects the overall aerobic capacity of the cardiovascular, respiratory, and muscular systems, is significantly related to health among youth. OBJECTIVE: The aim of this systematic review was to identify health-related criterion-referenced cut-points for CRF among youth aged 5-17 years. METHODS: A systematic search of two electronic databases (MEDLINE and SPORTDiscus) was conducted in September 2020. Only peer-reviewed studies that developed health-related criterion-referenced cut-points for CRF among youth were eligible provided they included (1) youth aged 5-17 years from the general population; (2) at least one quantitative assessment of CRF (e.g., peak oxygen uptake [[Formula: see text]O2peak]); (3) at least one quantitative assessment of health (e.g., cardiometabolic risk); (4) a criterion for health; and (5) a quantitative analysis (e.g., receiver operating characteristic [ROC] curve) of at least one health-related cut-point for CRF. A narrative synthesis was used to describe the results of the included studies. RESULTS: Collectively, 29 included studies developed health-related criterion-referenced cut-points for CRF among 193,311 youth from 23 countries. CRF cut-points, expressed as [Formula: see text]O2peak, estimated using the 20-m shuttle run test, demonstrated high discriminatory ability (median area under the curve [AUC] ≥ 0.71) for both cardiometabolic and obesity risk. Cut-points derived from maximal cycle-ergometer tests demonstrated moderate discriminatory ability (median AUC 0.64-0.70) for cardiometabolic risk, and low discriminatory ability for early subclinical atherosclerosis (median AUC 0.56-0.63). Cut-points for CRF using submaximal treadmill exercise testing demonstrated high discriminatory ability for cardiometabolic risk, but only moderate discriminatory ability for obesity risk. CRF cut-points estimated using submaximal step testing demonstrated high discriminatory ability for cardiometabolic risk and moderate discriminatory ability for high blood pressure, while those for the 9-min walk/run test demonstrated moderate-to-high discriminatory ability for obesity risk. Collectively, CRF cut-points, expressed as [Formula: see text]O2peak, demonstrated moderate-to-high discriminatory ability (median AUC ≥ 0.64) for cardiometabolic risk, obesity risk, and high blood pressure. CONCLUSIONS: Currently, there is too wide a range of health-related criterion-referenced cut-points for CRF among youth to suggest universal age- and sex-specific thresholds. To further inform the development of universal cut-points, there is a need for additional research, using standardized testing protocols and health-risk definitions, that examines health-related criterion-referenced cut-points for CRF that are age, sex, and culturally diverse. CLINICAL TRIALS REGISTRATION: PROSPERO registration number: CRD42020207458.

Health-Related Criterion-Referenced Cut-Points for Musculoskeletal Fitness Among Youth: A Systematic Review.

BACKGROUND: Musculoskeletal fitness is an excellent functional measure that is significantly related to health among youth. OBJECTIVE: Our objective was to identify health-related criterion-referenced cut-points for musculoskeletal fitness (MSF) among youth. METHODS: A systematic search of two electronic databases (MEDLINE and SPORTDiscus) was conducted in September 2020. Only peer-reviewed studies that developed health-related criterion-referenced cut-points for MSF among youth were eligible provided they included (1) youth aged 5-17 years from the general population, (2) at least one quantitative assessment of MSF (e.g., muscular strength), (3) at least one quantitative assessment of health (e.g., cardiometabolic risk), (4) a criterion for health, and (5) a quantitative analysis [e.g., receiver operating characteristic (ROC) curve] of at least one health-related cut-point for MSF. A narrative synthesis was used to describe the results of included studies. RESULTS: Collectively, 13 studies that developed health-related criterion-referenced cut-points for MSF among 14,476 youth from 15 countries were included. Muscular strength demonstrated high discriminatory ability [median area under the curve (AUC) ≥ 0.71] for cardiometabolic risk/metabolic syndrome, sarcopenic obesity risk and bone health, and moderate discriminatory ability (median AUC 0.64-0.70) for asthma. Muscular power also demonstrated high discriminatory ability for bone health but only moderate discriminatory ability for cardiometabolic risk/metabolic syndrome and low discriminatory ability (median AUC 0.56-0.63) for cognition/academic performance. Both muscular endurance and flexibility demonstrated low discriminatory ability for musculoskeletal pain. Health-related cut-points for MSF that demonstrated significant discriminatory ability were generally higher for boys than for girls (for muscular strength and power) and generally increased with age for muscular strength and power but remained stable for flexibility. CONCLUSIONS: Data remain insufficient to establish universal health-related cut-points for MSF among youth. Despite variations in the health-related discriminatory ability of different MSF tests, handgrip strength and standing broad jump emerged as the two tests with the highest discriminatory ability. More research, using standardized testing protocols and health-risk definitions, is required to better triangulate universal health-related cut-points for MSF among youth. PROSPERO REGISTRATION NUMBER: CRD42020207458.