Cardiorespiratory fitness and activity explains the obesity-deprivation relationship in children

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]O_2peak]); (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]O_2peak, 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]O_2peak, 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.

The dose-response association between V̇O2peak and self-reported physical activity in children

BACKGROUND

Previous research into the association between aerobic fitness and physical activity in children is equivocal. However, previous research has always assumed that such an association was linear. This study sought to characterize the dose-response association between physical activity and aerobic fitness and to assess whether this association is linear or curvilinear and varies by sex, age and weight status.

METHODS

Physical activity (assess using the Physical Activity Questionnaire), aerobic fitness (20 m shuttle-run), BMI, screen-time and socio-demographic data were collected at ages 12, 14 and 16 years in (n = 1422) volunteers from 9 English schools. Multilevel-regression modelling was used to analyse the longitudinal data.

RESULTS

The analysis identified a significant inverted "u-shaped" association between VO₂max and PAQ. This relationship remained having controlling for the influences of sex, age and weight status. Daily screen time >4 hours and deprivation were also associated with being less fit (P < 0.01).

CONCLUSIONS

This longitudinal study suggests that the dose-response relationship between PA and aerobic fitness in children is curvilinear. The health benefits of PA are greater in less active children and that sedentary and less active children should be encouraged to engage in PA rather than more active children to increase existing levels of PA.

Physical-Activity-Related Injuries and Risk Factors among Secondary School Students in Hong Kong

Increase in physical activity (PA) might elevate risks for physical-activity-related injuries (PARIs). This study aimed to investigate the incidence rate and risk factors for PARIs among secondary school students in Hong Kong. All eligible students from three secondary schools were invited to participate in the study from November to December 2014. Information on PARI occurrences in the past 12 months, PA participation, and sociodemographics was collected. Multivariate and hierarchical logistic regression models were performed to estimate the risk of potential factors for PARIs. In total, 1916 students in forms 1-6 (aged 14.3 ± 1.7 years) completed valid questionnaires, with an overall yearly PARI incidence rate of 32.1% (boys: 34.3%; girls: 29.3%). There were sex differences in the risk factors identified, except that family size was associated with PARIs for all participants. Longer duration and higher intensity of PA increased the risk for PARI occurrences in both sexes. In conclusion, PARIs were prevalent among secondary school students in Hong Kong, and different sexes had different PARI incidence rates and were influenced by different risk factors. There is an urgent call for effective sex-specific interventions to prevent PARIs in this population.

Effects of the Girls on the Move randomized trial on adiposity and aerobic performance (secondary outcomes) in low-income adolescent girls

BACKGROUND

Limited, mixed evidence exists regarding the effectiveness of physical activity interventions on adiposity and aerobic performance in adolescent underrepresented populations.

OBJECTIVE

To examine effects of Girls on the Move on body mass index z-scores (BMI-z), percent (%) body fat, and aerobic performance in fifth- to eighth-grade underrepresented girls.

METHODS

A group randomized trial, involving 12 intervention and 12 control schools in low-income areas, was conducted. Participants (n = 1519) were low-active girls. The 17-week intervention included (a) a physical activity club, (b) two motivational interviewing sessions, and (c) one Internet-based session. BMI-z was determined from measured height and weight; % body fat was assessed using bioelectric impedance. Aerobic performance was assessed using a shuttle run. Demographics, physical activity (accelerometer), and pubertal development were assessed. Linear mixed models, adjusting for baseline, were used to examine group differences in postintervention.

RESULTS

No significant between-group differences in BMI-z existed at postintervention, but % body fat increased less among intervention than control group girls (Mchange = 0.43% vs 0.73%). Aerobic performance decreased less in intervention vs control (Mchange = -0.39 vs -0.57).

CONCLUSIONS

Although the intervention positively impacted % body fat and aerobic performance in underrepresented girls, more research is necessary to determine optimal implementation for yielding greater effects.

A cross-sectional study on the deprivation and sex differences in health-related fitness measures in school children

This study aimed to investigate deprivation and sex differences in selected health-relatedfitness measures in 9-12-year-old children. Data were captured on 3,407 children (49.3% boys; aged 10.5 ± 0.6 years). Cardiorespiratory fitness(20 m multistage shuttle run test; 20 m MSRT), muscular strength (handgrip strength) and body mass index (BMI) were measured. Welsh Index of Multiple Deprivation (WIMD) scores were used to make quintile groups. A two-way Analysis of Variance examined differences in BMI z-score by sex and WIMD quintiles. Two-wayAnalysis of Covariances investigated the effect of sex and WIMD quintiles on grip strength and shuttles achieved in 20 m MSRT, adjusting for BMI z-score and maturation, repectively. Independent of sex, children in the middle quintile had a significantly higher mean BMI z-score (p = 0.029) than their least deprived counterparts. There was a significant increase in grip strength (p = 0.005) and20 m MSRT (boys p < 0.001; girls p = 0.028) between most and least deprived quintiles. Significant differences in 20 m MSRT score were more apparent with decreases in deprivation in boys.Overall, inequalities exist in health-related fitness by sex and deprivation. These results can be used to inform focused services to improve current and future health.

Physical Activity-Related Injury and Its Associated Factors among Middle School Students in Southern China

Physical activity (PA) promotion is beneficial to gain and maintain optimal health, but might increase risks for physical activity-related injury (PARI). This cross-sectional study aimed to investigate the incidence rate and identify risk factors of PARI among Chinese middle school students. Selected via the method of cluster random sampling, students graded 7⁻8 (junior) and 10⁻11 (senior) from five middle schools (aged from 10 to 18 years old) in Shantou were invited to participate in the survey. Information on socio-demography, PA involvement, sleep duration, individual safety awareness and exercise behavior, and PARI experiences in the past 12 month was collected. Multivariate logistic regression model was performed to estimate the risk factors of PARI. A total of 3082 participants completed the valid questionnaires, with an overall incidence rate of 25.1%. Boys, junior school students, sports team members, and those with lower safety awareness, living with single parent, and without any chronic conditions were at higher risks for PARI. Moreover, exercising on wet floor or with illness frequently would also be more likely to experience injury, especially those with at least 120 min per day. In conclusion, PARI was prevalent among middle school students in southern China. The above data provide insights that were focused and effective actions should be taken to prevent school-aged adolescents from PARI and maximize the benefits of PA.