Validity of equations for estimating V[combining dot above]O2peak from the 20-m shuttle run test in adolescents aged 11-13 years

A comparison of the effects of two protocols of concurrent resistance and aerobic training on physical fitness in middle school students

Objective

This study aimed to compare the effects of two concurrent training (CT) protocols on the physical fitness of middle school students.

Method

A 12-week quasi-experimental pre-test/post-test study was conducted with 157 middle school students (age = 12.48 ± 0.34, n = 90 females) divided into three groups: CT group A (CT-0h) received combined resistance training (RT) and aerobic training (AT) in each physical education session, CT group B (CT-48h) received RT and AT across two separate physical education classes 48 h apart, and a control group (Con) received no training. Training occurred twice a week. Test indicators included cardiorespiratory fitness (CRF) measured by estimated VO2max and 20 m shuttle run (laps), as well as muscle strength assessed through long jump, vertical jump, and handgrip strength.

Results

The intervention groups exhibited significant increases in estimated VO2max and muscle strength compared to their baseline values (p < 0.05). Both CT-0h and CT-48h groups demonstrated significant improvements in 20 m shuttle run (laps) (mean difference: 8.88 laps, p < 0.01; mean difference: 4.81 laps, p < 0.01, respectively), standing long jump (mean difference: 6.20 cm, p < 0.01; mean difference: 3.68 cm, p < 0.01, respectively), vertical jump (mean difference: 4.95 cm, p < 0.01; mean difference: 4.04 cm, p < 0.01, respectively), and handgrip strength (mean difference: 11.17 kg, p < 0.01; mean difference: 6.99 kg, p < 0.01, respectively). CT-0h group exhibited significantly increased estimated VO2max (mean difference: 1.47 ml/kg/min, p < 0.01) compared to the CT-48h group.

Conclusion

Both CT programs effectively improved adolescents' physical fitness indicators. However, the program that integrated RT and AT within the same physical education class demonstrated superior enhancement in adolescents' CRF.

The Multistage 20-m Shuttle Run Test for Predicting VO2Peak in 6–9-Year-Old Children: A Comparison with VO2Peak Predictive Equations

Simple Summary

Cardiorespiratory fitness is one of the main components of physical fitness. For children, a simple test that can be used to assess cardiorespiratory fitness is the multistage 20-m shuttle run test (20mSRT). Research has often used a portable gas analyzer to measure cardiorespiratory fitness in clinical and scientific settings; however, this may not be practical due to the high cost of the device. Moreover, the use of such a device with children is almost impracticable in school environments. Thus, to avoid using such a device, one possibility is to use equations for predicting peak oxygen consumption, which is recognized as one of the best indicators of aerobic fitness. In the present study, 22 equations were used to determine which predictive equations had greater agreement with VO₂peak values measured by direct oximetry through performance of the 20mSRT. Furthermore, we verified if wearing and carrying a portable gas analyzer constrained the children’s performances. To accomplish these aims, 67 boys and 63 girls were included in the analysis. Our results showed that only six predictive equations correctly predicted the peak oxygen consumption. In addition, for girls, higher values of maximal speed, total laps, and total time were found when a portable gas analyzer was used. This information is helpful to strength and conditioning professionals and to schoolteachers if portable gas analyzers are unavailable or if the environment is not suitable for such assessments.

Abstract

This study aimed (i) to verify if using and carrying a portable gas analyzer (PGA) constrained the performance of school children on the multistage 20-m shuttle run test (20mSRT), (ii) to verify which peak oxygen consumption (VO₂peak) predictive equations have greater agreement with VO₂peak values measured by direct oximetry using the 20mSRT. The study participants were 130 children ((67 boys (age 7.76 ± 0.97 years) and 63 girls (age 7.59 ± 0.91 years)), who performed two randomized trials of the 20mSRT with and without a PGA. Twenty-two predictive equations predicted the VO₂peak values through the performance of the test with and without a PGA. Without a PGA, lower values of maximal speed (MS), total laps (TL), and total time (TT) were found for girls than for boys with a PGA. Only six equations were considered to correctly predict VO₂peak. In general, higher MS, TL, and TT values were found with the use of a PGA. The predicted VO₂peak values from the 20mSRT varied significantly among the published predictive equations. Therefore, we suggest that the six equations that presented satisfactory accuracy could be practically used to examine cardiorespiratory fitness in schools and in research with large populations when direct measurement of VO₂peak is not feasible.

Integrating High-Intensity Interval Training into a School Setting Improve Body Composition, Cardiorespiratory Fitness and Physical Activity in Children with Obesity: A Randomized Controlled Trial

The aim of this study was to examine the effects of school-based high-intensity interval training (HIIT) on cardiorespiratory fitness and visceral adipose tissue (VAT) in children with obesity. A total of 40 students (11.0 ± 0.6 years; 20 boys) were randomized into an intervention group (IG) and control group (CG). The IG group performed a 12-week HIIT intervention with three sessions per week. Each session included 18 min of training (three sets of eight bouts of 15 s run at 100% maximal aerobic speed (MAS) separated by eight bouts of 15 s recovery run at 50% MAS) in PE class; the CG group were instructed to continue their normal behaviors. All subjects had indices of body mass index (BMI), fat mass (FM), body fat percentage (%BF), fat free mass (FFM), VAT, and maximal oxygen uptake (VO2max) measured at baseline and post-intervention. The cooperation of students was high, and all 40 students were included in the final analysis. A significant group−time interaction was determined in body composition (p < 0.05), with a significant decrease in BM (−3.4 ± 1.4 kg, p = 0.001; η2 = 0.63), BMI (−1.7 ± 0.5, p = 0.001; η2 = 0.58), %BF (−3.3 ± 1.4, p = 0.001; η2 = 0.54), and FM (−3.2 ± 1.4 kg, p = 0.001; η2 = 0.69), and VAT (−22.4 ± 9.8 cm2; p = 0.001; η2 = 0.61) in the IG. Furthermore, VO2max exhibited a significant increase in the IG (4.5 ± 1.6 mL/kg/min, p = 0.001; η2 = 0.84) and CG groups (1.7 ± 1.1 mL/kg/min, p = 0.001; η2 = 0.44). Integrating regular school-based HIIT sessions is a suitable method to improve body composition, cardiorespiratory fitness, and physical activity in students with obesity. Trial Registration: ChiCTR2100048737.

Comparison of VO2peak from the Progressive Aerobic Cardiovascular Endurance Run (PACER) and treadmill in children

Background/Objectives

Methods

Results

Conclusions

The Cardiorespiratory fitness of children and adolescents in Tibet at altitudes over 3,500 meters

BACKGROUND

Cardiorespiratory fitness (CRF) is the core element of health-related physical fitness evaluation. High pressure and low oxygen in Tibet (over 3,500 m above sea level) may negatively impact the residents' CRF. The 20-m shuttle run test (20mSRT) is the most popular field-based assessment and estimate of CRF in children and adolescents worldwide. However, normative CRF data for the children and adolescents residing in China's plateau region are unavailable, which prevents comparability among those living at high-altitudes around the world.

PURPOSE

To measure the CRF of Chinese children and adolescents aged 9-18 years living in Tibet at altitudes exceeding 3,500 m, and to identify correlations between this metric and demographic characteristics (age, sex, and ethnicity). These data were then compared with those generated in the lowland (Shanghai, China) and various global regions.

METHODS

20mSRT performance (number of completed laps) and predicted peak oxygen consumption (VO2peak) were used as indicators of CRF. We measured the CRF of 1,717 healthy children and adolescents aged 9-18 years living in Tibet. The CRF data from school-age subjects in Shanghai (2,437 boys and 2,396 girls) and worldwide (1,142,026 students from 50 countries/regions in Africa, Asia, Europe, Latin America, North America, and Oceania) were collated from published papers.

RESULTS

The average CRF of the participants from Tibet was 39.8 mL/kg/min. The male subjects (n = 876; 41.1 ± 4.42 mL/kg/min) had a higher average CRF than their female counterparts (n = 841; 37.8 ± 5.40 mL/kg/min). CRF decreased with age in both sexes at statistical significance (F = 1249.9, p for trend 0.05). The indigenous Tibetans (n = 1289; 40.1 ± 3.71 mL/kg/min) had a significant higher average CRF than those of Han descent (n = 394; 38.9 ± 4.70 mL/kg/min) (p < 0.05).

CONCLUSIONS

Children and adolescents aged 7-18 years residing above 3,500 m in Tibet displayed lower CRF traits compared with their counterparts from the plains area and other high altitude places. CRF varied according to age, sex, and ethnic group. Given the importance of CRF in children and adolescents, effective intervention strategies should be implemented to improve CRF in children and adolescents on the plateau.

Does Maturity Status Affect the Relationship Between Anaerobic Speed Reserve and Multiple Sprint Sets Performance in Young Soccer Players?

Selmi, MA, Al-Haddabi, B, Yahmed, MH, and Sassi, RH. Does maturity status affect the relationship between anaerobic speed reserve and multiple sprints sets performance in young soccer players? J Strength Cond Res 34(12): 3600-3606, 2020-The purpose of this study is to examine the relationship between repeated-sprint sets (RSS) performance indices and anaerobic speed reserve (ASR) in young soccer players of different maturity status. One hundred seventy-nine young male soccer players (11.1-17.8 years) classified as pre- (n = 50), circum- (n = 60), or post- (n = 69) peak height velocity (PHV) performed multistage shuttle run test (MSRT) to measure maximal aerobic speed (MAS), 30-m sprint with 10-m splits to estimate maximal anaerobic speed (MAnS), and RSS test. Anaerobic speed reserve was calculated as the difference between MAS and MAnS. The RSS indices, MAS, MAnS, and ASR were significantly different in the 3 maturity groups (p < 0.001; effect size = 0.12-0.64). Correlations between RSS performance indices and ASR varied considerably depending on maturity status. Very large correlations between ASR and RSS indices expressed as sum sprint time (SST) and best sprint time (BST) were found for pre- and circum-PHV groups (r = -0.76, -0.79 and r = -0.82, -0.86, respectively). In the post-PHV group, ASR was moderately associated with both SST (r = -0.45) and BST (r = -0.46). To sum up, these results highlighted that the ASR is more related to factors of RSS performance in pre- and circum-PHV male soccer players compared with post-PHV ones. These findings could help coaches and strength and conditioning professionals to better understand how the relationship between ASR and RSS evolves across the maturity and may be considered, therefore, useful in youth soccer selection/training process.

Systolic blood pressure mediates the association between body mass index and inhibitory control in children

Here, we examine whether systolic blood pressure (SBP) mediates the relationship between body mass index (BMI) and inhibitory control in children. Twenty children with high blood pressure (HBP) were approximately matched with twenty children with low blood pressure (LBP) by fitness, BMI, somatic maturation, sex and age. Inhibitory control was measured by a cognitive Go/Nogo task, where number of commission errors during Nogo trials and reaction time during Go trials were used as performance. We compared performance between the two groups and conducted a mediation analysis using SBP as mediator of the relationship between BMI and commission errors. Results revealed that HBP children presented higher number of commission errors, compared to LBP children. Moreover, SBP mediated the relation between BMI and number of errors. Thus, early exposure to high levels of SBP can negatively impact inhibitory control and SBP acts as a mediator between BMI and inhibitory functioning in children.

Validation of equations to estimate the peak oxygen uptake in adolescents from 20 metres shuttle run test

This study aimed to develop new prediction models from directly determined peak of oxygen uptake (VO_2peak) in adolescents using 20-metre shuttle run test (20 m-SR) and to compare the new models with previously published equations. This study included 148 adolescents (43% girls), aged 13.37 ± 1.84 years old. Adolescents were randomly assigned to validation (n = 91) and cross-validation (n = 57) groups. VO_2peak was measured using a gas analyser in both maximal exercise tests in the laboratory as well as by 20 m-SR. The multiple linear regression method was applied to develop the models using BMI, BMI-z score and body fat percentage (%FM). The proposed models presented better predictive performance (R2 = 75.6% to 78.9%) and a lower absolute percentage error (%error = 10.51 to 11.78%) than the previously published equations (R2 = 38.8% to 69.1%; %error = 13.13% to 21.54%). The Model with BMI-z was the best fit equation in girls, and the model with BMI-z and %FM in boys. Therefore, it is recommended that the equations developed in the present study be used in future research and projects in the school environment to estimate VO_2peak in adolescents by the 20 m-SR test.

Developing and Validating a Step Test of Aerobic Fitness among Elementary School Children

Purpose: The tests to estimate aerobic fitness among children require substantial space and maximum effort, which is often difficult for children. We developed a simple submaximal step test (Step Test of Endurance for Pediatrics, or STEP) and assessed its reliability, validity, and ability to estimate aerobic fitness among elementary school children. Method: Children aged 5-10 years completed the STEP with a protocol consisting of 0.1-, 0.2-, and 0.3-metre (4, 8, and 12 in.) step heights. Participants underwent treadmill testing with open circuit spirometry to determine actual maximal oxygen consumption (V̇o_2max). Intra-class correlation coefficients (ICCs) assessed test-retest reliability of the STEP and its component tests. Multivariate linear regression assessed the associations between the STEP and V̇o_2max, adjusting for potential covariates such as age, sex, BMI, and comorbidity count. Results: The STEP showed excellent reliability (ICC ≥ 0.92; N = 170), irrespective of effort level during testing. Significant effort issues and collinearity among the independent variables led us to exclude children aged 5-6 years (n = 45) from the regression analysis. The final regression model for children aged 7-10 years with adequate effort (n = 111), as defined by a respiratory exchange ratio of 1.0 or more, showed that the STEP, sex, and BMI were significantly predictive of V̇o_2max (R ² = 0.51). Conclusions: This new, effort-independent step test can estimate the aerobic fitness of children aged 7-10 years. Regression equations to estimate V̇o_2max from the STEP were provided.

Allometric scaling of aerobic fitness outputs in school-aged pubertal girls

Background

This study aimed to determine the allometric exponents for concurrent size descriptors (stature, body mass and fat-free mass) and also to examine the contribution of chronological age and pubertal status combined with above mentioned size descriptors to explain inter-individual variability in the peak of oxygen uptake (VO_2peak) among girls during circumpubertal years.

Methods

The final sample included 51 girls (10.7–13.5 years). VO_2peak was derived from an incremental progressive maximal protocol using a motorized treadmill. Anthropometry included body mass, stature and skinfolds. Measurements were performed by a single trained observer. Sexual maturation was assessed as self-reported stage of pubic hair (PH) development. Static allometric models were explored as an alternative to physiological output per unit of size descriptors. Allometry also considered chronological age and sexual maturation as dummy variable (PH2 vs. PH3 and PH3 vs. PH4).

Results

Scaling coefficients for stature, body mass and fat-free mass were 1.463 (95%CI: 0.476 to 2.449), 0.516 (95%CI: 0.367 to 0.666) and 0.723 (95%CI: 0.494 to 0.951), respectively. The inclusion of sexual maturation increased explained variance for VO_2peak (55% for PH2 vs. PH3 and 47% for PH3 vs. PH4). Body mass was identified as the most prominent body size descriptor in the PH2 vs. PH3 while fat-free mass was the most relevant predictor combined with PH3 vs. PH4.

Conclusions

Body mass and fat-free mass seemed to establish a non-linear relationship with VO_2peak. Across puberty, inter-individual variability in VO_2peak is explained by sexual maturation combined with whole body during early puberty and by sexual maturation and fat-free mass during late puberty. Additional studies need to confirm ontogenetic allometric models during years of maximal growth.

PREDICTIVE EQUATIONS OF MAXIMUM OXYGEN CONSUMPTION BY SHUTTLE RUN TEST IN CHILDREN AND ADOLESCENTS: A SYSTEMATIC REVIEW

ABSTRACT Objective: To systematically review the literature as for the level of evidence of predictive equations of VO2peak through the 20-meter shuttle run test (20m-SRT) in children and adolescents. Data sources: Searches were conducted independently by two researchers, according to the procedures adopted by PRISMA, in the electronic databases MEDLINE via PubMed, ScienceDirect, Web of Science, LILACS and SciELO, for articles published until September 2017 in English and Portuguese. The inclusion criteria were: original studies, abstract available, using predictive equations of VO2peak through 20m-SRT, conducted with adolescents and/or children, non-athletes, and mentioning correlation analysis between predicted and measured VO2peak. The level of evidence of equations was based on the risk of bias of the studies using the following criteria: sample number, sample characteristics, and statistical analysis. Data synthesis: Eighteen studies were selected, in which fifteen equations were found and analyzed. The studies had been conducted with samples composed of subjects of both sexes, aged 8 to 19 years. Equations of Léger and Matsuzaka had their level of evidence classified as high, and estimation ranged between r=0.54-0.90 and r=0.65-0.90. Equations by Ruiz, Barnett and Matsuzaka had their level of evidence classified as moderate, and estimation ranged between r=0.75-0.96, r=0.66-0.84 and r=0.66-0.89, respectively. Conclusions: Matsuzaka’s equation presented satisfactory parameters for estimates of VO2peak in children and adolescents. Although not explored in equations, body adiposity and pubertal stage are significantly associated with cardiorespiratory fitness in children and adolescents.

VALIDITY OF FIELD TESTS TO ESTIMATE CARDIORESPIRATORY FITNESS IN CHILDREN AND ADOLESCENTS: A SYSTEMATIC REVIEW

Objective:

To systematically review the literature to verify the validity of field-tests to evaluate cardiorespiratory fitness (CRF) in children and adolescents.

Data sources:

The electronic search was conducted in the databases: Medline (PubMed), SPORTDiscus, Scopus, Web of Science, in addition to the Latin American databases LILACS and SciELO. The search comprised the period from the inception of each database until February 2015, in English and Portuguese. All stages of the process were performed in accordance with the PRISMA flow diagram.

Data synthesis:

After confirming the inclusion criteria, eligibility, and quality of the studies, 43 studies were analyzed in full; 38 obtained through the searches in the electronic databases, and 5 through private libraries, and references from other articles. Of the total studies, only 13 were considered high quality according to the adopted criteria. The most commonly investigated test in the literature was the 20-meter shuttle run (SR-20 m), accounting for 23 studies, followed by tests of distances between 550 meters and 1 mile, in 9 studies, timed tests of 6, 9, and 12 minutes, also 9 studies, and finally bench protocols and new test proposals represented in 7 studies.

Conclusions:

The SR-20-m test seems to be the most appropriate to evaluate the CRF of young people with the equation of Barnett, recommended to estimate VO₂ peak. As an alternative for evaluating CRF, the 1-mile test is indicated with the equation proposed by Cureton for estimating VO₂ peak.

Commentary on the Assessment and Interpretation of Pediatric Aerobic Fitness-The Year That Was 2017

Three papers, which between them contribute to the current debate on the assessment and interpretation of pediatric aerobic fitness, were selected for commentary. The first paper (Children. 2017; 4:6; doi: 10.3390/children4010006 ) highlights the merits of clinical exercise testing and advocates the advancement of pediatric exercise testing through a rationale founded on demonstrated prognostic value of data obtained. It notes the lack of well-accepted definitions of exercise outcome variables in children and promotes the case for data harmonization across laboratories. The second paper (J Appl Physiol. 2017; 122: 997-1002) argues persuasively that the acceptance of peak oxygen uptake (peak [Formula: see text]) at the termination of an exercise test to voluntary exhaustion as a surrogate for a "true" maximal value (ie, [Formula: see text]) is no longer tolerable. The authors present a compelling case for the adoption of a follow-up verification test to unambiguously validate the achievement of [Formula: see text]. The third paper (Br J Sports Med. 2017; 1-10, doi: 10.1136/bjsports-2017-097982 ) compiles large, previously published datasets to provide a review of temporal trends in 20-m shuttle run test scores. The authors assert that temporal trends in 20-m shuttle run test performance provide meaningful insight into trends in population health. The commentary stresses the importance of scientific rigor in pediatric exercise testing, emphasizes the use of precise definitions when describing health-related variables, and cautions against the misuse of exercise outcome measures in recommendations relating to or impacting on young people's health and well-being.

Independent and Combined Effects of Weight Status and Maturation on Aerobic Fitness in Adolescent School-Aged Males

Batista, MB, Valente-dos-Santos, J, Duarte, JP, Sousa-e-Silva, P, Coelho-e-Silva, MJ, Werneck, AO, Ohara, D, Cyrino, ES, and Ronque, ERV. Independent and combined effects of weight status and maturation on aerobic fitness in adolescent school-aged males. J Strength Cond Res 34(9): 2663-2671, 2020-This study aimed to examine the independent and combined effects of pubertal and weight status on concurrent measurements of peak oxygen (V[Combining Dot Above]O2peak) in school-aged adolescent males. The final sample included 49 boys (12.3 ± 0.8 years). V[Combining Dot Above]O2peak was derived from an incremental progressive maximal protocol using a motorized treadmill. In addition, maximal oxygen uptake was estimated from a 20-m shuttle run test. Static allometric models were obtained as an alternative to performance output per unit of size descriptors. Weight status had a significant effect on V[Combining Dot Above]O2peak using simple ratio standards per unit of body mass (BM) with adolescents classified as overweight and obese (OWOB) attaining lower values of V[Combining Dot Above]O2peak. A similar trend was noted for the allometric models adopting body mass (ml·kgBM·min), stature (L·m·min), and fat-free mass (FFM; ml·kgFFM·min). Findings also suggest the influence and interaction of pubertal and weight status on absolute values of V[Combining Dot Above]O2peak. Considering the data obtained, linear equations to estimate V[Combining Dot Above]O2peak from the 20-m shuttle run test should not be applied to boys who are OWOB because it will produce inaccurate assessments of cardiorespiratory fitness and penalize those who are heavier. Equations for V[Combining Dot Above]O2peak prediction need to be specific for pubertal status and preferably consider FFM as a body size descriptor.

[Body composition and physical fitness in Colombian high school students from Ibagué]

INTRODUCTION

Body composition and other components of physical fitness have proved to be important markers of health condition.

OBJECTIVE

To analyze body composition and physical fitness in Colombian students from public high schools of Ibagué, as well as to study differences between sexes and age groups, and establish correlations between some of the variables.

MATERIALS AND METHODS

The sample consisted of 1,253 students (601 males; 652 females), with an age range of 10-20 years. The ALPHA-Fitness test (extended version) was applied. Body Mass Index (BMI), waist circumference and fat percentage were assessed.

RESULTS

Differences between sexes were found in the variables studied, with greater BMI and fat percentage among females (20.6 kg/m2 vs. 19.4 kg/m2 and 26.1% vs. 16.8%, respectively); however, waist circumference was greater in males (69.6 cm vs. 67.9 cm), who also showed better fitness in the rest of the physical tests (p<0.05). In both sexes, age was associated to increases in BMI (p<0.05), and among females to fat percentage as well (p<0.05); among males it was the opposite, as in them, age was inversely associated to fat percentage (p<0.05). For the rest of the physical tests, age was positively associated to fitness both in men and women, except for maximal oxygen uptake (VO2 max). Correlations were found between some of the variables studied.

CONCLUSIONS

Adiposity was significantly greater in females than in males (p<0.05). Males showed better levels of aerobic, musculoskeletal and motor capacities.

Normative reference values for the 20 m shuttle-run test in a population-based sample of school-aged youth in Bogota, Colombia: the FUPRECOL study

OBJECTIVES

Our aim was to determine the normative reference values of cardiorespiratory fitness (CRF) and to establish the proportion of subjects with low CRF suggestive of future cardio-metabolic risk.

METHODS

A total of 7244 children and adolescents attending public schools in Bogota, Colombia (55.7% girls; age range of 9-17.9 years) participated in this study. We expressed CRF performance as the nearest stage (minute) completed and the estimated peak oxygen consumption (V˙O2peak ). Smoothed percentile curves were calculated. In addition, we present the prevalence of low CRF after applying a correction factor to account for the impact of Bogota's altitude (2625 m over sea level) on CRF assessment, and we calculated the number of participants who fell below health-related FITNESSGRAM cut-points for low CRF.

RESULTS

Shuttles and V˙O2peak were higher in boys than in girls in all age groups. In boys, there were higher levels of performance with increasing age, with most gains between the ages of 13 and 17. The proportion of subjects with a low CRF, suggestive of future cardio-metabolic risk (health risk FITNESSGRAM category) was 31.5% (28.2% for boys and 34.1% for girls; X2 P = .001). After applying a 1.11 altitude correction factor, the overall prevalence of low CRF was 11.5% (9.6% for boys and 13.1% for girls; X2 P = .001).

CONCLUSIONS

Our results provide sex- and age-specific normative reference standards for the 20 m shuttle-run test and estimated V˙O2peak values in a large, population-based sample of schoolchildren from a large Latin-American city at high altitude.

Cardiorespiratory fitness effect may be under-estimated in 'fat but fit' hypothesis studies

BACKGROUND

Both cardiorespiratory fitness and body fat have been independently related to metabolic syndrome in adolescents; however, the strength of these relationships seems to be dependent on the outcome composition.

AIM

To analyse the relationship between cardiorespiratory fitness and body fat combined with different indicators of metabolic risk in adolescents.

SUBJECTS AND METHODS

The sample was composed of 957 adolescents (58.7% girls). Cardiorespiratory fitness was obtained using the 20-metre shuttle run test and skinfold thickness was collected for body fat estimation. Metabolic risk score was calculated from waist circumference, systolic and diastolic blood pressure, glucose, HDL cholesterol and triglycerides measurements and an alternative outcome without the central obesity indicator was adopted. Chronological age and somatic maturity were used as covariates.

RESULTS

Higher metabolic risk was observed in the highest fat/lowest fit adolescents (p < .05), regardless of sex and outcome. In the regression models, for full metabolic risk score, body fat presented higher coefficients compared to cardiorespiratory fitness in both sexes (boys: 0.501 vs -0.097; girls: 0.485 vs -0.087); however, in the metabolic risk without waist circumference, the coefficients became closer (boys: 0.290 vs -0.146; girls: 0.265 vs -0.120), with a concomitant decrease in body fat and increase in cardiorespiratory fitness coefficients.

CONCLUSION

These findings suggest that body fat is strongly related to cardiovascular risk, but, when the outcome is calculated without the central obesity indicator, cardiorespiratory fitness becomes more related to metabolic risk.

Cardiorespiratory fitness is related to metabolic risk independent of physical activity in boys but not girls from Southern Brazil

OBJECTIVE

Our aim was to determine the relationship between cardiorespiratory fitness (CRF) and metabolic risk in adolescents from Southern Brazil.

METHODS

We performed a school-based cross-sectional study in 1,037 adolescents (436 boys) aged 10-16 years from Londrina, PR, Brazil. CRF was determined by 20-m shuttle run test. A continuous metabolic risk score was obtained from the mean of fasting glucose, triglycerides, high density lipoprotein, blood pressure, and waist circumference z-scores. Age, physical activity (Baecke questionnaire), body mass index (BMI; weight/stature(2) ), and somatic maturity (Mirwald method) were included as covariates in multiple linear regression analyses.

RESULTS

CRF was related to metabolic risk in boys (β = -0.02, P < 0.01) and girls (β = -0.01, P = 0.02) after adjusting for chronological age, BMI, and somatic maturity. However, when adjusted for physical activity, CRF failed to explain metabolic risk in girls (β = -0.01, P = 0.24).

CONCLUSION

We conclude that CRF is independently and inversely related to metabolic risk in boys, but physical activity either mediates or confounds the association between CRF and metabolic risk in girls. Am. J. Hum. Biol. 28:534-538, 2016. © 2016 Wiley Periodicals, Inc.

The Andersen aerobic fitness test: reliability and validity in 10-year-old children

Background

High aerobic fitness is consistently associated with a favorable metabolic risk profile in children. Direct measurement of peak oxygen consumption (VO_2peak) is often not feasible, thus indirect tests such as the Andersen test are required in many settings. The present study seeks to determine the reliability and validity of the Andersen test in 10-year-old children.

Methods

A total of 118 10-year-old children (67 boys and 51 girls) were recruited from one school and performed four VO_2peak tests over three weeks: three Andersen tests (indirect) and one continuous progressive treadmill test (direct). Of these, 104 children provided valid data on all Andersen tests and 103 children also provided valid data on the direct treadmill test. Reliability and validity were assessed using Bland Altman plots and linear regression analysis.

Results

Bias (mean change) and random error (limits of agreement) were 26.7±125.2 m for test 2 vs. test 1 (p<.001 for mean difference) and 3.9±88.8 m for test 3 vs. test 2 (p = .514 for mean difference). The equation to estimate VO_2peak suggested by Andersen et al. (2008) showed a poor fit in the present sample; thus, we suggest a new equation: VO_2peak = 23.262+0.050*Andersen distance –3.858*gender –0.376*body weight (R² = 0.61, standard error of the estimate = 5.69, p<.001, boys = 0, girls = 1).

Conclusions

The Andersen test provided reliable and valid data on a group level. However, a substantial degree of individual variability was found for estimates of VO_2peak. Researchers should be aware of the amount of noise in indirect tests that estimate aerobic fitness.