Correlates of ideal cardiovascular health in European adolescents: The HELENA study

BACKGROUND AND AIMS

The ideal cardiovascular health (iCVH) construct consists of 4 health behaviors (smoking status, body mass index, physical activity and diet) and 3 health factors (total cholesterol, blood pressure and fasting glucose). A greater number of iCVH components in adolescence are related to better cardiovascular health, but little is known about the correlates of iCVH in adolescents. Thus, the aim of the study was to examine correlates of iCVH in European adolescents.

METHODS AND RESULTS

The study comprised 637 European adolescents with complete iCVH data. Participants were part of the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study, a cross-sectional, multicenter study conducted in 9 different European countries. Correlates investigated were sex and age, family affluence scale, maternal education, geographic location, sleep time, television viewing, duration of pregnancy, birth weight and breastfeeding. Younger adolescents, those whose mothers had medium/high education or those who watched television less than 2 h per day had a greater number of iCVH components compared to those who were older, had a mother with low education or watched television 2 h or more daily (P ≤ 0.01).

CONCLUSION

Since in our study older adolescents had worse iCVH than younger adolescents, early promotion of cardiovascular health may be important. Future studies may also investigate the usefulness of limiting television viewing to promote iCVH. Finally, since adolescents of mothers with low education had poorer iCVH, it may be of special interest to tailor public health promotion to adolescents from families with low socioeconomic status.

Differences in forearm strength, endurance, and hemodynamic kinetics between male boulderers and lead rock climbers

This study examined differences in the oxygenation kinetics and strength and endurance characteristics of boulderers and lead sport climbers. Using near infrared spectroscopy, 13-boulderers, 10-lead climbers, and 10-controls completed assessments of oxidative capacity index and muscle oxygen consumption (m⩒O₂) in the flexor digitorum profundus (FDP), and extensor digitorum communis (EDC). Additionally, forearm strength (maximal volitional contraction MVC), endurance (force-time integral FTI at 40% MVC), and forearm volume (FAV and ΔFAV) was assessed. MVC was significantly greater in boulderers compared to lead climbers (mean difference = 9.6, 95% CI 5.2-14 kg). FDP and EDC oxidative capacity indexes were significantly greater (p = .041 and .013, respectively) in lead climbers and boulderers compared to controls (mean difference = -1.166, 95% CI (-3.264 to 0.931 s) and mean difference = -1.120, 95% CI (-3.316 to 1.075 s), respectively) with no differences between climbing disciplines. Climbers had a significantly greater FTI compared to controls (mean difference = 2205, 95% CI= 1114-3296 and mean difference = 1716, 95% CI = 553-2880, respectively) but not between disciplines. There were no significant group differences in ΔFAV or m⩒O₂. The greater MVC in boulderers may be due to neural adaptation and not hypertrophy. A greater oxidative capacity index in both climbing groups suggests that irrespective of climbing discipline, trainers, coaches, and practitioners should consider forearm specific aerobic training to aid performance.

Muscular fitness, fatness and inflammatory biomarkers in adolescents

BACKGROUND

Muscular fitness, cardiorespiratory fitness (CRF) and fatness are mutually related with chronic inflammation.

PURPOSE

To examine the independent association of muscular fitness with inflammatory biomarkers in adolescents from nine European countries.

METHODS

A total of 639 adolescents (296 boys) aged from 12.5 to 17.5 year were included in this report. Data collection took place in 2006-2007 and analyses in 2012. A muscular fitness score was computed from handgrip strength and standing long jump. CRF was measured using the 20 m shuttle run test. Z-scores of C-reactive protein, complement factors C3 and C4, leptin and white blood cell counts were summed to create a cluster of inflammatory biomarkers. Sex, age, pubertal stage and centre were used as main confounders. Additional models were further adjusted for insulin resistance (HOMA-IR) and sum of four skinfolds.

RESULTS

Muscular fitness was negatively associated with single and clustered inflammatory biomarkers (standardized β from -0.399 to -0.100, all P-values < 0.05). Additional adjustments for CRF and HOMA-IR weakened the associations, but they still remained significant. The association was no longer significant when adjusting for skinfolds. Decreasing values of inflammatory score were observed across incremental levels of muscular fitness in both non-overweight and overweight adolescents (P ≤ 0.05).

CONCLUSIONS

Adolescents with higher levels of muscular fitness present a lower chronic inflammation, and this seems to be explained by lower levels of fatness. Yet, overweight and obese adolescents may exhibit a less adverse profile if they maintain appropriate levels of muscular fitness.

Body adiposity index and incident hypertension: the Aerobics Center Longitudinal Study

BACKGROUND AND AIM

The body adiposity index (BAI) has been recently proposed as a new method to estimate the percentage of body fat. The association between BAI and hypertension risk has not been investigated yet. The aim of our study was to evaluate the ability of BAI to predict hypertension in males and females compared with traditional body adiposity measures.

METHODS AND RESULTS

The present follow-up analysis comprised 10,309 individuals (2259 females) free of hypertension from the Aerobics Center Longitudinal Study, who completed a baseline examination between 1988 and 2003. Body adiposity measures included BAI, body mass index (BMI), waist circumference, hip circumference, percentage of body fat and waist to hip ratio (WHR). Incident hypertension was ascertained from responses to mail-back surveys between 1990 and 2004. During an average of 9.1 years of follow-up, 872 subjects (107 females) became hypertensive. Hazard ratios (HRs) and 95% confidence intervals (95% CI) showed that males in the highest categories of all body adiposity measures showed a higher incident risk of hypertension (HRs ranged from 1.37 to 2.09). Females showed a higher incident risk of hypertension only in the highest categories of BAI, BMI and WHR (HRs ranged from 1.84 to 3.36).

CONCLUSION

Our results suggest that in order to predict incident hypertension BAI could be considered as an alternative to traditional body adiposity measures.

Moderate-to-vigorous physical activity is associated with decreases in body mass index from ages 9 to 15 years

OBJECTIVE

The purpose of this study is to determine whether time spent in objectively measured physical activity is associated with change in body mass index (BMI) from ages 9 to 15.

DESIGN AND METHODS

The participants were enrolled in the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development (n = 938). At ages 9, 11, 12, and 15 the time spent in moderate-to-vigorous physical activity (MVPA) was objectively measured, and BMI was calculated (kg/m(2) ). Longitudinal quantile regression was used to analyze the data. The 10th, 25th, 50th, 75th, and 90th BMI percentiles were modeled as the dependent variables with age and MVPA (h/day) modeled as predictors. Adjustment was also made for gender, race, sleep, healthy eating score, maternal education, and sedentary behavior.

RESULTS

A negative association between MVPA and change in BMI was observed at the 90th BMI percentile (-3.57, 95% CI -5.15 to -1.99 kg/m(2) per hour of MVPA). The negative association between time spent in MVPA and change in BMI was progressively weaker toward the 10th BMI percentile (-0.27, 95% CI -0.62 to 0.07 kg/m(2) per hour of MVPA). The associations remained similar after adjusting for the covariates, and when the analyses were stratified by gender.

CONCLUSION

Time spent in MVPA was negatively associated with change in BMI from age 9 to 15. The association was strongest at the upper tail of the BMI distribution, and increasing time spent in MVPA could help reduce the prevalence of childhood obesity.

Criterion-related validity of field-based muscular fitness tests in youth

AIM

The purpose of the present study was to analyze the association between isokinetic strength and field-based muscular fitness tests in youth.

METHODS

One hundred twenty-six adolescents (14.4±1.7 y) participated in the study. Upper and lower body isokinetic strength were measured at preset angular velocities of 90 º/s and 60 º/s, respectively. Muscular fitness was also assessed by means of field-based tests: handgrip strength, bent and extended arm hang tests, standing long jump, squat jump, countermovement jump and Abalakov jump. Height, weight and skinfold thickness were used to estimate body composition.

RESULTS

All field-based tests were significantly associated with isokinetic peak torque and power (P<0.001 in all cases). Handgrip strength and standing long jump showed the highest associations with the isokinetic parameters (0.61≤r≤0.87; 0.39≤R2≤0.76). Weight-bearing field tests increased on average 20 % their association (R2) with isokinetic parameters when standardized by individual's body weight (test score × weight), while the average increase was 16 % when standardized by fat-free mass (test score × fat-free mass).

CONCLUSION

Handgrip strength and standing long jump tests seem to be the most valid field-based muscular fitness tests when compared to isokinetic strength. These tests can be useful to assess muscular fitness in young people when laboratory methods are not feasible.

Reliability of field-based fitness tests in youth

The objective of this systematic review was to study the reliability of the existing field-based fitness tests intended for use with children and adolescents. The medical electronic databases MEDLINE, SCOPUS and SPORTS DISCUS were screened for papers published from January 1990 to December 2009. Each study was classified as high, low or very low quality according to the description of the participants, the time interval between measurements, the description of the results and the appropriateness of statistics. 3 levels of evidence were constructed according to the number of studies and the consistency of the findings. 32 studies were finally included in the present review. The reliability of tests assessing cardiorespiratory fitness (9 studies), musculoskeletal fitness (12 studies), motor fitness (3 studies), and body composition (10 studies) was investigated. Although some fitness components warrant further investigation, this review provides an evidence-based proposal for most reliable field-based fitness tests for use with children and adolescents: 20-m shuttle run test to measure cardiorespiratory fitness; handgrip strength and standing broad jump tests to measure musculoskeletal fitness; 4×10 m shuttle run test for motor fitness; and height, weight, BMI, skinfolds, circumferences and percentage body fat estimated from skinfold thickness to measure body composition.

Extracurricular physical activity participation modifies the association between high TV watching and low bone mass

OBJECTIVES

To examine whether different sedentary behaviours are associated with the risk of low bone mineral content in adolescents, and if so, whether extracurricular physical-sporting activity influences this association.

MATERIALS AND METHODS

A total of 277 adolescents from Zaragoza (168 females and 109 males) aged 13.0-18.5 yr within frame work of the multicentre AVENA study participated in this study. Bone mineral content (BMC), lean mass, and fat mass were measured with DXA. Physical activity and sedentary independent variables: participation in extracurricular physical-sporting activity (PA), h/d of television watching, playing video/computer games during school days and on weekend days and doing homework/studying. They all were assessed by questionnaire. The main outcome was low BMC, as defined by BMC Z-score for age and sex < percentile 10. Logistic regression was used to test the interaction and association of PA and sedentary variables with low BMC, after controlling for confounders like height, maturational status or lean mass.

RESULTS

Among the sedentary variables studied, only television watching > or =3 h/d was associated with an increased risk for low BMC in males (OR, 95% CI: 7.01, 1.73 to 28.40), after controlling for sexual maturation. When PA was in the models, television watching was not any longer associated with low BMC, while PA was so (OR, 95% CI: 0.23, 0.09 to 0.55). Involvement in such activity reduced the risk of low bone mass by 76% (P<0.01) independently of body mass, height and fat mass, but not of the lean mass.

CONCLUSION

Watching television for 3 or more h/d seems to be associated with an increased risk for low BMC in male adolescents. However, this association is mediated by participation in PA, suggesting that negative consequences of excessive television watching on adolescent bone health could be counteracted by sport participation. Longitudinal data and randomized controlled trials will confirm or contrast our findings.

Physical fitness levels among European adolescents: the HELENA study

OBJECTIVE

To report sex- and age-specific physical fitness levels in European adolescents.

METHODS

A sample of 3428 adolescents (1845 girls) aged 12.5-17.49 years from 10 European cities in Austria, Belgium, France, Germany, Greece (an inland city and an island city), Hungary, Italy, Spain and Sweden was assessed in the Healthy Lifestyle in Europe by Nutrition in Adolescence study between 2006 and 2008. The authors assessed muscular fitness, speed/agility, flexibility and cardiorespiratory fitness using nine different fitness tests: handgrip, bent arm hang, standing long jump, Bosco jumps (squat jump, counter movement jump and Abalakov jump), 4×10-m shuttle run, back-saver sit and reach and 20-m shuttle run tests.

RESULTS

The authors derived sex- and age-specific normative values for physical fitness in the European adolescents using the LMS statistical method and expressed as tabulated percentiles from 10 to 100 and as smoothed centile curves (P₅, P₂₅, P₅₀, P₇₅ and P₉₅). The figures showed greater physical fitness in the boys, except for the flexibility test, and a trend towards increased physical fitness in the boys as their age increased, whereas the fitness levels in the girls were more stable across ages.

CONCLUSIONS

The normative values hereby provided will enable evaluation and correct interpretation of European adolescents' fitness status.

Associations of muscular and cardiorespiratory fitness with total and central body fat in adolescents: the HELENA study

OBJECTIVE

to examine the association of healthrelated physical fitness with total and central body fat in adolescents.

PARTICIPANTS/METHODS

the present cross-sectional study comprises 363 Spanish adolescents (186 female participants) aged 12.5-17.5 years. We assessed fitness by the 20-m shuttle run test (cardiorespiratory fitness); the handgrip strength, the standing broad jump and the Abalakov tests (muscular strength); and the 4 × 10-m shuttle run test (speed-agility). Total body fat was measured by dual energy x-ray absorptiometry (DXA), BodPod and sum of six skinfolds, and central body fat was measured by DXA at three regions (R1, R2 and R3) and waist circumference.

RESULTS

the Abalakov, the standing broad jump, the 4 × 10-m shuttle run and the 20-m shuttle run tests were negatively associated with all markers of total and central body fat in men and women after controlling for age, pubertal status and objectively assessed physical activity (p<0.01). Handgrip strength test was positively associated with waist circumference (p<0.01).

CONCLUSIONS

lower body muscular strength and cardiorespiratory fitness are negatively and consistently associated with total and central body fat in adolescents, whereas levels of upper body muscular strength were superior in adolescents with higher levels of central body fat.

Criterion-related validity of field-based fitness tests in youth: a systematic review

The objective of this systematic review was to comprehensively study the criterion-related validity of the existing field-based fitness tests used in children and adolescents. The studies were scored according to the number of subjects, description of the study population and statistical analysis. Each study was classified as high, low and very low quality. Three levels of evidence were constructed: strong evidence, when consistent findings were observed in three or more high quality studies; moderate evidence, when consistent findings were observed in two high quality studies; and limited evidence when consistency of findings and/or the number of studies did not achieve the criteria for moderate. The results of 73 studies (50 of high quality) addressing the criterion-related validity of field-based fitness tests in children and adolescents indicate the following: that there is strong evidence indicating that the 20 m shuttle run test is a valid test to estimate cardiorespiratory fitness, that the hand-grip strength test is a valid measure of musculoskeletal fitness, that skin fold thickness and body mass index are good estimates of body composition, and that waist circumference is a valid measure to estimate central body fat. Moderate evidence was found that the 1-mile run/walk test is a valid test to estimate cardiorespiratory fitness. A large number of other field-based fitness tests presented limited evidence, mainly due to a limited number of studies (one for each test). The results of the present systematic review should be interpreted with caution due to the substantial lack of consistency in reporting and designing the existing validity studies.