[Lipid and metabolic profiles in adolescents are affected more by physical fitness than physical activity (AVENA study)]

Cardiorespiratory and Muscular Fitness in Children and Adolescents with Obesity

PURPOSE OF REVIEW

Examine the current state of literature related to the impact of obesity in children and adolescents on health-related physical fitness and the resultant cardiometabolic disease risk.

RECENT FINDINGS

Cardiorespiratory fitness of children and adolescents has declined over the past few decades which corresponds with an increase in obesity rates. Children with obesity are more likely to have low cardiorespiratory fitness which is associated with higher cardiometabolic disease risk and poorer mental health. The impact of obesity on muscular fitness in children and adolescents is more difficult to ascertain, but in general measures of physical function are lower in children with obesity which has also been associated with higher cardiometabolic disease risk. Components of health-related physical fitness are trending negatively in children and adolescents and appear to be related to the increase in prevalence of obesity. The resultant cardiometabolic disease risk has also risen which suggests a greater disease burden in the future. These disparaging findings highlight the need for aggressive interventions to improve physical fitness in children and adolescents.

Association of daily steps on lipid and glycaemic profiles in children: The mediator role of cardiorespiratory fitness

AIM

To analyse, in schoolchildren, the relationship between daily steps with metabolic parameters; and to examine whether this association is mediated by cardiorespiratory-fitness (CRF).

METHODS

A cross-sectional analysis of baseline data from a feasibility trial was performed in children from two primary schools in Cuenca, Spain. Daily steps were measured using the Xiaomi MI Band 3. Lipid and glycaemic profiles were analysed from blood samples. CRF was assessed using the 20-m shuttle run test. ANCOVA models were used to test the mean differences by daily steps quartiles. Mediation analyses were conducted to examine whether CRF mediates the association between daily steps and lipid and glycaemic parameters.

RESULTS

A total of 159 schoolchildren (aged 9-12 years, 53% female) were included in the analysis. Schoolchildren in the highest daily steps quartiles (>10 000 steps) showed significantly lower triglycerides and insulin levels (p = 0.004 and 0.002, respectively). This association did not remain after controlling for CRF. In mediation analyses, a significant indirect effect was observed through CRF in the relationship between daily steps with triglycerides and insulin.

CONCLUSION

Children who daily accumulate more than 10 000 steps have better lipid and metabolic profile, and CRF mediated their relationship in schoolchildren.

[Risk factor control, lifestyle intervention, and prescribed medication in a cohort of patients with ischemic heart disease]

OBJECTIVE

The aim of this study was to analyze the recommended prevention measures in our health area for patients discharged after a myocardial infarction.

METHODS

This was a retrospective descriptive study that selected patients with acute coronary syndrome in our health area in the previous calendar year. Control of the risk factors observed at the time of the coronary event and at 1 year and medication prescribed 1 year after the episode were studied. Variables including age, sex, control of dyslipidemia, hypertension or diabetes mellitus, adherence to treatment and lifestyle habits were analyzed.

RESULTS

Risk factor control was insufficient and sometimes even unassessed at the time of infarction. Although a slight improvement was perceived, control remained insufficient 1 year later. Moreover, patients, particularly women, were undertreated: one fifth (20%) more men were receiving appropriate treatment than women year after the myocardial event.

CONCLUSIONS

An additional effort must be made compared to what is currently being done, both by specialists in Hospital Care and Primary Care, to carry out good control of risk factors, meaning the control of certain diseases such as diabetes, high blood pressure or dyslipidemia, as well as habits or lifestyles that increase the probability of suffering a cardiovascular event. Furthermore, it is important to avoid these cardiovascular diseases and their relapse to reinforce adherence to the prescribed treatments.

Analysis of Adolescent Physical Activity Levels and Their Relationship with Body Image and Nutritional Habits

The main objective of this research article was to make a cluster analysis in Compulsory Secondary Education students with regard to their physical activity levels, their relationship with nutritional habits and body perception. In this study, a total of 1089 students participated, to whom a battery of tests was given in order to assess three aspects: levels of physical activity, food consumption habits and perception of body image. The main results indicated that the adolescent sample presented high levels of physical activity in comparison with other studies. In addition, a profile analysis was carried out, showing that there were no differences in physical activity, in nutritional habits or in body-image index. Taking into account gender, women who practice light physical activity had better nutritional habits. On the other hand, boys dominated in the group of moderate-to-high physical activity, while the girls were mainly included in the profile of low physical activity. Finally, body-image index was greater in men than women. It was concluded that is necessary to promote the importance of adequate nutritional habits in addition to physical activity, and it is necessary to promote body image, particularly among adolescent girls, given their low values of physical activity and worse body-image perception in relation to boys.

Muscular Fitness and Cardiometabolic Variables in Children and Adolescents: A Systematic Review

BACKGROUND

The importance of muscular fitness (MF) in the performance of activities of daily living is unequivocal. Additionally, emerging evidence has shown MF can reduce cardiometabolic risk in children and adolescents.

OBJECTIVES

The purpose of this study was to examine and summarize the evidence regarding the relationship between MF phenotypes (i.e., maximum muscular strength/power, muscular endurance, and maximum muscular strength/power/endurance) and cardiometabolic variables (obesity, blood pressure, lipids, glucose homeostasis, inflammatory markers, and clustered cardiometabolic variables) in children and adolescents.

DESIGN

This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and was registered with PROSPERO, number CRD42020179273.

DATA SOURCES

A systematic review was performed on five databases (PubMed, EMBASE, SciELO, Scopus, and Web of Knowledge) from database inception to May 2020, with complementary searches in reference lists.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Eligibility criteria included (1) a study sample of youth aged ≤ 19 years, (2) an assessment of MF with individual or clustered cardiometabolic variables derived from adjusted models (regardless of test/measurement adopted or direction of reported association), and (3) a report of the association between both, using observational studies. Only original articles published in peer-reviewed journals in English, Portuguese, and Spanish languages were considered. The quality of the included studies was assessed by using the National Heart, Lung, and Blood Institute checklist. The percentage of results reporting a statistically significant inverse association between each MF phenotype and cardiometabolic variables was calculated.

RESULTS

Of the 23,686 articles initially identified, 96 were included (77 cross-sectional and 19 longitudinal), with data from children and adolescents from 35 countries. The score for the quality of evidence ranged from 0.33 to 0.92 (1.00 maximum). MF assessed by maximum muscular strength/power was inversely associated with lower obesity (64/113 total results (56.6%)) and reduction in clustered cardiometabolic risk (28/48 total results (58.3%)). When assessed by muscular endurance, an inverse association with obesity (30/44 total results (68.1%)) and cardiometabolic risk (5/8 total results (62.5%)) was identified. Most of the results for the relationship between MF phenotypes with blood pressure, lipids, glucose homeostasis, and inflammatory markers indicated a paucity of evidence for these interrelationships (percentage of results below 50.0%).

CONCLUSION

MF assessed by maximum muscular strength/power or muscular endurance is potentially associated with lower obesity and lower risk related to clustered cardiometabolic variables in children and adolescents. There is limited support for an inverse association between MF with blood pressure, lipids, glucose homeostasis biomarkers, and inflammatory markers in children and adolescents.

Association between Physical Literacy and Self-Perceived Fitness Level in Children and Adolescents

Simple Summary

Alarming data on physical inactivity and sedentary lifestyles in children and young people are increasing. The level of physical fitness is considered a predictor of morbidity and comorbidities resulting from physical inactivity. Physical literacy, which includes the assessment of physical fitness, could be considered a crucial element for understanding adolescents’ health status and physical activity-related behaviours. Moreover, the self-perceived physical fitness should also be considered. Thus, this study analysed the relationship between physical literacy and self-perceived physical fitness in children and adolescents aged 8–12 years. It could be concluded that a higher level of self-perceived physical fitness would be associated with a greater level of physical literacy.

Abstract

Background: Physical fitness is considered a predictor of mortality and comorbidities resulting from physical inactivity in children and adolescents. Physical literacy provides a robust and comprehensive assessment of physical fitness. Thus, it is considered a crucial element for understanding children and adolescents’ health status and their physical activity-related behaviours. Moreover, the self-perceived fitness should also be considered. Therefore, this study aims to analyse the relationship between physical literacy and self-perceived physical fitness in children and adolescents aged 8–12 years. Methods: A single-measure cross-sectional study was conducted with 135 children and adolescents. Anthropometric measurements and the Canadian Assessment of Physical Literacy Development (CAPL-2) were applied. Descriptive statistics and correlations were calculated. The Fitness Perception Scale for Adolescents (FP VAS A) scale was also administered to assess participants’ self-perceived fitness. Results: Moderate significant correlations were found between “physical competence”, “motivation and confidence”, and the total CAPL-2 score with FP VAS A. Conclusions: The influence of motivation on self-perceived fitness has been demonstrated. Moreover, cardiorespiratory fitness could be considered one of the most relevant and influential factors in the total CAPL-2 score. It means that higher levels of self-perceived fitness would be associated with greater levels of physical literacy.

Obesity and Cardiometabolic Risk Factors: From Childhood to Adulthood

Obesity has become a major epidemic in the 21st century. It increases the risk of dyslipidemia, hypertension, and type 2 diabetes, which are known cardiometabolic risk factors and components of the metabolic syndrome. Although overt cardiovascular (CV) diseases such as stroke or myocardial infarction are the domain of adulthood, it is evident that the CV continuum begins very early in life. Recognition of risk factors and early stages of CV damage, at a time when these processes are still reversible, and the development of prevention strategies are major pillars in reducing CV morbidity and mortality in the general population. In this review, we will discuss the role of well-known but also novel risk factors linking obesity and increased CV risk from prenatal age to adulthood, including the role of perinatal factors, diet, nutrigenomics, and nutri-epigenetics, hyperuricemia, dyslipidemia, hypertension, and cardiorespiratory fitness. The importance of 'tracking' of these risk factors on adult CV health is highlighted and the economic impact of childhood obesity as well as preventive strategies are discussed.

Overweight/Obese Schoolchildren with Low Muscle Strength Have a Lower Cardiorespiratory Capacity and Greater Cardiovascular Risk: Results of the School Health Survey of the Extreme South of Chile 2019

Objective: To compare cardiovascular risk and cardiorespiratory capacity in schoolchildren from a region in the extreme south of Chile according to nutritional status and muscular strength. Methods: An analytical cross-sectional study was performed on a sample of 594 schoolchildren from 5th to 8th grade in the extreme south of Chile. Based on body mass index and lower limb muscle strength, participants were divided into four groups: high strength-normal weight, high strength-overweight/obese, low strength-normal weight, and low strength-overweight/obese. Then, waist-to-height ratio and cardiorespiratory capacity, measured with the 20 m shuttle run test, were assessed to determine their cardiovascular risk, comparing the four groups. Results: The overweight/obese group with high muscular strength presented better indicators in anthropometric variables (waist circumference and waist-to-height ratio) than their peers with low muscular strength. Additionally, the overweight/obese group with low muscular strength presented a lower cardiorespiratory capacity than their peers with high muscular strength. Both results were observed in boys and girls. Conclusion: The results of this study suggest that overweight/obese schoolchildren with high muscle strength present healthier anthropometric indicators and greater cardiorespiratory capacity than their peers with low muscle strength. These results confirm the relevance of measuring muscle strength in schoolchildren and its usefulness to assess functionality. These results encourage the scientific community to continue studying the role that muscle strength plays in modulating the effects of overweight and obesity on respiratory and cardiovascular conditions in childhood.

Levels of Physical Activity and Their Relationship With Motivational Determinants, Self-Regulation, and Other Health-Related Parameters in University Students

Motivational processes and emotional self-regulation are relevant factors for predicting the practice of physical exercise and for certain health-related parameters. The aim of the present work, developed along two different phases, was, on the one hand, to determine the prevalence of physical inactivity and, on the other hand, to carry out a comparative analysis between physically active and inactive university students in relation to their motivational determinants, emotional self-regulation, physical condition, health-related quality of life and other health parameters. The results obtained showed a prevalence of physical inactivity of 12.78%. Physically inactive participants showed significantly lower scores in intrinsic motivation, emotion regulation, and in some dimensions of health-related quality of life, as well as significantly high levels of body fat mass. Lastly, logistic regression analysis identified low scores in Emotional Clarity (p= .009) and Identified Regulation (p = .011), and high scores in Amotivation (p = .006) as reliable predictors of a physically inactive lifestyle. These results are useful for the design and implementation of programs aimed at promoting health and physical activity, with special attention on physically inactive youth populations.

Association between muscle strength and risk factors for metabolic syndrome in children and adolescents: a systematic review

The aim of this systematic review was to identify and summarize evidence for the association between muscle strength (MS) and metabolic syndrome (MetS), and MS and combinations of risk factors for MetS in children and adolescents. Five databases (Medline/PubMed, EBSCO, Scielo, Scopus, and Web of Knowledge) were searched up to November 2019 with complementary reference list searches. Inclusion criteria were studies that investigated the relationship between MS and MetS or MS and combinations of risk factors for MetS in children and adolescents (≤19 years of age). Risk of bias was assessed using standard procedures. From the total of 15,599 articles initially identified, 13 articles were included, representing 11,641 children and adolescents. Higher MS values were associated with lower risk for MetS or combinations of risk factors for MetS (n=11/13 studies). Of the total of included studies, about 23.1% (03/13) were longitudinal and all included studies were classified as having a moderate risk of bias. This review provides preliminary evidence for a beneficial relationship between MS and MetS among children and adolescents. Additionally, although the body of evidence points to the beneficial relationship between higher MS and lower risk for combination of factors for MetS in children and adolescents, this relationship is inconclusive.

Muscular Strength of Upper and Lower Limbs and Self-Esteem in Chilean SchoolChildren: Independent Associations with Body Composition Indicators

The aim of this study was to analyze the relationship between muscular strength from upper and lower limbs with self-esteem among Chilean schoolchildren, drawing independent associations with body composition indicators. The sample consisted of 1078 schoolchildren. The muscular strength of the upper and lower limbs was evaluated using a digital dynamometer and long jump performance. The general strength index was calculated based on Z-score values. Rosenberg’s test was used to determine the level of self-esteem of participants. Body fat and body mass index were employed as body composition indicators. Boys had significantly more upper and lower strength, and a general strength index higher than girls (11.7 vs. 10.6; 109.7 vs. 97.4; 0.19 vs. −0.24, respectively). For boys and girls combined, there were no significant associations between all muscular strength variables and self-esteem. In boys, upper and lower limb strength was positively associated with self-esteem. In girls, no association between muscular strength and self-esteem was found. In both sexes, the general strength index was not associated with self-esteem. Strategies and programs that promote mental health and muscular strength among schoolchildren, specifically in boys, are needed.

The reciprocal relationship between body mass index categories and physical fitness: A 4-year prospective cohort study of 20 000 Chinese children

INTRODUCTION

Body mass index (BMI) categories and physical fitness are associated but the reciprocal relationship between BMI categories and physical fitness has not been investigated. This study aims to investigate the longitudinal reciprocal relationship between BMI categories and physical fitness.

METHODS

This is a population-based 4-year cohort study in 48 elementary schools. Children aged 6 to 9 years at recruitment were included. BMI categories and physical fitness including handgrip strength, core muscle endurance, flexibility, and cardiorespiratory fitness were measured using standard equipment and protocol.

RESULTS

Among 26 392 eligible participants, 19 504 (73.9%) were successfully followed for 3 years. Baseline obesity prevalence was 5.9%. After 3 years, those who were unfit at baseline had an increased risk of obesity (risk ratio [RR] 1.41, 95% CI 1.16-1.71, P < .001) and those who were fit at baseline had a decreased risk of obesity (RR 0.69, 95% CI 0.60-0.80, P < .001) compared with moderately fit children. Furthermore, improvement of fitness predicted decreased risk of obesity. Similarly, normal body weight also predicted better physical fitness. The path analysis confirmed a strong reciprocal relationship between physical fitness and obesity.

CONCLUSIONS

Better physical fitness was prospectively associated with normal weight and vice versa. Physically fit children were more likely to maintain a healthy weight and those with a healthy weight were more likely to be physically fit, which is important for healthy development.

Cardiorespiratory Fitness as a Mediator of the Association between Physical Activity and Overweight and Obesity in Adolescent Girls

Background: Overweight and obesity (OW/OB) continue to be prominent health issues among adolescent girls. However, little is known about the interrelationships between physical activity (PA), cardiorespiratory fitness (CRF), and OW/OB in this population. The objective of this study was to examine whether CRF mediates the relationship between PA and OW/OB in adolescent girls. Methods: Moderate-to-vigorous PA (MVPA), CRF, BMI, and percentage body fat (% BF) were measured in adolescent girls (N = 1519), aged 10-14 years, from 24 urban middle schools located in the Midwestern United States. Structural equation modeling was used to determine whether CRF is a mediator of the association between MVPA and OW/OB (measured as both BMI and % BF). Multigroup analyses were used to determine whether race, puberty, or socioeconomic status moderate the mediation models. Results: The indirect effect of MVPA through CRF on OW/OB was significant for both BMI (p < 0.01) and % BF (p < 0.01), indicating that CRF is a complete mediator between MVPA and OW/OB. Both race and puberty significantly (p < 0.05) moderated the mediation between MVPA and OW/OB. Conclusions: This study demonstrates that CRF is improved by increasing MVPA, and the improvement in CRF results in lower BMI and % BF among adolescent girls.

Associations between Muscle Strength with Different Measures of Obesity and Lipid Profiles in Men and Women: Results from RaNCD Cohort Study

We aimed to examine associations between muscle strength and obesity and serum lipid profile in Ravansar Non-Communicable Disease (RaNCD) cohort study. This study was conducted on 6,455 subjects aged 35–65 years old from baseline data of RaNCD in Iran. The associations between grip strength and adiposity measurements were explored using linear regression with adjustment for age, height, smoking status, alcohol intake, social class, and prevalent disease. The mean of body mass index (BMI) and muscle strength was 27.2 ± 4.6 kg/m² and 33.3 ± 11.5, respectively. Muscular strength increased with increasing BMI and waist circumference (WC) in both sexes. Multivariate regression analysis revealed a 3.24 (95% confidence interval [CI], 2.29, 4.19) kg difference between BMI in top and bottom in men, and 1.71 (95% CI, 0.98, 2.34) kg/m² in women. After multivariable adjustment, a difference of 2.04 (95% CI, 1.12, 2.97) kg was observed between the top and bottom WC quartiles in men and 1.25 (95% CI, 0.51, 1.98) kg in women. In men, with increase of low-density lipoprotein and cholesterol, the mean muscle strength was significantly increased. Muscle strength may be associated with body composition and lipid profiles. Muscle strength can be an appropriate indicator for predicting some of the problems caused by body composition disorders, which requires further longitudinal studies.

What Do We Know about Diet and Markers of Cardiovascular Health in Children: A Review

Chronic diseases such as cancer, diabetes, and cardiovascular diseases (CVD) are the main health concerns in the 21st century, with CVD as the number one cause of mortality worldwide. Although CVD hard endpoints such as stroke or heart attack do not usually occur in children, evidence shows that the manifestation of CVD risk factors begins in childhood, preceding clinical complications of CVD in adulthood. Dietary intake is a modifiable risk factor that has been shown to make a substantial contribution to the risk of CVD in adulthood. However, less is known about the association between dietary intake and markers of cardiovascular health in children. This review summarises the current evidence on the relationship between dietary intake and markers of cardiovascular health including traditional CVD risk factors, physical fitness, and indices of arterial stiffness and wave reflection in children. Original research published in English, between January 2008 and December 2018 fulfilling the objective of this review were screened and included. Findings show that adaptation of a healthy lifestyle early in life can be beneficial for reducing the risk of CVD later in life. Furthermore, keeping arterial stiffness low from a young age could be a potential CVD prevention strategy. However, limited studies are available on diet-arterial stiffness relationship in children, and future research is required to better understand this association to aid the development and implementation of evidence-based strategies for preventing CVD-related complications later in life.

Association of Muscular Fitness and Body Fatness with Cardiometabolic Risk Factors: The FUPRECOL Study

This study investigated the associations of muscular fitness and various indicators of body fatness with cardio-metabolic risk factors and determined the muscular strength and body fatness thresholds for detecting a high risk of cardio-metabolic dysfunction in young adults. A cross-sectional study was conducted on 1798 collegiate students (61.5% females, mean age 20.5 years). Muscular fitness was determined by using a handgrip strength test and normalized grip strength (NGS = handgrip (kg)/body mass (kg)). Body mass index (BMI), waist circumference (WC), percentage of fat mass (BF%), fat-mass index (FMI), and waist-to-height ratio (WHR) were also included as body fatness measurements. A high cardio-metabolic risk cluster was derived by assessing triglycerides, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, fasting glucose, and blood pressure. Logistic regression models showed that men and women with lower NGS had an increased cardio-metabolic risk odds ratio (OR) = 1.8, 95% confidence interval (CI) 1.1 to 2.9, p = 0.006, and OR = 1.6, 95% CI 1.0 to 2.5, p = 0.036, respectively). In both sexes, higher levels of all fatness parameters were also associated with increased cardio-metabolic risk (p < 0.001). In both men and women, high FMI had the highest OR for clustered risk (OR = 4.7, 95% CI 2.6 to 8.4, and OR = 7.3, 95% CI 3.4 to 9.7, p < 0.001, respectively). Combined analysis showed that unfitness (lower NGS) and high fat had the highest OR for WC and FMI in men and women, respectively (OR = 5.5, 95% CI 2.6 to 11.4, OR = 7.7, 95% CI 2.3 to 15.8, p < 0.01). Muscular strength and body fatness are independently and jointly associated with increased cardiometabolic risk in young adults, which suggests that both are predictor variables for this.

30-year changes in Australian children's standing broad jump: 1985-2015

OBJECTIVES

Muscular strength is an important component of fitness that enables the execution of a range of daily activities across the lifespan including sport participation. The purpose of this study was to examine changes in children's standing broad jump, an indicator of muscular strength, between 1985 and 2015.

DESIGN

Two representative cross-sectional population surveys of Australian children age 9-15 years (n=7051).

METHODS

In 1985 and 2015 children's standing broad jump (SBJ; cm) and anthropometry were measured by trained field teams. General linear regression examined the temporal change in SBJ by sex and age adjusting for height, weight, socioeconomic status, and linguistic background.

RESULTS

Over a 30-year period, the height, weight, and BMI of children significantly increased and muscular strength decreased. Among boys, the adjusted SBJ distance declined -4.5cms (95%CI -8.8, -0.10) in 9-11 year olds and 7.6cms (95%CI -12.5, -2.7) in 12-15 year olds. Among girls, the adjusted SBJ distance declined 8.5cms (95%CI -12.9, -4.2) in 9-11 year olds and 9.3cms (95%CI -14.1, -4.6) in 12-15 year olds. Larger declines in the distance jumped were observed among children and adolescents from non-English speaking backgrounds, than English speaking peers and children from low socioeconomic neighbourhoods than the declines among children from high SES neighbourhoods.

CONCLUSIONS

Overall, the distance children and adolescents jumped in 2015 was lower than the distance their peers jumped in 1985. The declines differed by sex and sociodemographic characteristics, which suggests targeted sub-population interventions to improve children's muscular strength should be considered.

Effectiveness of a school-based program focusing on diet and health habits taught through physical exercise

The global rate of obesity in childhood is becoming an epidemic and many authors have established a significant association between childhood obesity and overweight in adulthood. It is therefore necessary to seek effective strategies to reduce these levels of obesity. The aim of this study was to evaluate the impact of the Healthy Habits Program (HHP). The participants comprised 158 children from the fifth and sixth grades (intervention group, n = 82; control group, n = 76). The HHP is a school-based physical activity program focusing on promoting a healthy lifestyle. It lasted for 8 months, and measurements were taken at the beginning and end of the program. Physiological variables (total cholesterol, triglycerides, blood glucose, blood pressure, and maximal oxygen consumption), anthropometric variables (body mass index (BMI)) and behavioral variables (breakfast, quality of diet, meal frequency, physical activity, sedentary behavior, sleep, and perceived health) were evaluated. Repeated-measures ANOVA showed significant improvements (p < 0.05) after the intervention for the intervention group in triglycerides, blood glucose and maximal oxygen consumption. Significant improvements were also observed in breakfast habits and quality of diet. Finally, a significant improvement in prevalence of normal levels was observed for total cholesterol, blood pressure, and BMI. It can therefore be stated that the HHP is an innovative and useful school-based program that can help to improve diet and health in childhood.

Low muscle mass is associated with cardiometabolic risk regardless of nutritional status in adolescents: A cross-sectional study in a Chilean birth cohort

BACKGROUND

Increased cardiometabolic risk (CMR) is documented in obese and non-obese adolescents with low muscular fitness. However, the association of low muscle mass (LMM) with CMR, independent of weight status, has not been examined. We analyzed the relationship of LMM with CMR in adolescents, regardless of their weight status.

MATERIALS AND METHODS

Observational study in 660 adolescents. BMI, waist circumference (WC), arterial blood pressures (ABP) were measured. Total fat mass (TFM), total lean tissue (TLT), and appendicular skeletal muscle mass (ASM) were estimated (DXA). Fasting lipid profile, glucose, and insulin were measured. HOMA-IR was estimated. Metabolic Syndrome (MetS) was diagnosed (AHA/NHLBI/IDF). ROC analysis was performed to find the optimal cutoffs of TLT percentage for MetS diagnosis. Values below these cutoffs defined LMM. ANCOVA examined the association of LMM with selected cardiometabolic biomarkers.

RESULTS

In both sexes, TLT showed better sensitivity and specificity than ASM for MetS diagnosis. In males and females, TLT of 66.1% and 56.3%, respectively, were the optimal cutoff for MetS diagnosis. In the sample, 17.3% of males and 23.7% of females had LMM. In both sexes, adolescents with LMM had significantly higher values of WC, ABP, TG, TC/HDL, HOMA-IR, and MetS z-score than non-LMM participants. Adolescents with LMM, regardless nutritional status, had significantly increased values of MetS z-score, ABP, TG, TC/HDL-chol, and HOMA-IR than non-obese non-LMM adolescents. Adolescents having both obesity and LMM had the unhealthiest CMR profile.

CONCLUSION

In adolescents, LMM was associated with higher CMR, regardless of nutritional status. In obese adolescents, LMM increased obesity-associated CMR.

Sarcopenia and Predictors of Skeletal Muscle Mass in Elderly Men With and Without Obesity

Objectives: The aim of this study was to determine the variables which show the highest association with muscle mass and to identify the most important predictors for muscle mass in elderly men with and without sarcopenia. Methods: A total of 71 men participated, aged ≥65 years. Sarcopenia was assessed using the definition of the European Working Group on Sarcopenia in Older People with determining skeletal muscle index (SMI), hand-grip strength (HGS), and Short Physical Performance Battery. In addition, maximum strength at upper and lower extremities and physical activity were measured. Results: Strong correlations existed between SMI and gait speed, HGS, maximum isometric strength at leg and chest press. Physical activity showed low correlations with muscle strength. Regression analysis revealed HGS and gait speed as key predictors for SMI. Discussion: The recommendation is measuring gait speed and HGS in clinical practice at first followed by measuring muscle mass for determining sarcopenia.

Changes in physical fitness of a home-based physical exercise program in childhood obesity: A quasi-experimental uncontrolled study

Few studies have evaluated the changes in physical fitness (PF) of obese children and adolescents of a physical activity program for the treatment of obesity, and even fewer have explored the modality of home-based physical exercise. The objective of this study is to evaluate the changes in PF and body composition (BC) of a home-based physical exercise for treating childhood obesity. Thirty-three overweight/obese children and adolescents participated for six months in a home-based intervention that combined aerobics and muscular strength exercises. The results were compared, before and after the intervention, for the different PF components (VO2_max, abdominal muscle resistance strength, and lower body explosive strength) and BC (body mass index Z-score (BMI-Z), percentage of body fat, and fat-free mass) variables. A significant reduction was observed in the percentage of body fat (4.7%) and the BMI- Z score (.23), and there was an increase in the fat-free mass of 2.9 kg ( p < .001). In addition, the VO2_max showed a significant increase ( p < .05). The results of the different strength tests also showed significant improvements ( p < .05). Our findings support the effectiveness of this program improving not only BC but also PF. However, our results should be interpreted with caution due to lack of control group.

Associations between physical activity, screen time, and fitness among 6- to 10-year-old children living in Edmonton, Canada

The objectives of this study were to describe fitness levels; examine associations between physical activity (PA), screen time (ST), and fitness; and examine sex-moderating effects in a sample of children. Participants were 649 children (age, 7.8 ± 0.6 years; 52.4% female) from Edmonton, Canada. Hours/week of PA and ST were parent-reported. PA was also objectively measured with pedometers and expressed in increments of 1000 steps/day. Fitness components (i.e., vertical jump, sit-and-reach, waist circumference, grip strength, predicted maximal oxygen consumption, push-ups, partial curl-ups, overall fitness) were measured according to the Canadian Physical Activity, Fitness, and Lifestyle Approach protocols and expressed as z scores or low/high fitness. Positive associations were observed between PA and overall fitness for both the complete (subjective: β = 0.009, 95% confidence interval (CI): 0.001-0.017) and partial (≥3 available fitness measures; subjective: β = 0.006, 95% CI: 0.000-0.011; objective: β = 0.025, 95% CI: 0.007-0.042) fitness scores. Subjective (β = 0.011, 95% CI: 0.000-0.022) and objective (β = 0.043, 95% CI: 0.008-0.078) PAs were positively associated with vertical jump. Children with higher objective PA were more likely to be in the high push-ups group (odds ratio = 1.156, 95% CI: 1.054-1.267). PA was positively associated with predicted maximal oxygen uptake (subjective: β = 0.040, 95% CI: 0.018-0.063; objective: β = 0.084, 95% CI: 0.012-0.157) and grip strength (subjective: β = 0.025, 95% CI: 0.011-0.040) in boys only. ST was negatively associated with grip strength (β = -0.016, 95% CI: -0.028 to -0.004) in boys. PA was associated with several components of fitness, especially in boys. However, few associations were observed between ST and fitness. Promoting regular PA in young children may address declining fitness levels.

Condición física y calidad de vida en escolares de 8 a 12 años

Introducción. La condición física (CF) es un importante indicador fisiológico del estado de salud de la población en general y de los escolares en particular.Objetivo. Analizar la relación entre CF y calidad de vida (CV) en una muestra de escolares de primaria.Materiales y métodos. Estudio transversal en el que participaron 298 escolares (159 mujeres y 139 varones) de entre 8 y 12 años de la región de Murcia, en España, durante el periodo 2013-2014. La CF se valoró mediante la batería ALPHA-fitness y su nivel (bajo, medio y alto) fue categorizado con base en estudios previos, la CV se valoró mediante el cuestionario KIDSCREEN-10 Index y para establecer la relación entre ambas variables se realizó un análisis de varianza simple.Resultados. El valor global de la CF se asoció de manera positiva con la CV (F=3.997; p=0.019).Conclusiones. Los resultados sugieren que los escolares con un mejor estado de CF tienen una mayor CV. Se precisan estudios de intervención dirigidos al desarrollo de la CF para evaluar las posibles mejoras en los niveles de CV de los jóvenes.

High muscular fitness has a powerful protective cardiometabolic effect in adults: influence of weight status

BACKGROUND

Low levels of muscular fitness (MF) are recognized as an important marker of nutritional status and a predictor of metabolic complications, cardiovascular disease and death, however, the relationship between MF, body mass index (BMI) and the subsequent cardiometabolic protective effects has been less studied among Latin American populations. This study identified an association between MF and the cardiometabolic risk score index (CMRSI) and the lipid-metabolic cardiovascular risk index (LMCRI) in a wide sample of university students grouped according to their BMI.

METHODS

Six thousand ninety five healthy males (29.6 ± 11.7 year-old) participated in the study. Absolute strength was measured using a T.K.K. analogue dynamometer (handgrip), and the participant's strength was then calculated relative to their body mass (MF/BM). The LMCRI was derived from the levels of triglycerides, low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), and glucose levels in a blood sample. The CMRSI was calculated by summing the standardized residuals (z-score) for waist circumference, total cholesterol, LDL-c, triglycerides, HDL-c, and median blood pressure. Subjects were divided into six subgroups according to BMI (normal vs. overweight/obese) and MF/BM tertiles (unfit, average, fit).

RESULTS

The group of participants with low and moderate levels of MF/BM showed higher CMRSI values independent of BMI (P < 0.001). The group with normal BMI and high MF/BM had the highest levels of cardiometabolic protection. All overweight/obese BMI groups had significantly higher LMCRI values independent of the level of MF/BM (P < 0.001).

CONCLUSIONS

Participants with high MF/BM showed reduced cardiometabolic risk, which increased significantly when they were within normal parameters.

[Analysis of the reliability and validity of three self-report questionnaires to assess physical activity among Spanish adolescents]

OBJECTIVE

To analyse the reliability and validity of the Weekly Activity Checklist (WAC), the One Week Recall (OWR), and the Godin-Shephard Leisure Time Exercise Questionnaire (GLTEQ) in Spanish adolescents.

METHODS

A total of 78 adolescents wore a pedometer for one week, filled out the questionnaires at the end of this period and underwent a test to estimate their maximal oxygen consumption (VO2max). The reliability of the questionnaires was determined by means of a factor analysis. Convergent validity was obtained by comparing the questionnaires' scores against the amount of physical activity quantified by the pedometer and the VO2max reported.

RESULTS

The questionnaires showed a weak internal consistency (WAC: α=0.59-0.78; OWR: α=0.53-0.73; GLTEQ: α=0.60). Moderate statistically significant correlations were found between the pedometer and the WAC (r=0.69; p <0.01) and the OWR (r=0.42; p <0.01), while a low statistically significant correlation was found for the GLTEQ (r=0.36; p=0.01). The estimated VO2max showed a low level of association with the WAC results (r=0.30; p <0.05), and the OWR results (r=0.29; p <0.05). When classifying the participants as active or inactive, the level of agreement with the pedometer was moderate for the WAC (k=0.46) and the OWR (r=0.44), and slight for the GLTEQ (r=0.20).

CONCLUSION

Of the three questionnaires analysed, the WAC showed the best psychometric performance as it was the only one with respectable convergent validity, while sharing low reliability with the OWR and the GLTEQ.

Influence of physical fitness on cardio-metabolic risk factors in European children. The IDEFICS study

OBJECTIVE

The aim of the study was to assess the associations of individual and combined physical fitness components with single and clustering of cardio-metabolic risk factors in children.

SUBJECTS/METHODS

This 2-year longitudinal study included a total of 1635 European children aged 6-11 years. The test battery included cardio-respiratory fitness (20-m shuttle run test), upper-limb strength (handgrip test), lower-limb strength (standing long jump test), balance (flamingo test), flexibility (back-saver sit-and-reach) and speed (40-m sprint test). Metabolic risk was assessed through z-score standardization using four components: waist circumference, blood pressure (systolic and diastolic), blood lipids (triglycerides and high-density lipoprotein) and insulin resistance (homeostasis model assessment). Mixed model regression analyses were adjusted for sex, age, parental education, sugar and fat intake, and body mass index.

RESULTS

Physical fitness was inversely associated with clustered metabolic risk (P<0.001). All coefficients showed a higher clustered metabolic risk with lower physical fitness, except for upper-limb strength (β=0.057; P=0.002) where the opposite association was found. Cardio-respiratory fitness (β=-0.124; P<0.001) and lower-limb strength (β=-0.076; P=0.002) were the most important longitudinal determinants. The effects of cardio-respiratory fitness were even independent of the amount of vigorous-to-moderate activity (β=-0.059; P=0.029). Among all the metabolic risk components, blood pressure seemed not well predicted by physical fitness, while waist circumference, blood lipids and insulin resistance all seemed significantly predicted by physical fitness.

CONCLUSION

Poor physical fitness in children is associated with the development of cardio-metabolic risk factors. Based on our results, this risk might be modified by improving mainly cardio-respiratory fitness and lower-limb muscular strength.

Differences in Adolescent Physical Fitness: A Multivariate Approach and Meta-analysis

Physical fitness can be defined as a set of components that determine exercise ability and influence performance in sports. This study investigates the genetic and environmental influences on individual differences in explosive leg strength (vertical jump), handgrip strength, balance, and flexibility (sit-and-reach) in 227 healthy monozygotic and dizygotic twin pairs and 38 of their singleton siblings (mean age 17.2 ± 1.2). Heritability estimates were 49 % (95 % CI 35–60 %) for vertical jump, 59 % (95 % CI 46–69 %) for handgrip strength, 38 % (95 % CI 22–52 %) for balance, and 77 % (95 % CI 69–83 %) for flexibility. In addition, a meta-analysis was performed on all twin studies in children, adolescents and young adults reporting heritability estimates for these phenotypes. Fifteen studies, including results from our own study, were meta-analyzed by computing the weighted average heritability. This showed that genetic factors explained most of the variance in vertical jump (62 %; 95 % CI 47–77 %, N = 874), handgrip strength (63 %; 95 % CI 47–73 %, N = 4516) and flexibility (50 %; 95 % CI 38–61 %, N = 1130) in children and young adults. For balance this was 35 % (95 % CI 19–51 %, N = 978). Finally, multivariate modeling showed that the phenotypic correlations between the phenotypes in current study (0.07 < r < 0.27) were mostly driven by genetic factors. It is concluded that genetic factors contribute significantly to the variance in muscle strength, flexibility and balance; factors that may play a key role in the individual differences in adolescent exercise ability and sports performance.

The health benefits of muscular fitness for children and adolescents: a systematic review and meta-analysis

BACKGROUND

Physical fitness during childhood and adolescence has been identified as an important determinant of current and future health status. While research has traditionally focused on the association between cardio-respiratory fitness and health outcomes, the association between muscular fitness (MF) and health status has recently received increased attention.

OBJECTIVE

The aim of this systematic review and meta-analysis was to evaluate the potential physiological and psychological benefits associated with MF among children and adolescents.

METHODS

A systematic search of six electronic databases (PubMed, SPORTDiscus, Scopus, EMBASE, PsycINFO and OVID MEDLINE) was performed on the 20th May, 2013. Cross-sectional, longitudinal and experimental studies that quantitatively examined the association between MF and potential health benefits among children and adolescents were included. The search yielded 110 eligible studies, encompassing six health outcomes (i.e., adiposity, bone health, cardiovascular disease [CVD] and metabolic risk factors, musculoskeletal pain, psychological health and cognitive ability). The percentage of studies reporting statistically significant associations between MF and the outcome of interest was used to determine the strength of the evidence for an association and additional coding was conducted to account for risk of bias. Meta-analyses were also performed to determine the pooled effect size if there were at least three studies providing standardised coefficients.

RESULTS

Strong evidence was found for an inverse association between MF and total and central adiposity, and CVD and metabolic risk factors. The pooled effect size for the relationship between MF and adiposity was r = -0.25 (95% CI -0.41 to -0.08). Strong evidence was also found for a positive association between MF and bone health and self-esteem. The pooled effect size for the relationship between MF and perceived sports competence was r = 0.39 (95% CI 0.34-0.45). The evidence for an association between MF and musculoskeletal pain and cognitive ability was inconsistent/uncertain. Where evidence of an association was found, the associations were generally low to moderate.

CONCLUSION

The findings of this review highlight the importance of developing MF in youth for a number of health-related benefits.

BMI as a mediator of the relationship between muscular fitness and cardiometabolic risk in children: a mediation analysis

Objective

Muscular fitness levels have been associated with cardiometabolic risk in children, although whether body weight acts as a confounder or as an intermediate variable in this relationship remains controversial. The aim of this study was to examine whether the association between muscular fitness and cardiometabolic risk factors is mediated by body mass index (BMI).

Design and Methods

Cross-sectional study using a sample of 1158 schoolchildren aged 8-11 years from the province of Cuenca, Spain. We measured anthropometrics and biochemical variables and we calculated a muscular fitness index as the sum of z-scores of handgrip dynamometry/weight and standing long jump, and we estimated a previously validated cardiometabolic risk index (CMRI). Linear regression models were fitted for mediation analysis to assess whether the association between muscular fitness and cardiometabolic risk was mediated by BMI.

Results

Children with normal weight (NW) had a better cardiometabolic risk profile than their overweight (OW) or obese (OB) peers after controlling for muscular fitness. Marginal estimated mean±SE values for NW, OW and OB categories of CMRI were -0.75±0.06<0.84±0.10<2.18±0.16 in boys and -0.73±0.06<0.96±0.10<2.71±0.17 in girls, both p<0.001. Children with higher levels of muscular fitness had a better cardiometabolic risk profile (CMRI marginal estimated mean±SE 1.04±0.13>0.05±0.09>-1.16±0.13 for lower, middle and upper quartiles of muscular fitness in boys and 1.01±0.16>0.10±0.09>-1.02±0.15 in girls, both p<0.001), but differences disappeared when controlling for BMI. BMI acted as a full mediator between muscular fitness and most cardiometabolic risk factors (Sobel test z=-11.44 for boys; z=-11.83 for girls; p<0.001 in CMRI mediation model) and as a partial mediator in the case of waist circumference (Sobel test z=-14.86 for boys; z=-14.51 for girls; p<0.001).

Conclusions

BMI mediates the association between muscular fitness and cardiometabolic risk in schoolchildren. Overall, good muscular fitness is associated with lower cardiometabolic risk, but particularly when accompanied by normal weight.

Current Evidence for the Impact of Physical Fitness on Health Outcomes in Youth

Physical fitness is tightly linked to our ability to be physically active, and poor fitness is tied to increased risk of lifestyle diseases such as diabetes and cardiovascular disease in adulthood. In 2011, the Institute of Medicine appointed an expert committee to review the evidence between physical fitness and health outcomes in youth. Specifically, experimental and longitudinal studies published between 2000 and 2010 were reviewed in the areas of body composition, cardiorespiratory fitness, musculoskeletal fitness, and flexibility. Specific fitness tests that were linked to health risk factors or health outcomes in each of these areas were identified. Recommendations for the best fitness test items for use in schools and also for a national survey were given. In addition, guidance was provided for interpretation of fitness test scores along with recommendations for areas of needed future research. Key findings from the final report “Fitness Measures and Health Outcomes in Youth” will be reviewed.

Physical fitness among urban and rural Ecuadorian adolescents and its association with blood lipids: a cross sectional study

BACKGROUND

Physical fitness has been proposed as a marker for health during adolescence. Currently, little is known about physical fitness and its association with blood lipid profile in adolescents from low and middle-income countries. The aim of this study is therefore to assess physical fitness among urban and rural adolescents and its associations with blood lipid profile in a middle-income country.

METHODS

A cross-sectional study was conducted between January 2008 and April 2009 in 648 Ecuadorian adolescents (52.3% boys), aged 11 to 15 years, attending secondary schools in Cuenca (urban n = 490) and Nabón (rural n = 158). Data collection included anthropometric measures, application of the EUROFIT battery, dietary intake (2-day 24 h recall), socio-demographic characteristics, and blood samples from a subsample (n = 301). The FITNESGRAM standards were used to evaluate fitness. The associations of fitness and residential location with blood lipid profile were assessed by linear and logistic regression after adjusting for confounding factors.

RESULTS

The majority (59%) of the adolescents exhibited low levels of aerobic capacity as defined by the FITNESSGRAM standards. Urban adolescents had significantly higher mean scores in five EUROFIT tests (20 m shuttle, speed shuttle run, plate tapping, sit-up and vertical jump) and significantly most favorable improved plasma lipid profile (triglycerides and HDL) as compared to rural adolescents. There was a weak association between blood lipid profile and physical fitness in both urban and rural adolescents, even after adjustment for confounding factors.

CONCLUSIONS

Physical fitness, in our sample of Ecuadorian adolescents, was generally poor. Urban adolescents had better physical fitness and blood lipid profiles than rural adolescents. The differences in fitness did not explain those in blood lipid profile between urban and rural adolescents.

Strength capacity and cardiometabolic risk clustering in adolescents

OBJECTIVES

The purpose of this study was to determine the gender-specific independent association between muscular strength and cardiometabolic risk clustering in a large cohort (n = 1421) of children.

METHODS

Principal component analysis was used to determine the pattern of risk clustering and to derive a continuous aggregate score (MetScore) from various cardiometabolic risk components: percent body fat (%BF), fasting glucose, blood pressure, plasma triglycerides levels, and HDL-cholesterol. Gender-stratified risk and MetScore were assessed by using general linear models and logistic regression for differences between strength tertiles, as well as independent associations with age, BMI, estimated cardiorespiratory fitness (CRF), physical activity, and muscular strength (normalized for body mass).

RESULTS

In both boys (n = 670) and girls (n = 751), there were significant differences in cardiometabolic profiles across strength tertiles, such that stronger adolescents had lower overall risk. Age, BMI, cardiorespiratory fitness, physical activity participation, and strength were all individually correlated with multiple risk components, as well as the overall MetScore. However, in the adjusted model, only BMI (β = 0.30), physical inactivity (β = 0.30), and normalized strength capacity (β = -1.5) emerged as significant (P < .05) predictors of MetScore. %BF was the strongest loading coefficient within the principal component analysis-derived MetScore outcome.

CONCLUSIONS

Normalized strength is independently associated with lower cardiometabolic risk in boys and girls. Moreover, %BF was associated with all cardiometabolic risk factors and carried the strongest loading coefficient. These findings bolster the importance of early strength acquisition and healthy body composition in childhood.

Obesity as a mediator of the influence of cardiorespiratory fitness on cardiometabolic risk: a mediation analysis

OBJECTIVE

The relationship between cardiorespiratory fitness (CRF) and metabolic syndrome (MetS) is well known, although the extent to which body weight may act as a confounder or mediator in this relationship is uncertain. The aim of this study was to examine whether the association between CRF and cardiometabolic risk factors is mediated by BMI.

RESEARCH DESIGN AND METHODS

A cross-sectional study including 1,158 schoolchildren aged 8-11 years from the province of Cuenca, Spain, was undertaken. We measured height, weight, waist circumference (WC), blood pressure, fasting plasma lipid profile and insulin, and CRF (20-m shuttle run test). A validated cardiometabolic risk index was estimated by summing standardized z scores of WC, log triglyceride-to-HDL cholesterol ratio (TG/HDL-c), mean arterial pressure (MAP), and log fasting insulin. To assess whether the association between CRF and cardiometabolic risk was mediated by BMI, linear regression models were fitted according to Baron and Kenny procedures for mediation analysis.

RESULTS

In girls, BMI acts as a full mediator in the relationship between CRF and cardiometabolic risk factors, with the exception of log TG/HDL-c ratio. In boys, BMI acts as a full mediator in the relationship between CRF and both log TG/HDL-c ratio and MAP, and as a partial mediator in the relationship between CRF and cardiometabolic risk factors.

CONCLUSIONS

BMI mediates the association between CRF and MetS in schoolchildren. Overall, good levels of CRF are associated with lower cardiometabolic risk, particularly when accompanied by weight reduction.

Associations between health-related physical fitness and obesity in Taiwanese youth

This study examined associations between four health-related physical fitness measures and obesity in Taiwanese youth aged 10-18 years. Data from 13,500 school-aged youth were randomly selected from the "School Physical Fitness Database" of Taiwan by sex and age. Variables examined were height, body mass and performance on modified sit-and-reach (flexibility), bent-leg sit-up (abdominal muscular strength/endurance), standing long jump (lower body explosive strength) and distance run/walk (cardiorespiratory endurance). Adjusted logistic regression analyses were performed. Increased odds of being obese with decreased fitness levels were observed for lower body explosive strength and cardiorespiratory endurance in both sexes. The highest odds of being obese was found in the least fit quintile of cardiorespiratory endurance compared with the most fit quintile both in boys (Odds ratio, OR = 10.44; 95% confidence interval (CI), 7.94-13.73) and girls (OR = 5.40; 95% CI, 3.90-7.47). These findings suggest that in addition to cardiorespiratory fitness, lower body explosive strength is also associated with childhood and adolescent obesity.

[Association of muscle strength with early markers of cardiovascular risk in sedentary adults]

OBJECTIVE

To assess the association between muscle strength and early cardiovascular risk (CVR) markers in sedentary adults.

MATERIALS AND METHODS

A total of 176 sedentary subjects aged 18-30 years were enrolled. Body mass index and fat percentage were calculated, and waist circumference, grip strength by dynamometry, systolic blood pressure, diastolic blood pressure, mean arterial pressure, and maximal oxygen uptake by VO2max were measured as CVR markers. A multivariate logistic regression analysis was used to assess associations between muscle strength and CVR markers.

RESULTS

Inverse correlations were found between muscle strength and adiposity (r=-.317; P=.001), waist circumference (r=-.309; P=.001), systolic blood pressure (r=-.401; P=.001), and mean arterial pressure (r=-.256; P=.001). Subjects with lower levels of muscle strength had a 5.79-fold (95% CI 1.57 to 9.34; P=.008) risk of having higher adiposity levels (≥25%) and a 9.67-fold (95% CI=3.86 to 19.22; P<.001) risk of having lower physical capacity values for VO2max (≤31.5mL/kg/min(-1)).

CONCLUSIONS

In sedentary adults, muscle strength is associated to early manifestations of CVR. It is suggested that muscle strength testing is added to routine measurement of VO2max and traditional risk factors for prevention and treatment of cardiovascular risk.

Effects of muscular strength on cardiovascular risk factors and prognosis

Physical fitness is one of the strongest predictors of individual future health status. Together with cardiorespiratory fitness (CRF), muscular strength has been increasingly recognized in the pathogenesis and prevention of chronic disease. We review the most recent literature on the effect of muscular strength in the development of cardiovascular disease, with special interest in elucidating its specific benefits beyond those from CRF and body composition. Muscular strength has shown an independent protective effect on all-cause and cancer mortality in healthy middle-aged men, as well as in men with hypertension and patients with heart failure. It has also been inversely associated with age-related weight and adiposity gains, risk of hypertension, and prevalence and incidence of the metabolic syndrome. In children and adolescents, higher levels of muscular fitness have been inversely associated with insulin resistance, clustered cardiometabolic risk, and inflammatory proteins. Generally, the influence of muscular fitness was weakened but remained protective after considering CRF. Also, interestingly, higher levels of muscular fitness seems to some extent counteract the adverse cardiovascular profile of overweight and obese individuals. As many of the investigations have been conducted with non-Hispanic white men, it is important to examine how race/ethnicity and gender may affect these relationships. To conclude, most important effects of resistance training are also summarized, to better understand how higher levels of muscular fitness may result in a better cardiovascular prognosis and survival.

Evaluation of metabolic risk in prepubertal girls versus boys in relation to fitness and physical activity

BACKGROUND

Low levels of cardiorespiratory fitness (CRF) and physical activity (PA) are associated with a risk of the development of metabolic syndrome. Contradictory findings are reported in the literature regarding the influence of sex and CRF and PA on metabolic changes.

OBJECTIVE

The aim of this study was to analyze the effects of CRF and PA on lipid and carbohydrate metabolism biomarkers in boys and girls.

METHODS

A total of 82 prepubertal boys and 55 girls (7-12 years of age) were classified according to sex, low or high CRF, and performance or nonperformance of PA. Anthropometric and blood pressure (BP) measurements, plasma lipid profile values, glucose and insulin levels, and homeostasis model assessment for insulin resistance were analyzed.

RESULTS

The percentage of boys with high CRF and performance of PA was higher than that of girls (P < 0.05). When children of the same sex were compared, higher values for body mass index and waist circumference z-scores were found for boys with low CRF compared with boys with high CRF (P < 0.001) without differences between girls, and in all groups classified by PA. Systolic and diastolic BPs were higher in boys than in girls, in both CRF and PA groups (P < 0.05). In the low CRF and no PA groups, girls had higher plasma glucose, total cholesterol, and low-density lipoprotein cholesterol levels than boys, with higher high-density lipoprotein cholesterol and apolipoprotein A levels (P < 0.05).

CONCLUSIONS

Sex in relation to CRF and PA could affect the plasma lipid profile. These changes in girls are associated with low CRF and low levels of PA. Considering these results, we suggest the need to improve CRF and promote PA, especially in girls, to reduce metabolic risk.

The Association of Physical Fitness With Body Mass Index and Waist Circumference in Filipino Preadolescents

Aim. The objective of this study is are to examine the association of preadolescent obesity using body mass index (BMI) and waist circumference (WC) with health-related physical fitness components. Methods. Grades 4 to 6 students in 2 private schools in Manila were included in this study. Height, weight, WC, and BMI were obtained. Physical fitness field tests were sit-and-reach test, 1-minute sit-ups, standing broad jump, 40-m sprint, and 20-m shuttle run. Results. Obese subjects had poorer scores in the field tests except in the sit-and-reach test. BMI and WC were significantly negatively associated with all the physical fitness parameters, except for the 40-m sprint where positive correlation was observed, and in the sit-and-reach test where no correlation was seen. Conclusion. In the management of preadolescent overweight and obesity, exercise programs should therefore be designed toward enhancing these fitness parameters, while not sacrificing enjoyment and creativity.

Prepubertal children with suitable fitness and physical activity present reduced risk of oxidative stress

To assess the impact of fitness status and physical activity on oxidative stress in prepubertal children, we measured selected biomarkers such as protein carbonyls (PC), lipid peroxidation products, and total nitrites, as well as the antioxidant system: total glutathione (TG), oxidized glutathione (GSSG), reduced glutathione (GSH), superoxide dismutase activity, and glutathione peroxidase. A total of 132 healthy children ages 7-12, at prepubertal stage, were classified into two groups according to their fitness level: low fitness (LF) and high fitness (HF). They were observed while engaged in an after-school exercise program, and a questionnaire was created to obtain information on their physical activity or sedentary habits. Plasma and red blood cells were obtained to analyze biomarkers. Regarding oxidative stress markers, the LF group and the sedentary group showed higher levels of TG and GSSG and a lower GSH/GSSG ratio than the HF group and the children engaged in physical activity. A negative association was found between PC and GSSG and TG and between TG and the GSH/GSSG ratio. Moreover, a negative correlation was found between GSSG and fitness, with a positive correlation with the GSH/GSSG ratio. TG, GSSG, and the GSH/GSSG ratio seem to be reliable markers of oxidative stress in healthy prepubertal children with low fitness or sedentary habits. This research contributes to the recognition that an adequate level of fitness and recreational physical activity in childhood leads to better health and oxidative status.

Associations of physical activity and fitness with adipocytokines in adolescents: the AFINOS Study

BACKGROUND AND AIMS

Adipocytokines may have a key role in the development of atherosclerosis and type 2 diabetes. The purpose of this study was to examine the independent and joint associations of physical activity (PA), cardiorespiratory fitness (CRF) and muscular fitness (MF) with adiponectin and leptin in adolescents.

METHODS AND RESULTS

A sample of 198 adolescents (96 girls), aged 13-17-year, was selected. Participants completed anthropometric measurements (height, weight, and waist circumference) and percentage of body fat (%BF) was estimated by bioelectrical impedance. PA was measured by accelerometer for 7-day. The 20-m shuttle-run test was used to assess CRF and two MF tests (handgrip strength and standing broad jump) were used to create an MF score. A cluster score of health status (0-3 risks) was created. Serum adiponectin and plasma leptin were also determined. Regression analyses controlling for age, sex, pubertal status and waist circumference showed that PA was not significantly associated with adiponectin and vigorous PA showed a significant inverse association with leptin. Both CRF and MF were significantly and inversely associated with adiponectin and leptin. Further analyses revealed that the 'healthy' group (0 risks) had significantly lower adiponectin and leptin than 'medium-healthy' (1 risk) and 'unhealthy' (2-3 risks) status groups.

CONCLUSIONS

PA, CRF and MF are inversely and jointly associated with adiponectin and leptin concentrations in adolescents.

Non-traditional markers of metabolic risk in prepubertal children with different levels of cardiorespiratory fitness

OBJECTIVE

To assess classical and non-classical metabolic risk biomarkers in prepubertal children with different levels of cardiorespiratory fitness (CRF).

DESIGN

CRF was assessed by the 20 m shuttle run test. To estimate physical activity, participants were observed while engaged in an after-school programme. Additionally, a short test based on a validated questionnaire was used to obtain information about physical activity practice and sedentary habits. Anthropometric parameters, blood pressure, and classical and non-traditional metabolic risk biomarkers--plasma lipid profile, glucose and insulin, homeostasis model assessment-insulin resistance index (HOMA-IR), plasma uric acid, transaminases and C-reactive protein (CRP)--were measured.

SETTING

The study was conducted in local elementary schools in Córdoba, Spain.

SUBJECTS

One hundred and forty-one healthy children (eighty-eight boys, fifty-three girls) aged 7-12 years, in Tanner stage I, were recruited. They were divided into two groups after they performed the 20 m shuttle run test: equal or higher cardiovascular fitness (EHCF) group and low cardiovascular fitness (LCF) group.

RESULTS

The LCF group displayed significantly higher TAG (P = 0.004) and lower HDL cholesterol levels (P = 0.001), as well as significantly lower values for the non-traditional lipid marker apo-A1 (P = 0.001) compared with the EHCF group. The LCF children displayed higher plasma glucose (P = 0.003) and insulin levels, higher HOMA-IR scores (P < 0.001) and higher plasma uric acid and CRP levels (P < 0.05). After adjustment for BMI, age and sex, no statistically significant differences were found between groups for the biomarkers analysed.

CONCLUSIONS

The study provides new information to understand the role not only of weight status but also of the level of CRF on the metabolic health profile of prepubertal children.