Field-Based Health-Related Physical Fitness Tests in Children and Adolescents: A Systematic Review

Could BIA-derived phase angle predict health-related musculoskeletal fitness? A cross-sectional study in young adults

OBJECTIVES

To our knowledge, little evidence exists on the relationships between body composition and health-related physical fitness; in particular, musculoskeletal fitness. Bioimpedance index phase angle (bioelectrical impedance analysis raw variables) is a candidate predictor of health-related fitness, a marker of fat-free and body cell mass, respectively. The aim of this study was to evaluate body composition, raw bioelectrical impedance analysis variables, and health-related fitness in young adults and investigate their mutual relationships to identify predictors of muscle strength.

METHODS

The study included 229 young adults (115 men and 114 women; 24.2 ± 3 y; body mass index 19-30 kg/m²). Anthropometry was measured with standardized procedures. Whole-body BIA (50 kHz) was performed for impedance and phase angle. Predictive equations estimated fat-free mass and percentage body fat. The bioimpedance index was calculated as stature²/impedance. Musculoskeletal fitness was assessed by handgrip strength, standing broad jump, squat jump, and countermovement jump.

RESULTS

In both sexes, health-related fitness had stronger associations with body composition than stature or weight. Handgrip strength was related to fat-free mass and bioimpedance index, while an inverse association with percent body fat emerged for standing broad jump, squat jump and countermovement jump. Phase angle is directly correlated with handgrip strength, standing broad jump, squat jump, and countermovement jump. In multiple regression analysis phase angle was an independent predictor of all health-related fitness tests, along with fat-free mass (or bioimpedance index) for handgrip strength, and with sex and percent body fat for the three jump tests.

CONCLUSIONS

The present study provided consistent information on the relationships between body composition and health-related fitness in young adults. Phase angle emerged as a significant predictor of all health-related fitness measures and might be useful for a more consistent assessment of musculoskeletal fitness.

Physical Fitness Surveillance and Monitoring Systems Inventory for Children and Adolescents: A Scoping Review with a Global Perspective

Surveillance of health-related physical fitness can improve decision-making and intervention strategies promoting health for children and adolescents. However, no study has comprehensively analyzed surveillance/monitoring systems for physical fitness globally. This review sought to address this gap by identifying: (1) national-level surveillance/monitoring systems for physical fitness among children and adolescents globally, (2) the main barriers and challenges to implementing surveillance/monitoring systems, and (3) governmental actions related to existing surveillance/monitoring systems. We used a scoping review to search, obtain, group, summarize, and analyze available evidence. Our review involved three stages: (1) identification of surveillance systems through a systematic literature review, with complementary search of the grey literature (e.g., reference lists, Google Scholar, webpages, recommendations), (2) systematic consultation with relevant experts using a Delphi method to confirm/add systems and to gather and analyze information on the barriers and challenges to implementing systems, and (3) Web searches for public documents on government sites and surveillance/monitoring system pages, and direct internet searches to identify relevant governmental actions related to surveillance systems. A total of 15 fitness surveillance/monitoring systems met our inclusion criteria. Experts identified a lack of government support and funding, and the low priority of fitness on the public health agenda as the main barriers/challenges to implementation. Several governmental actions related to surveillance systems were identified, including policies, strategies, programs, and guidelines. We propose a Global Observatory of Physical Fitness to help address these issues.

Health-Related Physical Fitness Evaluation in HIV-Diagnosed Children and Adolescents: A Scoping Review

BACKGROUND

Health-related physical fitness has been widely used to investigate the adverse effects of HIV infection/ART in children and adolescents. However, methods/protocols and cut-points applied for investigating health-related physical fitness are not clear. The aim of this scoping review was to map the literature to identify gaps in knowledge regarding the methods/protocols and cut-points.

METHODS

A scoping review, following the Joana Briggs Institute (JBI) guidelines, was conducted through ten major databases. Search followed the PCC strategy to construct block of terms related to population (children and adolescents), concept (health-related physical fitness components) and context (HIV infection).

RESULTS

The search resulted in 7545 studies. After duplicate removal, titles and abstracts reading and full text assessment, 246 studies were included in the scoping review. Body composition was the most investigated component (n = 244), followed by muscular strength/endurance (n = 23), cardiorespiratory fitness (n = 15) and flexibility (n = 4). The World Health Organization growth curves, and nationals' surveys were the most reference values applied to classify body composition (n = 149), followed by internal cut-points (n = 30) and cut-points developed through small populations (n = 16). Cardiorespiratory fitness was classified through cut-points from three different assessment batteries, as well as cut-points developed through studies with small populations, muscular strength/endurance and flexibility were classified through the same cut-points from five different assessment batteries.

CONCLUSIONS

The research on muscular strength/endurance, cardiorespiratory fitness and flexibility has been scarcely explored. The lack of studies that investigated method usability as well as reference values was evidenced.

Adherence to the Mediterranean Diet and Its Influence on Anthropometric and Fitness Variables in High-Level Adolescent Athletes

The objectives of the present research were to analyze adherence to the Mediterranean diet (AMD), to observe which variables most affect AMD, and to analyze whether AMD affects physical fitness and anthropometric parameters in high-level adolescent athletes. A total of 96 adolescent athletes in the under-16, under-18, and under-20 categories selected by the Athletics Federation of the Region of Murcia, of whom 47 were male (age = 18.31 ± 2.31 years old) and 49 female (age = 17.27 ± 1.44 years old), participated in this study. They completed the KIDMED questionnaire to discover their AMD, as well as an anthropometric and physical condition assessment. Results: The findings show that 61.45% had an excellent degree of AMD, 31.25% a moderate one, and 7.30% a poor one. The parameters that most conditioned AMD were the consumption of fruit, vegetables, nuts, legumes, fish, breakfast cereals, and dairy products (p = 0.011-0.000). AMD did not show significant differences in anthropometric characteristics and physical fitness (p = 0.057-0.996). Conclusions: The majority of high-level adolescent athletes have a moderate or excellent AMD. The degree of AMD seems to have no influence on physical fitness and anthropometric parameters in this population.

Evaluation of physical fitness and health of young children aged between 3 and 6 based on cluster and factor analyses

BACKGROUND

As life improves and sedentary time increases, young children's physical fitness gradually declines.

METHODS

Multi-stage stratified whole cluster sampling was utilized to sample 5584 preschoolers. Young infants' morphology, function, and quality were revealed using cluster and factor analysis.

RESULTS

The cluster analysis separated 3-6-year-olds into two genders: 1,551 men in group A "high physical fitness" 1,499 men in group B "low physical fitness"; 1,213 women in group A and 1,321 women in group B. Young children's fitness was measured by standing long jump(1.00), weight(1.00), and height(1.00). A cluster analysis of 3-4-year-olds classified them into three groups: 272 "muscular strength," 75 "average physical fitness," and 250 "low agility." Young children's health depends on weight (1.00), height (0.57), and chest circumference (0.54). A cluster analysis of the 4-5-year-olds classified them into two groups: 1070 "balance" and 806 "muscular strength." Young children's health depends on weight (1.00), height (0.74), and chest circumference (0.71). A cluster analysis of the 5-6-year-olds divided them into three groups: 1762 "high physical fitness," 384 "obese," and 105 "low physical fitness." Young children's physical health depends on BMI (1.00), weight (1.00), and chest circumference (1.00). Factor analysis demonstrated that muscle strength, body shape, cardiovascular variables, and physical fitness composite components affected young children's health.

CONCLUSION

Women should focus on motor function and strength, while men on flexibility. Male group B "low physical fitness" should focus on strength, motor function, and balance, whereas male group A "high physical fitness" should focus on flexibility. Then, female group A "high physical fitness" should emphasize variety.2) For 3-4-year-olds, group A "muscular strength" should focus on flexibility, and group C "low agility" on motor function. 3) For 4-5-year-olds, group A "balanced" should focus on strength and motor function; 4) For 5-6-year-olds, group B "obese" should emphasize weight loss, and group C "low fitness" should emphasize strength, motor function, and flexibility; 5) Young children's physical fitness depends on muscle strength, body shape, cardiovascular factors, and physical fitness composite.

Bullying Victimization, Real and Perceived Physical Fitness, and Self-Perception Profiles in Middle-School Students with Overweight or Obesity

Bullying victimization has been associated with body weight and physical fitness. In order to compare the prevalence of victimization among adolescents with normal weight or overweight/obesity and to evaluate the association between real or perceived physical fitness and self-perception profiles, a sample of 128 middle-school youths (mean age: 12.2 ± 0.8 years, 61% males) was recruited. The body mass index (BMI) Z score was calculated. Physical fitness was assessed by hand grip strength (HGS), long jump (LJ), and a 3 min step test (3MST). Perceived physical fitness, self-perception profiles (social competence, athletic competence, and physical appearance), and experiences of victimization (teasing about physical appearance, verbal offenses, and exclusion from group activities) were explored using validated questionnaires. Eighty youths (62.5%) showed overweight/obesity. Compared to their counterparts, normal-weight subjects showed lower HGS and perceived muscular strength; higher LJ and 3MST performance; higher perceived overall fitness, speed and flexibility, and physical appearance. Teasing and verbal offences were more frequent among students with overweight/obesity. Being teased about physical aspects was positively related with the BMI Z score. Exclusion from groups was positively associated with LJ performance. All the types of victimization investigated were inversely related to perceived social competence. These findings suggest that self-perception may protect one from victimization, regardless of nutritional status.

Association of liver function with health-related physical fitness: a cross-sectional study

BACKGROUND

In this study, by analyzing the correlation between various components of health-related physical fitness (HPF) and liver function indicators, the indicators of physical fitness that were highly correlated with liver function and could be monitored at home were screened to prevent more serious liver disease in the future, and to provide experimental basis for prescribing personalized exercise.

METHODS

A total of 330 faculties (female = 198) of a university were recruited. The indicators of HPF and liver function were measured. Spearman correlation analysis, multivariate linear regression, and cross-lagged panel model was used to data statistics.

RESULTS

In males, body fat (BF) was positively correlated with alanine aminotransferase (ALT); vital capacity and the vital capacity index were positively correlated with albumin; and vertical jump was positively correlated with globulin and negatively correlated with the albumin-globulin ratio (P < 0.05). However, there was no significant correlation among all indicators controlled confounding factors. In females, BF was negatively correlated with direct bilirubin; VO2max was positively correlated with indirect bilirubin; and vertical jump was positively correlated with the albumin-globulin ratio and significantly negatively correlated with globulin (P < 0.05). Controlled confounding factors, body fat percentage was positively correlated with globulin (β = 0.174) and negatively correlated with direct bilirubin (β = -0.431), and VO2max was positively correlated with indirect bilirubin (β = 0.238, P < 0.05). Cross-lagged panel analysis showed that BF percentage can negatively predict direct bilirubin levels with great significance (β = -0.055, P < 0.05).

CONCLUSIONS

HPF may play a crucial role in liver function screening, particularly for female faculty members. For males, BF, vertical jump, vital capacity and vital capacity index could be associated with liver function but are susceptible to complex factors such as age, smoking, diabetes, and hypertension. In females, BF percentage is an important predictor of abnormal liver function in addition to VO2max and vertical jump, which are not affected by complex factors.

Physical fitness trend after COVID-19 restrictions in Italian school-aged children: a cross-sectional study

BACKGROUND

Physical fitness (PF) is a marker of health in children. Muscular strength and speed-agility PF components play a crucial role in musculoskeletal development and bone health. The outbreaks of COVID-19 pandemic changed the daily and sports activities in younger increasing sedentary habits with a detrimental effect on PF. We aimed to investigate the impact of COVID-19 restrictions on PF in Italian school-aged children.

METHODS

We recruited 286 elementary school children, and they were tested through an internationally validated battery test, which evaluate muscular strength and speed-agility (as a multifactorial performance) prior (2018) and after the outbreak of COVID-19 pandemic (2021).

RESULTS

Our results showed a reduction in the lower limb strength (SBJ in boys mean difference (MD) -0.42 m; SBJ in girls MD=-0.20 m; P<0.05) and in the speed-agility ability (10x5 m in boys MD=14.1 s; 10x5 m in girls MD=11.2 s; P<0.05), while the upper limb strength remained steady before and after the restrictions. Specifically, for boys of all ages there was a reduction in lower limb strength and in speed-agility but not in upper limb strength. For girls of all ages there was not a recurrent trend, while for 6-8 girls there was a reduction only speed-agility, for 9-11 girls there was a reduction in lower limb and speed-agility.

CONCLUSIONS

Our results could be useful to help teachers and sport specialists to evaluate and improve strength and speed-agility in children. We encourage trainers and sport specialists to implement programs to help children to become more active and healthier during their lifespan.

Assessment of physical activity among adolescents: a guide to the literature

Purpose

The aim of this article is to systematically review articles and annual reports concerning young peoples' physical activity (PA) and linking this to considerations of the state and national defense.

Method

A systematic search of the literature included an analysis of publications accessible in global databases and other available books, student papers, and projects. The articles and reports were categorized based on year of publication, methods used, age of respondents, sample size, country, and digital object identifier (DOI).

Results

The result of this search is an overview of the extent and manner in which the worldwide scientific community is addressing the current situation and the long-term development of the physical fitness of adolescents. This publication also maps to what extent professional publications and articles are addressing PA from the perspective of the needs of armies and armed forces of various countries around the world.

Conclusions

The article provides a systematic overview of methods used to measure PA, and an overview of articles dealing with assessing PA. The examined articles indicate that from the perspective of not only national defense, but also health and overall quality of life, in particular, we need initiatives to encourage and motivate young people to increase their everyday PA. The research therefore also includes an overview of factors that may considerably influence PA. The results ascertained in this publication will be used, i.a. for investigating a longitudinal defense research project of the Ministry of Defense of the Czech Republic in which the authors are participating.

Bioelectrical Impedance Analysis-Derived Phase Angle and Body Composition Are Predictors of Health-Related Fitness in Children and Adolescents with Obesity

There is little evidence in children and adolescents with obesity of the relationships between muscle strength/cardiorespiratory fitness (both components of health-related fitness = HRF) and body composition. Body composition and HRF were studied in 281 children and adolescents with obesity to explore their mutual relationship and to identify the predictors of HRF. By performing a bioelectrical impedance analysis (BIA), the fat-free mass (FFM) and percentage of body fat (%BF) were calculated, and the phase angle (PhA) was recorded. Handgrip strength (HGS), the standard broad jump (SBJ), and five broad jumps (FIVEBJ) were considered for the assessment of muscle strength, and the six-minute walking distance (SIXMWD) for cardiorespiratory fitness. The BMI Z-score was slightly higher in boys, and the %BF was higher in girls, with no difference in the FFM. HGS, the SBJ, and FIVEBJ were greater in the male sex. After controlling for sex, HGS was associated with the FFM, and with height, weight, and absolute BMI. On the contrary, the SBJ and FIVEBJ were negatively associated with adiposity, with a weak relationship with the FFM. The SIXMWD was only poorly related to height, the BMI Z-score, and the waist-to-height ratio. These results were confirmed with a multiple regression analysis. HGS, the SBJ, and FIVEBJ were higher in the first compared to the third tertile of the PhA in both sexes. The PhA also remained a consistent predictor of HGS, the SBJ, and FIVEBJ in a multiple regression analysis. In conclusion, the following predictors have been identified for HRF: the FFM for the isometric strength of the upper limbs and adiposity indicators for the SBJ and FIVEBJ. The PhA emerged as a proxy index of muscle strength.

The effect of Baduanjin exercise on health-related physical fitness of college students: A randomized controlled trial

Background

The continuous decline in the physical fitness of college students has become a serious social problem worldwide. Therefore, it is necessary to explore the effective method improving college students' physique. Previous studies have shown that Baduanjin exercise is beneficial in improving sleeping quality, mental health, body flexibility, and body physique. However, the evidence is unclear whether Baduanjin exercise can be recommended as an effective exercise to promote health-related physical fitness of college students.

Methods

A total of 130 college students were recruited and randomly allocated to either the Baduanjin training or the control group at a ratio of 1:1. The students in the Baduanjin training group received a 12-week supervised Baduanjin exercise training intervention with a frequency of 1 h each day and 4 days per week, while those in the control group did not receive any specific exercise intervention and were informed to maintain their original lifestyle for 12 weeks. The outcomes of health-related physical fitness involving measurements of body flexibility, muscular strength, cardiopulmonary fitness, and body endurance were measured at baseline and after the 12-week intervention period. Mixed linear model was used to analyze the effect of the Baduanjin exercise intervention.

Results

Mixed linear model analyses showed that the Baduanjin training group had a significant increase in the composite scores of health-related physical fitness compared to the control group from baseline to 12-week post-intervention with a medium effect size (d = 0.68, P = 0.006). Moreover, there were significant improvements in vital capacity, physical flexibility, 800/1,000 m endurance running, and body composition (measured by body mass index (BMI), fat mass and body fat ratio) at end of 12-week intervention in the Baduanjin training group. No adverse events were observed in this trial.

Conclusion

Regular Baduanjin training may be an effective, safe exercise form to promote the health-related physical fitness of young adults.

Trial registration

Chinese Clinical Trial Registry, ChiCTR-IOR-17013011. http://www.chictr.ogr.cn.

Relationship between Specific Field-Based Physical Fitness Test Results and Selected Health Biomarkers in College-Aged Males: A Cross-Sectional Study

OBJECTIVE

This study aimed to verify the association between specific field-based physical fitness test results and selected health biomarkers in college-aged males.

METHOD

A total of 390 males participated in this research. The association between fitness test scores and anthropometric and health variables were examined. The fitness tests conducted were: Sit-and-reach test (S&R), standing long jump test (SLJ), Shuttle run test (SHR), and 20 m Multistage Fitness Test (BT) to estimate the maximum oxygen uptake (VO2max). The anthropometric and health variables assessed were: Weight (WE), height (HE), body mass index (BMI), body fat percentage (FAT), lean body mass (LBM), abdominal Girth (AG), waist-to-hip ratio (WHR), systolic blood pressure (SBP), diastolic blood pressure (DBP), oxygen saturation (SPO2), average blood pressure (A-BP), double product (DP), and fasting blood glucose (GLU).

RESULTS

S&R presented a weak significant correlation with SLJ, VO2max, and AG. SLJ maintained weak to moderate significant correlations with S&R, SHR, VO2max, HE, WE, LBM, WHR, BMI, FAT, AG, SBP, DBP, A-BP, DP, and GLU. SHR presented weak to moderate significant correlations with SLJ, VO2max, WE, BMI, AG, FAT, HE, SBP, DP, and GLU. VO2max maintained weak to moderate correlations with S&R, SLJ, SHR, WE, BMI, FAT, LBM, AG, and DP. Weak to moderate correlations were found between anthropometric and health variables, whereas the anthropometric variables presented significant correlations with each other, ranging from weak to very strong. Fitness test results presented weak to moderate correlations among themselves.

CONCLUSION

SLJ and SHR present weak to moderate validity to predict the selected anthropometric markers and weak to predict the selected health indicators except for SPO2. VO2max has only weak validity to predict the selected anthropometric markers, whereas S&R is not valid to predict the selected health or anthropometric markers. Anthropometric measurements have weak validity in predicting the selected health markers. BMI and AG are valid, simple, and economical measurements to assess body fat. A positive interaction between the results obtained in the field-based fitness tests conducted was observed.

School-Based Comprehensive Strength Training Interventions to Improve Muscular Fitness and Perceived Physical Competence in Chinese Male Adolescents

Purpose. This research was to see how effective and feasible school-based comprehensive strength training programs are in improving muscular fitness and perceived physical competence in Chinese male adolescents. Methods. A total of 123 participants ( $13.46\pm 0.60$ years) were randomized to comprehensive strength training intervention group (CST) ( $n=62$ ) and the control group (CON) ( $n=61$ ). The training sessions were performed three times a week for ten weeks in CST. Muscular fitness (i.e., muscular strength, power, and muscular endurance) and perceived physical competence were assessed at initial testing and final testing. Results.The subjects in the CST significantly improved their mean performance in standing long jump ( $p<0.05$ ), vertical jump ( $p<0.05$ ), 1 min push-ups ( $p<0.05$ ), 1 min sit-ups ( $p<0.05$ ), handgrip strength ( $p<0.05$ ), and perceived physical competence ( $p<0.05$ ) after the intervention. Moreover, the CST were greater in standing long jump ( $p<0.05$ ), vertical jump ( $p<0.05$ ), 1 min sit-ups ( $p<0.05$ ), handgrip strength ( $p<0.05$ ), and perceived physical competence ( $p<0.05$ ) compared to the CON, but no in 1 min push-ups ( $p>0.05$ ). Conclusions. The comprehensive strength training interventions designed in this study can significantly increase male adolescents’ muscular fitness, especially in the lower extremity muscle power and abdominal core endurance, and can enhance their perceived physical competence.

Perceived Difficulties in Physical Tasks and Physical Fitness in Treatment- and Non-Treatment-Seeking Youths with Obesity

Youths with obesity are more likely to experience physical and psychosocial distress which strongly limits physical activity, with consequences on the quality of life. Most evidence of lower physical fitness and physical activity levels has been reported in treatment-seeking samples, while few data are available in community samples. Our aim was to assess whether perceived difficulties in physical tasks and physical fitness performance differed between treatment- and non-treatment-seeking youths with obesity, enrolled from a hospital (H) and a school (S). Three hundred fifty-one youths (269 from H and 82 from S) were enrolled. Sports participation, sedentary habits and perceived difficulties in physical tasks were assessed by interview. Six-minute walk test (SMWD) and long jump (LJ) were performed. BMI Z-score, sedentary time and perceived difficulties were higher in H vs. S. In addition, youths from H scored worse in SMWD and LJ. For the same BMI Z-score, the perceived difficulties and physical fitness were poorer in the H compared to the S group. The setting (H) was the stronger predictor of perceived difficulties and lower performance. Our findings underline that physical aspects imposed by obesity are more evident in treatment-seeking youths. Counseling related to perceived difficulties in physical tasks and performance is useful to treat youth with obesity with appropriate and personalized modalities.

Physical, Psychological, and Body Composition Differences between Active and Sedentary Adolescents According to the "Fat but Fit" Paradigm

The practice of physical activity during adolescence is essential for the proper development of the population. In recent decades, the relevance of physical activity has been increasing, due to the development of the "fat but fit" paradigm. This paradigm shows that adolescents with a high level of physical fitness are healthier than adolescents with poorer physical fitness, regardless of their weight, giving importance to sports practice over other aspects. However, few previous studies have analyzed the differences in physical and body composition between active and sedentary adolescents in this paradigm. For this reason, the objectives of the present study were to establish the differences in body composition, physical performance, and adherence to the Mediterranean diet between active and sedentary adolescents; and to analyze the differences between active and sedentary adolescents according to the "fat but fit" paradigm. The sample consisted of 791 adolescent whose body composition, level of physical activity, adherence to the Mediterranean diet, and physical fitness were measured. It was found significant between active and sedentary adolescents in most of the anthropometric, AMD, and physical fitness variables, with a significant effect of the covariates gender, age, BMI, and biological maturation on the model. The binary logistic regression analysis performed shows that anthropometric variables, AMD, and VO2 max can be considered as primary outcomes to distinguish between active and sedentary groups of adolescents. Furthermore, the results showed that the active adolescents, regardless of their weight status, had lower fat mass and greater muscle mass, as well as a higher performance in the physical fitness tests, and greater adherence to the Mediterranean diet than the sedentary adolescents. To conclude, the practice of physical activity is a determinant for the improvement of body composition, physical performance, and adherence to the Mediterranean diet of the adolescent population, regardless of their gender, age, weight, or maturity status.

Reliability of International Fitness Scale (IFIS) in Chinese Children and Adolescents

Background and Objectives: It has previously been shown that the International Fitness Scale (IFIS) is a reliable and valid instrument when used in numerous regions and subgroups, but it remains to be determined whether the IFIS is a reliable instrument for use with Chinese children and adolescents. If the reliability of the IFIS can be verified, populational surveillance and monitoring of physical fitness (PF) can easily be conducted. This study aimed to test the reliability of the IFIS when used with Chinese children and adolescents. Methods: The convenience sampling method was used to recruit study participants. In total, 974 school-aged children and adolescents between 11 and 17 years of age were recruited from three cities in Southeast China: Shanghai, Nanjing and Wuxi. The study participants self-reported demographic data, including age (in years) and sex (boy or girl). The participants completed the questionnaire twice within a two-week interval. Results: A response rate of 95.9% resulted in a sample of 934 participants (13.7 ± 1.5 years, 47.4% girls) with valid data. On average, the participants were 13.7 ± 1.5 years of age. The test–retest weighted kappa coefficients for overall fitness, cardiorespiratory fitness, muscle fitness, speed and agility and flexibility were 0.52 (Std. errs. = 0.02), 0.51 (Std. errs. = 0.02), 0.60 (Std. errs. = 0.02), 0.55 (Std. errs. = 0.02) and 0.55 (Std. errs. = 0.02), respectively. Conclusions: The International Fitness Scale was found to have moderate reliability in the assessment of (self-reported) physical fitness in Chinese children and adolescents. In the future, the validity of the IFIS should be urgently tested in Chinese subgroup populations.

Development and Cross-Validation of a Predictive Equation for Fat-Free Mass in Brazilian Adolescents by Bioelectrical Impedance

The bioelectrical impedance analysis (BIA) is one of the most commonly used techniques for assessing body composition in a clinical setting and in field approaches, as it has the advantages of easy application, fast, and non-invasive, in addition to its relatively low cost. However, the available predictive equations need to be valid for the evaluated subjects. The aim of this study was to verify the validity of several published BIA equations in estimating fat-free mass (FFM) among Brazilian adolescents, in addition to developing and cross-validating a BIA equation to estimate FFM appropriate for Brazilian adolescents. This is a cross-sectional study with 257 adolescents (128 girls) aged 10-19 years, randomly divided into two groups, namely, development (n = 172) and cross-validation (n = 85). The standard technique for assessing FFM was dual X-ray absorptiometry (DXA). The paired t-test, multiple regression, and the Bland-Altman plots were used to test the validity of the proposed models and to perform cross-validation of the model. The equation derived in this study was as follows: FFM = -17.189 + 0.498 (Height²/Resistance) + 0.226 Weight + 0.071 Reactance - 2.378 Sex + 0.097 Height + 0.222 Age; r ² = 0.92; standard error of the estimate = 2.49 kg; the new equation for FFM showed better agreement when compared with that of the equations developed in other countries. In conclusion, the newly developed equations provide a valid FFM estimation and are recommended for Brazilian adolescents with similar characteristics.

Flexibility of Brazilian children and adolescents: a systematic review of the literature

abstract Flexibility is related to specific tissue properties of the body, which aim to determine the maximum range of motion of the joints without injury. This study aimed to identify and summarize the evidence on prevalence of adequate levels of flexibility in Brazilian children and adolescents (6 to 19 years old). We performed a systematic search of studies published from 2009 to 2019 in six databases (MEDLINE/PubMed; Scopus; SportDiscus; LILACS; Web of Science; SCIELO). Fourteen studies that compiled data from 11,666 participants in seven different Brazilian states were included. All studies conducted sit and reach tests to assess flexibility. Among all the children and adolescents in the analyzed studies, 58.9% of the total (62.0% of boys and 50.9% of girls) had adequate flexibility. We conclude that more than half of Brazilian children and adolescents have adequate flexibility for health.

Field-based physical fitness assessment in preschool children: A scoping review

Physical fitness, which can be measured using various health- and skill-related components, is an important indicator of child development and health status. This study undertakes a scoping review on physical fitness assessment methods in preschool children to summarize the most widely used field-based physical fitness batteries and specific test items for preschool children. A search of the literature in English was undertaken using two major electronics databases, which yielded 76 literatures that met the inclusion and exclusion criteria. These literatures took the quantitative indicators of physical fitness as the outcome variables in 3-6-year-old children. This review found that of these 76 literatures analyzed, 71.1% came from Europe and 89.5% were published after 2010. The results showed six physical fitness test batteries, with the assessing FITness in PREschoolers (PREFIT) battery is the most widely used, and specific test items such as body mass index (BMI), standing long jump, handgrip, one-leg stance, sit and reach, 20 m shuttle run test (SRT)-PREFIT, and 4 × 10 m SRT are widely used in corresponding components. Therefore, we recommend that an international standard for some specific test items should be developed for preschool children to facilitate more widespread adoption and promote physical fitness assessment for preschool children.

Gender Difference in Architectural and Mechanical Properties of Medial Gastrocnemius-Achilles Tendon Unit In Vivo

This study aims to explore whether gender differences exist in the architectural and mechanical properties of the medial gastrocnemius–Achilles tendon unit (gMTU) in vivo. Thirty-six healthy male and female adults without training experience and regular exercise habits were recruited. The architectural and mechanical properties of the gMTU were measured via an ultrasonography system and MyotonPRO, respectively. Independent t-tests were utilized to quantify the gender difference in the architectural and mechanical properties of the gMTU. In terms of architectural properties, the medial gastrocnemius (MG)’s pennation angle and thickness were greater in males than in females, whereas no substantial gender difference was observed in the MG’s fascicle length; the males possessed Achilles tendons (ATs) with a longer length and a greater cross-sectional area than females. In terms of mechanical properties, the MG’s vertical stiffness was lower and the MG’s logarithmic decrement was greater in females than in males. Both genders had no remarkable difference in the AT’s vertical stiffness and logarithmic decrement. Gender differences of individuals without training experience and regular exercise habits exist in the architectural and mechanical properties of the gMTU in vivo. The MG’s force-producing capacities, ankle torque, mechanical efficiency and peak power were higher in males than in females. The load-resisting capacities of AT were greater and the MG strain was lesser in males than in females. These findings suggest that males have better physical fitness, speed and performance in power-based sports events than females from the perspective of morphology and biomechanics.