BackgroundHand grip strength (HGS) is associated with a number of causes resulting in cardiovascular death, in addition to bone fragility, and the presence of sarcopenia. The goal of our study was to analyze HGS of students based on chronological and biological age and propose normative standards for children and adolescents from Chile.MethodsWe studied 4604 school children of both sexes between the ages of 6.0 and 17.9 years of age. Weight, standing height, sitting height, and hand grip strength (HGS- right and left) were measured. The Body Mass Index (BMI) was calculated, and the biological age was calculated by using age at peak height velocity (APHV).ResultsWhen arranged by chronological age, no significant differences occurred in HGS between both sexes of school children from age 6 to 12 years of age. However, from ages 13 to 17, males showed greater HGS than females. Significant differences also emerged between both sexes and at all levels for biological age (APHV). For males, chronological age explained the HGS occurring between 0.74 to 0.75% and for females between 0.54 to 0.59%. For males, biological age explained the HGS for the range of 0.79 to 0.80% and 0.62 to 0.67% for females. The normative data for HGS for both sexes is expressed in percentiles.ConclusionsHGS during childhood and adolescence needs be analyzed and interpreted in terms of biological age rather than chronological age. The normative data to evaluate the HGS are a tool that can help professionals working in clinical and epidemiological contexts.

Relationships between the body mass index and physical fitness were generally nonlinear (parabolic) in youth 10-17 years.

The objective of this study was to analyze the influence of parents and Physical Education teachers on adolescent's extracurricular Physical Activity. Data were obtained from the Chilean System for the Assessment of Educational Quality test with a large representative sample of 23,180 students (11,927 females and 11,253 males aged 13.7 and 13.8 years respectively). The analyzed variables were the extracurricular physical activity of adolescents, parents’ and physical education teachers’ encouragement to do physical activity and parents’ physical activity behavior. Associations between variables were analyzed using chi-squared tests. Two logistic regression models, one adjusted and the other unadjusted, were performed for each physical activity variable (vigorous, moderate, mild and total) in order to obtain odds ratios from parents’ and physical education teachers’ influence variables. Results showed that parents’ influence is more relevant than physical education teachers’ influence in order to promote physical activity in adolescents, regardless of age, sex and physical condition.

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BackgroundThe importance of assessing body fat variables and physical fitness tests plays an important role in monitoring the level of activity and physical fitness of the general population. The objective of this study was to develop reference norms to evaluate the physical fitness aptitudes of children and adolescents based on age and sex from the lake region of Itaipú, Brazil.MethodsA descriptive cross-sectional study was carried out with 5,962 students (2,938 males and 3,024 females) with an age range of 6.0 and 17.9 years. Weight (kg), height (cm), and triceps (mm), and sub-scapular skinfolds (mm) were measured. Body Mass Index (BMI kg/m2) was calculated. To evaluate the four physical fitness aptitude dimensions (morphological, muscular strength, flexibility, and cardio-respiratory), the following physical education tests were given to the students: sit-and-reach (cm), push-ups (rep), standing long jump (cm), and 20-m shuttle run (m).Results and DiscussionFemales showed greater flexibility in the sit-and-reach test and greater body fat than the males. No differences were found in BMI. Percentiles were created for the four components for the physical fitness aptitudes, BMI, and skinfolds by using the LMS method based on age and sex. The proposed reference values may be used for detecting talents and promoting health in children and adolescents.

Objectives: Physical growth and body adiposity patterns provide relevant information to infer the nutritional and health status of students. Our objectives were (a) to compare the variables of body adiposity and physical growth of Chilean children and adolescents with data from the CDC-2012 and international studies, and (b) to develop regional reference curves to evaluate growth and body adiposity. Methods: 8,261 children and adolescents were studied. We evaluated the weight, height, and waist circumference (WC). The Body Mass Index (BMI) was calculated. Their physical growth and body adiposity were compared with the CDC-2012 references as well as with other international references. Percentile curves for weight, height, BMI, and WC were constructed with the LMS method. Results: The Chilean students showed reduced weight and height during adolescence when compared with the CDC-2012 reference. During early ages, the BMI for the Chilean sample was lower while at advanced ages, the WC values were greater in comparison to the CDC-2012 reference. Graphic comparisons with international studies indicated that Chilean students weighed more at all ages. However, height was slightly greater until age 14 for males and age 11 for females. Body adiposity (BMI and WC) for the Chilean students was slightly higher at early ages while at later ages, adiposity values were relatively similar for both sexes. Conclusions: Discrepancies were observed between the physical growth and body adiposity trajectories and the American CDC-2012 references and the international studies. The proposed percentiles for weight, height, BMI, and WC for each age and sex may be useful for health sciences professionals and researchers.

BackgroundThe Dual Energy X-Ray Absorptiometry (DXA) is the gold standard for measuring BMD and bone mineral content (BMC). In general, DXA is ideal for pediatric use. However, the development of specific standards for particular geographic regions limits its use and application for certain socio-cultural contexts. Additionally, the anthropometry may be a low cost and easy to use alternative method in epidemiological contexts. The goal of our study was to develop regression equations for predicting bone health of children and adolescents based on anthropometric indicators to propose reference values based on age and sex.Methods3020 students (1567 males and 1453 females) ranging in ages 4.0 to 18.9 were studied from the Maule Region (Chile). Anthropometric variables evaluated included: weight, standing height, sitting height, forearm length, and femur diameter. A total body scan (without the head) was conducted by means of the Dual Energy X-Ray Absorptiometry. Bone mineral density (BMD) and the bone mineral content (BMC) were also determined. Calcium consumption was controlled for by recording the intake of the three last days prior to the evaluation. Body Mass Index (BMI) was calculated, and somatic maturation was determined by using the years of peak growth rate (APHV).ResultsFour regression models were generated to calculate bone health: for males BMD = (R2 = 0.79) and BMC = (R2 = 0.84) and for the females BMD = (R2 = 0.76) and BMC = (R2 = 0.83). Percentiles were developed by using the LMS method (p3, p5, p15, p25, p50, p75, p85, p95 and p97).ConclusionsRegression equations and reference curves were developed to assess the bone health of Chilean children and adolescents. These instruments help identify children with potential underlying problems in bone mineralization during the growth stage and biological maturation.

BackgroundMaintaining and building healthy bones during the lifetime requires a complicated interaction between a number of physiological and lifestyle factors. Our goal of this study was to analyze the association between hand grip strength and the maximum peak expiratory flow with bone mineral density and content in adolescent students.MethodsThe research team studied 1427 adolescent students of both sexes (750 males and 677 females) between the ages of 11.0 and 18.9 years in the Maule Region of Talca (Chile). Weight, standing height, sitting height, hand grip strength (HGS), and maximum peak expiratory flow (PEF) were measured. Furthermore, bone mineral density (BMD) and total body bone mineral content (BMC) were determined by using the Dual-Energy X-Ray Absorptiometry (DXA). Hand grip strength and PEF were categorized in tertiles (lowest, middle, and highest). Linear regression was performed in steps to analyze the relationship between the variables. Differences between categories were determined through ANOVA.ResultsIn males, the hand grip strength explained 18–19% of the BMD and 20–23% of the BMC. For the females, the percentage of variation occurred between 12 and 13% of the BMD and 17–18% of the BMC. The variation of PEF for the males was observed as 33% of the BMD and 36% of the BMC. For the females, both the BMD and BMC showed a variation of 19%. The HGS and PEF were divided into three categories (lowest, middle, and highest). In both cases, significant differences occurred in bone density health between the three categories.ConclusionsIn conclusion, the HGS and the PEF related positively to the bone density health of both sexes of adolescent students. The adolescents with poor values for hand grip strength and expiratory flow showed reduced values of BMD and BMC for the total body. Furthermore, the PEF had a greater influence on bone density health with respect to the HGS of the adolescents of both sexes.