Fitness In Boys Research Articles

Associations Between Substitution of Sedentary Behavior Patterns With Physical Activity and Cardiovascular Risk Factors in Adolescents: A 3-Year Longitudinal Study.

Little is known on how the substitution of time spent in sedentary behavior (SB) patterns with time spent in physical activity impacts cardiovascular risk factors during adolescence. The study aimed to investigate how the substitution of time spent in SB and sedentary bouts with time spent in different physical activity intensities was associated with longitudinal changes in cardiovascular risk factors in analyses stratified by sex. This is a prospective cohort study with a mean follow-up period of 3.2 (±0.34) years, involving 109 (60 girls and 49 boys) Brazilian adolescents. Body mass index, waist circumference, and cardiorespiratory fitness were the cardiovascular risk factors considered. A cardiovascular risk score was calculated. Sedentary bouts, light physical activity (LPA), and moderate to vigorous physical activity (MVPA) were measured by accelerometers. Multivariate linear regression models adopting the isotemporal substitution were used to analyze the association between substitution of 10minutes per day of sedentary bouts with LPA and MVPA and risk factors. All analyses considered 5% significance levels. Substitutions of SB, short and long bouts, with MVPA were associated with higher cardiorespiratory fitness in boys (β = 0.077; 95% confidence interval, 0.001 to 0.55; β = 0.076; 95% confidence interval, 0.003 to 0.154; and β = 0.084; 95% confidence interval, 0.001 to 0.167, respectively). No associations were observed when analyses involved substitution of sedentary bouts with LPA, adiposity, cardiovascular risk score, and girls. Substituting SB bouts with MVPA appears to favorably influence changes of cardiorespiratory fitness in boys during adolescence. Greater benefits appear to occur when longer sedentary bouts are substituted by MVPA.

Associations between Dietary Patterns and Physical Activity with Physical Fitness among Adolescents in Shandong Province, China: A Cross-Sectional Study

The trend of physical fitness (PF) and physical activity (PA) among Chinese adolescents is not optimistic, and unhealthy dietary behaviors are common. PA and dietary patterns (DPs) have been linked to PF in adolescents, but the associations between DPs and PF with PF in Chinese adolescents are rarely discussed. A total of 8796 adolescents aged 11-18 were enrolled from Shandong Province, China. The CNSPFS battery was applied to assess PF. PA levels and diet quality were determined using the Physical Activity Questionnaire for Adolescents and the modified Chinese Diet Quality Questionnaire, respectively. This study used factor analysis to identify DPs and linear regression models to investigate the association between PF and related factors. The average PF score of the participants was 75.67. Adolescents who were girls, lived in rural areas and were active in PA performed better on the PF test (p < 0.05). Boys whose fathers were university educated or above had a higher probability of achieving higher PF scores (OR 4.36, 95% CI 1.32-14.36); however, if their mothers were university educated or above, they had a lower probability of achieving higher PF scores (OR 0.22, 95% CI 0.063-0.76). Unhealthy dietary pattern was negatively correlated with cardiorespiratory fitness in boys (OR 0.56, 95% CI 0.31-0.98). The association between unhealthy dietary pattern and girls' BMI became significant after adjustment for PA (p < 0.05). Girls performed better in PF than boys. Highly educated fathers could contribute to improve the PF performance in boys. There were four DPs among adolescents in Shandong Province, and different DPs may have different effects on PF in boys and girls.

Physiological Variables that Contribute to Aerobic Fitness in Boys during Early Adolescence in the Context of Basketball Training and the Maturity Level.

The aim of this study was to assess physiological variables that contribute to aerobic fitness in respect to basketball training and the maturity level in adolescent boys. Our subjects were 28 basketball-trained and 22 control-group boys (average age: 11.83 ± 0.43 years). An incremental treadmill running test to exhaustion was performed twice with a 1-year interval between the sessions to determine the following peak aerobic fitness variables: oxygen uptake, stroke volume, cardiac output, minute ventilation, and others. Maturity offset was used to evaluate the maturity level. The basketball-trained group exhibited a higher peak ratio-scaled oxygen uptake (1st session: 50.55 ± 6.21 and 46.57 ± 5.68 ml/kg/min in basketball and control-group boys, respectively, p = 0.024; 2nd session: 54.50 ± 6.50 and 45.33 ± 5.99 ml/kg/min, respectively, p < 0.001) during both testing sessions. During the 2nd session, the basketball-trained group also showed a significantly higher peak arteriovenous oxygen difference (basketball-trained boys: 14.02 ± 2.17 ml/100 ml; control-group boys: 12.52 ± 2.49 ml/100 ml; p = 0.027) and peak minute ventilation (basketball-trained boys: 96.08 ± 21.71 l/min; control-group boys: 83.14 ± 17.85 l/min; p = 0.028). The maturity level among the basketball-trained boys was correlated with peak variables: oxygen uptake, stroke volume, cardiac output, and minute ventilation, but not with the ratio-scaled oxygen uptake. In conclusion, basketball training at a young age among boys improved aerobic fitness compared with sedentary boys. More mature basketball players were not superior to their less mature peers regarding aerobic fitness after adjusting for body dimensions.

Inequalities in the association between adherence to the Mediterranean diet and physical fitness in the young population during the COVID-19 lockdown.

Objective: this study analyzed the association between adherence to the Mediterranean diet and proxy-reported physical fitness among Spanish and Brazilian youths during the COVID-19 lockdown according to several inequality indicators. Methods: we conducted a cross-sectional study with parents and guardians of children and adolescents from Spain and Brazil. The evaluation process was through the use of online questionnaires. Adherence to the Mediterranean diet was assessed using the Mediterranean Diet Quality Index in Children and Adolescents. Proxy-reported physical fitness was determined using the International Fitness Scale. Inequality indicators (gender, nationality, socioeconomic status, and parents/guardians' education level) were evaluated with a survey completed by the participants' parents/guardians. Binary logistic regression models estimated the association between adherence to the Mediterranean diet and proxy-reported physical fitness, with stratification according to inequality variables. A total sample of 1,099 Spanish and Brazilian individuals (47.6% girls, aged 3 to 17 years) were included in the analysis. Results: compared to the "improvement needed to Mediterranean diet" category, the "optimal Mediterranean diet" group was significantly associated with "very good" physical fitness in boys (OR = 1.5; 95 % CI: 1.0-2.1) and in participants with parents/legal guardians' education level without university studies (OR = 1.5; 95 % CI: 1.0-2.4). Conclusions: gender and parents/guardians' education level plays a significant role in the association between the "optimal Mediterranean Diet" and "very good" physical fitness level in Spanish and Brazilian children and adolescents. Future prospective studies are needed to investigate the role of inequality indicators in this relationship.

Physical fitness in children and adolescents categorized by fat mass level

To evaluate the relationship between fat mass with anthropome tric indicators and, secondly, to compare the performance of physical fitness among children and adolescents categorized with adequate and excess fat mass. A descriptive cross-sectional study was conducted with 863 schoolchildren aged 6 to 17.9 years. Weight, height, and waist circumference were measured. physical fitness [speed (20m), agility (10x5m), and ho rizontal jump] was evaluated. Fat mass was calculated by anthropometric equation, body mass index, ponderal index, and waist to height ratio. Data were grouped into 6 age groups. Children of both sexes categorized as having adequate levels of fat mass had lower values of body mass index, ponderal index, and waist to height ratio than children with high levels of fat mass. In physical fitness, children with adequate fat mass were better than the ones with elevated fat mass. In girls with adequate fat mass, better results were observed in horizontal jump and agility during adolescence. There were no differences in the speed test. Fat mass can be considered as a valuable tool for determining excess body fat and categorizing children and adolescents with adequate and excess fat mass. In addition, having acceptable levels of fat mass may contribute to better physical fitness in boys in horizontal jump, agility, and speed and, in girls, only in horizontal jump and agility.

Physical Fitness in Preschool Children

Introduction. The level of mental and motor development as well as physical fitness and perceptual-motor performance should guarantee success in adapting to the new school environment.&#x0D; The aim of the research. The aim of the research was to determine physical fitness in preschool children of both genders aged from 4 to 7 years.&#x0D; Material and methods. The study included 275 children at the chronological age of 4 to 7 years including 134 girls and 141 boys. In order to assess physical fitness, the authors used the Wrocław Physical Fitness Test for preschool children completed by the endurance test&#x0D; Results. Final physical fitness results showed that six-year-old boys were the fittest and less fit were girls at the age of seven. The least fit were boys and girls at the age of four. &#x0D; Conclusions&#x0D; The Wrocław Physical Fitness Test and the endurance test revealed that the experimental group of children aged between four and seven years from the Western Pomerania region represented a satisfactory physical fitness level. It should be noted that this level was significantly lower than the ones obtained in tests conducted by other authors in 2006, 1996, 1972, and 1967.&#x0D; The represented fitness level, especially the level of endurance, may result in adaptation disorders during the school shock period.&#x0D; The phenomenon of sexual dimorphism at preschool age is demonstrated by significantly better physical fitness in boys at the age of five and six and balanced fitness at the age of seven.&#x0D; Positive development of physical fitness is not supported by ongoing lifestyle pre-orientation. It is recommended to complete primary school admission criteria for the first form by physical fitness standards, including endurance.

Low aerobic fitness among adolescents: prevalence and associated factors

It was our objective to estimate the prevalence and associated factors with low aerobic fitness among adolescents. A cross-sectional study was conducted with 575 subjects aged 11–17 years from Criciuma, SC, Brazil. The 9-minute walk/run test was used to assess aerobic fitness. Sociodemographic data and daily habits were collected using a self-administered questionnaire. Anthropometric evaluation was also performed to calculate anthropometric indicators of obesity. The Chi-square test and the binary logistic regression were used. The prevalence of low aerobic fitness in boys aged 11–13 years was 46.0% and in girls 40.5% (p<0.05), while in boys aged 14–17 years, the prevalence was 59.6% and in girls 46.6 % (p<0.05). Boys aged 11-13 (OR: 5.04; 95% CI: 1.93–13.17) and those aged 14–17 years (OR:3.78; 95% CI: 1.90–7.52) and girls aged 11-13 years (OR: 3.62; 95% CI: 1.24–10.52) from private schools were about four times more likely of having low aerobic fitness compared to those from public schools. Girls aged 11-13 years (OR: 2.40; 95% CI: 1.04–5.54) with inadequate sleep were more likely to have low aerobic fitness than those with adequate sleep. High prevalence of low aerobic fitness was associated with private schools and inadequate sleep in both sexes. KEYWORDS: cardiorespiratory fitness; students; adolescent health; running.

Profiling children longitudinally: A three-year follow-up study of perceived and actual motor competence and physical fitness.

Longitudinal designs enhance our understanding of children's development and its influence on movement behaviors and health. This three-year follow-up study aimed to develop profiles according to perceived and actual motor competence (MC) (locomotion, object control, and overall) and physical fitness in boys and girls longitudinally including children's temporal migrations among clusters in terms of profiling trends. A secondary aim was to compare physical activity participation and weight status at each time point according to these profiles. One hundred and four typically developing Spanish children (45.8% girls) between 4 and 9years old at baseline participated in this study. Data were collected at three time points one year apart, between January 2016 and May 2018. A self-organizing map and K-means cluster analysis were used to classify and visualize the values and temporal trajectories longitudinally. The study of the profiles in three consecutive years revealed five profiles, three for boys [ie, profile 1 (aligned-high), profile 2 (aligned-partially-low perception-medium actual MC and fitness), and profile 3 (non-aligned-medium perception-low actual MC and fitness)]; and two for girls [ie, profile 4 (aligned-high) and profile 5 (aligned-low)]. For highly perceived and capable children, boys (profile 1) and girls (profile 4), there was a tendency for higher physical activity participation and lower body mass index and waist circumference over time compared to their counterparts who had medium and/or low levels in perception and actual MC and fitness (P<.05). As children age, those with low values in perceived and actual MC and fitness in object control skills will present a higher probability of maintaining unhealthy lifestyles. So, prior intervention, children's profiles identification should be analyzed according to the type of MC.

Is children's health-related quality of life associated with physical fitness and mode of commuting? PREVIENE Project.

The aims of this study were (1) to examine the associations between self-reported health-related quality of life (HRQoL), health-related physical fitness (cardiorespiratory fitness, muscular strength, and speed-agility), and mode of commuting to and from school in Spanish children, and separately by gender and (2) to analyse the difference in cardiorespiratory fitness by mode of commuting to and from school by gender. We conducted a cross-sectional analysis that included 415 children aged 8.47 ± 0.36 years from 14 schools in Granada, Spain. The HRQoL outcome was assessed using the valid and reliable KINDL-R questionnaire, which covers six life dimensions, children's physical fitness was assessed using the ALPHA fitness test battery, and while commuting to and from school was assessed using the valid, reliable, and feasible 'Mode and Frequency of Commuting To and From School Questionnaire'. Cardiorespiratory fitness was positively correlated with all dimensions of HRQoL in boys, whereas higher muscular strength (standing long jump) was positively correlated with the emotional wellbeing dimension in girls. In addition, boys who actively commute to school (walking) presented better cardiorespiratory fitness. Moreover, children who actively commuted to school (walking) presented better scores for the emotional wellbeing, family, and school dimensions, as well as total scores (both, p < .05) of HRQoL. In our study, HRQoL was positively correlated with cardiorespiratory fitness in boys (all dimensions), whereas muscular strength (standing long jump) was positively correlated with the emotional wellbeing dimension only in girls. Active commuting to and from school was associated with higher levels of cardiorespiratory fitness, school dimension, and KINDL-R total score. Improving cardiorespiratory fitness might be especially useful to improve HRQoL in children, and vice versa.

The state of the cardiorespiratory system and the level of physical fitness at students of institutions of higher education of the I-II level of accreditation

The article provides the results of determining the state of the cardiorespiratory system and the level of physical fitness of the 1st year students of The Housing and Communal College.&#x0D; As a result of the conducted research, “below the average” level of functioning the cardiorespiratory system was defined at students. So, measures of the functional state of the respiratory system (Skibinski index) when compared with the assessment scale are equal to the score - 2 points, which corresponds to “below the average” level. Measures of the state of the cardiovascular system regulation (Robinson index) when compared with the scoring scale at students of both study groups are equal to the score - 3 points, which corresponds to the “average” level.&#x0D; The state of the cardiorespiratory system of boys is mainly higher than girls’ one in the sexual aspect. The exception is the results of measuring systolic blood pressure, where there is an opposite trend - the indicators of girls are higher than the results of boys. At the same time, the noted differences are valid only in indicators of the state of the respiratory system (p&lt;0,05; 0,001). The distinctions are unreliable (p&gt;0,05) in indicators of the cardiovascular system.&#x0D; The data of the conducted research indicates the “average” level of physical fitness at boys, which on average equals the “good” and “sufficient” levels at girls, which on average equals the score “satisfactory”. So, the boys have indicators for the development of all physical qualities that meet the assessment “good”. Speed, high-speed and power qualities and endurance meet the assessment “satisfactory”, strength and agility - the assessment “good” at girls.&#x0D; The physical fitness of boys is significantly higher than girls’ one in the sexual aspect (p&lt; 0,001). The exception is the development of flexibility, where the results of girls are higher than boys’ ones, but unreliably (p&gt;0,05).&#x0D; Thus, the results of the research indicate the feasibility of introducing the special physical exercises aimed at improving the functional state of the cardiorespiratory system and developing basic physical qualities into the physical education process of the 1st year students of institutions of higher education of the I-II level of accreditation.

Secular Trends of Physical Fitness in Twenty-Five Birth Cohorts of Slovenian Children: A Population-Based Study.

In Slovenia, the national SLOfit surveillance system of the somatic and motor development of children and youth has been enabling researchers to observe the developmental trends of the entire population of school-aged children since 1987. The national database currently incorporates over 7.2 million sets of measurements of eight fitness tests and three anthropometric measurements. Since 1991, as in the rest of the world, in Slovenia, there is a common perception that the physical fitness of contemporary children is in decline and below the level of the physical fitness of the previous generation's childhood fitness. Our paper examines the trends of physical fitness in 26 birth cohorts of 7–10-year-olds. The analysis shows that the secular trends of physical fitness in boys and especially in girls have been positive and that the level of physical fitness of recent birth cohorts exceeds the national average of physical fitness of the 1989–2019 period. At the same time, the analysis reveals that the distribution of physical fitness has been changing from almost normal in the cohorts born in the first half of the 1980s, toward positively skewed in the subsequent cohorts born before the year 2000, and bimodal distribution in the later cohorts, indicating growing inequality and polarization of the motor development of children.

The associations between digit ratio, aerobic fitness, physical skills, and overall physical fitness of elite youth distance runners

Lower digit ratios between the lengths of fingers 2 (2D) and 4 (4D) (2D:4D) are associated with superior distance running and athletic performance. We examined relationships between 2D:4D, aerobic fitness, physical skills, and overall physical fitness of elite adolescent boy and girl distance runners. Subjects were top five finishers for their sex and age in 10 or more races of 10 km or longer in Michigan in 1981. We calculated 2D:4D of 15 girls and 11 boys from radiographs. Subject peak O2 consumption (VO2Peak ), ventilatory threshold (VT), and point of equivalent change (PEC) were collected during intermittent treadmill protocol tests. Performances on physical skills tests (flex-arm hang, broad jump, vertical jump, figure-8-run, sit ups, and sit-and-reach test) were collected in the laboratory. We examined the interrelationships between 2D:4D, subject sex, aerobic fitness, physical skills test performance, and overall physical fitness, a composite of aerobic and physical skills performance with correlation, linear regression, t tests, and principle component analyses. Girls had significantly larger right hand (R) 2D:4D than boys. Boys had greater VO2Peak by mass than girls. Boys with lower R2D:4D had significantly greater VO2Peak and PEC. Girls with lower R2D:4D had significantly greater VT. Factors associated with aerobic fitness explained most of the variation in composite physical fitness scores. Composite aerobic fitness, physical skills, and overall physical fitness scores of boys were negatively correlated with R2D:4D. These data suggest that R2D:4D may help predict distance running performance in girls and boys and overall physical fitness in boys and provide additional insights into the innate factors influencing youth physical fitness.

Phase Angle is Determined by Body Composition and Cardiorespiratory Fitness in Adolescents.

The phase angle is used to evaluate nutritional status and is an indicator of cellular health. Cardiorespiratory fitness and body composition are strong indicators of health during adolescence. We aimed to evaluate if body composition and cardiorespiratory fitness have an association with phase angle among adolescents. 203 girls and 220 boys (12.8±1.3 years) were evaluated. Peak height velocity, percentage fat mass, fat-free mass, cardiorespiratory fitness, and phase angle measurements were collected. Linear regression adjusted by peak height velocity was used to verify if predictor variables were associated with phase angle among adolescents. Phase angle showed correlation with fat-free mass (girls: r=0.42 and boys: r=0.37); with percent fat mass (girls: r=0.23); and with cardiorespiratory fitness (boys: r=0.19). Linear regression showed that percentage fat mass (in girls) and cardiorespiratory fitness (in boys) had an effect of 11 and 17% in phase angle, respectively, while fat-free mass had an effect of 22 and 26% in phase angle for girls and boys, respectively. Changes in phase angle seem to be more associated with the percentage fat mass in girls, cardiorespiratory fitness in boys, and fat-free mass in both when controlled by peak height velocity.

Prediction of cardiorrespiratory fitness by screen time in schoolchildrens

The time spent in front of the screens, results in accumulations of sedentary behavior, which is related to health damages to adolescents, such as a low cardiorespiratory fitness. In this sense, this study aimed to predict cardiorespiratory fitness through screen time in schoolchildren. Cross-sectional study, as a sample composed of 2.764, of which 1.370 boys and 1.394 girls between 10 and 18 years old were the public school system of Paranavaí, Paraná, Brazil The self-report questionnaire was used to estimate screen time (ST) and cardiorespiratory fitness (CF) was estimated using the 20-meter multi-stage test, and to verify the predictive power of the screen time in relation to CF, the Roc curve was used. The results showed that screen time was considered a good predictor of cardiorespiratory fitness in boys (weekdays, weekends and all week), and in general (boys and girls) only for weekdays (Monday to Friday). In the survey, the screen time cut-off for boys on weekdays was 137 minutes (CI: 65-43), at weekends of 165 minutes (58-51) and general of 156 minutes (64-45). For the general sample (girls and boys), the cut bridge on weekdays was 142 minytes (64-44). For the girls the screen time had no predictive power (CI&gt; 0.50) and consequently the cut-off point was not verified. Thus, it can be concluded that the screen time in boys and in general (only weekdays) was able to predict cardiorespiratory fitness and that this variable of easy application can be an important tool to predict CF in the school environment.

Associations between Daily Step Counts and Physical Fitness in Preschool Children

Purpose: To investigate the relationships between daily step counts and physical fitness in preschool children. Methods: Preschoolers’ step counts were assessed by ActiGraph accelerometers consecutively for seven days. Physical fitness was assessed by a 20 m shuttle run test (cardiorespiratory fitness), the handgrip and standing long jump tests (musculoskeletal fitness), and the 2 × 10 m shuttle run test (speed/agility). A composite score was created from the mean of the standardized values of all physical fitness tests. Results: A total of 301 preschoolers (134 girls, mean age 57.40 ± 5.47 months; 167 boys, mean age 58.10 ± 5.34 months) were included in the final analysis. Compared with the lowest tertile, boys and girls in the highest tertile of step counts achieved high physical fitness with odds ratio (OR) being 5.39 (95% CI = 1.65–17.59) and 4.42 (95% CI = 1.30–14.99), respectively, after adjusting for confounders. Meanwhile, a relationship was observed for each 1000 steps/day increment being associated with 43% (OR = 1.43, 95% CI = 1.10–1.85) and 62% (OR = 1.62, 95% CI = 1.20–2.19) increment for high physical fitness in boys and girls, respectively. In addition, significant non-linear relationship was observed between daily steps and physical fitness in boys, which indicated that accumulated 8000 steps/day was associated with the highest ratio to achieve high physical fitness. Conclusions: Positive relationships between step counts and physical fitness were observed in preschool children, and the relationships were strongest for those who accumulated 8000 steps/day in boys. To confirm the findings in this study, well-designed and large-scale longitudinal studies are needed in the future.

Morphofunctional features and physical fitness of boys 6 - 9 years old under the influence of various physical activity

The aim of this research was to investigate morphofunctional features and physical fitness of boys 6 - 9 years old under the influence of various physical activity. The research performed in 2020 comprised 246 boys of 6 - 9 years old with different physical activity (121 children who are not involved in sports; 79 martial artists and 46 gymnasts with experience of 8 months and 4 years old). It was found that systematic sports activities of 6 - 9 years old boys have a positive effect on physical fitness and optimize morphofunctional indicators of physical development. The effect of the sport on the physical development and fitness of the boys depends on the start date and time of training sessions: a higher level of young gymnasts physical fitness is accompanied by a more intense adaptation of the cardiovascular system relative to martial artists. Differences in morphofunctional state and physical fitness between boys who are not involved in sports and young athletes are least significant in 6 year old boys, intensifying as growing up and increasing sport experience. It is more typical for gymnasts.

FEATURES OF PHYSICAL DEVELOPMENT AND PHYSICAL FITNESS IN BOYS WITH HEARING IMPAIRMENTS AND THEIR CORRECTION USING SPORTS GYMNASTICS

Aim. The article deals with a possible correction of physical development and physical fitness in boys with hearing impairments with the help of sports gymnastics. Materials and methods. Boys aged 7–9 years were divided into two groups – experimental and control – 25 persons in each group. In the control group, the lessons were conducted following a standard program. In the experimental group, the lessons followed the program of sports gymnastics. In both groups, the training course lasted six months. Testing was conducted at the beginning and the end of the study. Results. After the experiment, the results of the experimental group exceed those of the control group. Conclusion. Regular lessons made according to a sports gymnastics program allow improving physical development and physical fitness in boys with hearing impairments aged 7–9 years.

The 20 m shuttle run is not a valid test of cardiorespiratory fitness in boys aged 11–14 years

ObjectivesThe 20 m shuttle run test (20mSRT) is used to estimate cardiorespiratory fitness (CRF) through the prediction of peak oxygen uptake (V˙O2), but its validity as a measure of CRF...

Associations of accelerometer-measured sedentary time, sedentary bouts, and physical activity with adiposity and fitness in children

ABSTRACTSedentary time (ST) has been inconsistently associated with adiposity and cardiorespiratory fitness in children in previous studies. We studied cross-sectional associations of ST, light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA) with fat mass index (FMI) and cardiorespiratory fitness (estimated VO2max). Associations were evaluated with and without considering pattern of ST by bout length. We measured ST and activity by a wrist-worn accelerometer, FMI by bioelectrical impedance, and VO2max by Pacer test in 443 children (51.2% girls, 10.2 ± 0.6 years). Isotemporal substitution regression models estimated the effects of substituting ST, LPA, and MVPA on FMI and VO2max. Further models repeated analyses separating ST into short (<10 min) and long (≥10 min) bouts. Only replacing ST or LPA with MVPA was consistently associated with lower FMI and greater VO2max. When separated by bout length, only one unique association was found where replacing long ST bouts with short ST bouts was associated with lower FMI in girls only. In conclusion, activity pattern is associated with adiposity in girls and fitness in boys and girls. Separating ST into long and short ST bouts may be of minimal importance when assessing associations with adiposity and fitness using wrist-worn accelerometry in children.

Physical Fitness across 11- to 17-Year-Old Adolescents: A Cross-Sectional Study in 2267 Austrian Middle- and High-School Students

Puberty is a critical period in the development of physical fitness. The purpose of this study, therefore, was to examine the development of various components of physical fitness in Austrian adolescents between 11 and 17 years of age. A total of 2267 (51% male) adolescents from 18 secondary schools in Western Austria provided valid data. Following anthropometric measurements, participants performed the German motor test, which consists of 8 test items that assess speed, power, strength, endurance, agility, balance, and flexibility. Differences in physical fitness by age and sex were examined via a 2 by 7 MANOVA. In general, fitness improved between the ages 11 and 13 years in boys and girls. After the age of 13, physical fitness remained relatively stable in girls, while there was a continuous increase in physical fitness in boys, except for flexibility, which remained stable. Accordingly, boys performed better than girls, except for flexibility, which was better in girls. No sex difference occurred for balance. Biological changes (e.g. changes in sex hormones, body composition), contribute to significant gains in strength and endurance throughout adolescence, particularly in boys. In girls, increases in physical fitness were less pronounced and were generally limited after the age of 13. This may also reflect behavioral changes and emphasizes the importance of continued promotion of physical activity and sports, particularly in girls.