Physical activity throughout adolescence and body composition at 18 years: 1993 Pelotas (Brazil) birth cohort study

Body Composition and Physical Activity in Pediatric Intestinal Failure On and Off Parenteral Nutrition

OBJECTIVES

Data on the relationship between body composition (BC) and physical activity (PA) in children with intestinal failure (IF) are lacking. The objectives were to collect data on PA and BC in children with IF, both parenterally and enterally fed, and to assess the relationship between PA and BC.

METHODS

Cross-sectional study in children 5-18 years with IF including those receiving parenteral nutrition (PN) and those fully enterally fed. PA levels were measured using accelerometry. BC was measured by dual-energy X-ray absorptiometry. Data were compared to age- and sex-matched population norms using t tests. Regression analysis assessed the relationship between BC and PA.

RESULTS

Fifty-eight children with IF (38 males), mean (SD) age of 10.0 (3.5) years, 20 dependent on PN were included. Patients with IF had significantly fewer steps per day ( P ≤ 0.001) compared with literature controls, with a mean (SD) of 7,972 (3,008) and 11,749 (1,106), respectively. There were no significant differences between patients receiving PN and those enterally fed, but both groups were significantly less active than literature controls ( P < 0.001). Patients with IF had higher fat mass and lower fat-free mass compared to literature controls ( P = 0.008). PA had a significant effect on BC ( r2 = 0.32, P < 0.001).

CONCLUSIONS

Children with IF, those receiving PN and those fully enterally fed, are at risk of decreased PA and altered BC. PA should be part of ongoing rehabilitation and management to optimize outcomes.

The Joint Associations of Physical Activity and Sedentary Behaviors on Adiposity during Adolescence: The 1993 Pelotas (Brazil) Cohort Study

A prior study conducted in high-income countries demonstrated that specific sedentary behavior, such as TV viewing, is prospectively associated with adiposity in both active and inactive adolescents. The aim of this study was to examine the joint associations of sedentary behaviors and moderate- and vigorous-intensity physical activity (MVPA) with adiposity among Brazilian adolescents. This prospective cohort study included 377 participants of the 1993 Pelotas (Brazil) Study who completed an accelerometry assessment at age 13 years and a dual-energy X-ray absorptiometry (DXA) assessment at age 18 years. Accelerometer-measured MVPA was dichotomized into high (≥60 min/day) and low (<60 min/day). Accelerometer-measured sedentary time (SED) was dichotomized into low (<49 min/h) and high (≥49 min/h) based on the median. Self-reported TV viewing time was also dichotomized into low (<3 h/day) and high (≥3 h/day) based on the median. We combined the two MVPA groups (high and low) and two SED groups (low and high) to form the four MVPA&SED groups: high&low, high&high, low&low, and low&high. We also created four MVPA&TV groups in the same manner. Fat mass index (FMI; kg/m2) was calculated using DXA-derived fat mass. Multivariable linear regression analyses compared FMI at 18 years among the four MVPA&SED groups and among the four MVPA&TV groups, adjusting for socioeconomic status, energy intake, and baseline adiposity. The analysis results showed that SED or TV viewing time was not prospectively associated with adiposity in both active and inactive Brazilian adolescents. This study suggests that the association between specific sedentary behaviors, such as TV viewing, and adiposity may differ across societal settings-in this case, high-income vs. middle-income countries.

Longitudinal change in physical activity and adiposity in the transition from adolescence to early adulthood: the 1993 Pelotas cohort study

Background

In the current Physical Activity Guidelines (PAG) for moderate- and vigorous-intensity physical activity (MVPA), abrupt transition from ≥ 60 min/day [youth PAG] to ≥ 150 min/week (≥ 22 min/day on average) [adult PAG] during emerging adulthood is poorly justified. The aim of this study was to examine body fat mass changes according to whether meeting the youth and adult PAGs in late adolescence (age 18 years) to early adulthood (age 22 years).

Methods

The study sample included 2,099 participants (1,113 females) from the 1993 Pelotas (Brazil) Study. At ages 18 and 22 years, MVPA was measured using wrist-worn accelerometry and fat mass was measured using dual-energy X-ray absorptiometry. MVPA at age 18 was categorized into two groups: 0–59 or ≥ 60 min/day (no [N] or yes [Y] for meeting the youth recommendation, respectively). MVPA at age 22 was categorized into three groups: 0–21, 22–59, or ≥ 60 min/day (N, Y22, or Y60 for not meeting the adult recommendation, meeting the adult recommendation, or meeting the youth recommendation, respectively). The combination of these groups created six MVPA groups (N&N, N&Y22, N&Y60, Y&N, Y&Y22, and Y&Y60). Sex-specific multivariable linear regression analyses were conducted to estimate change in fat mass index (FMI) from age 18 to 22 years in the six MVPA groups.

Results

Among males, compared to Y&Y60 (FMI increase = 1.2 kg/m² [95% CI = 1.0, 1.4]), Y&Y22 and Y&N had larger FMI increases (1.9 [1.6, 2.1] and 1.9 [1.2, 2.5], respectively). Among females, Y&Y60 and Y&Y22 had an equal FMI increase (1.6 [1.4, 1.9] for both groups), while Y&N had a larger FMI increase (2.4 [1.8, 3.0]).

Conclusions

These findings suggest that among those who were active in late adolescence, engaging in ≥ 22 min/day of MVPA in adulthood is associated with lower body fat gain for females, but not for males.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12966-022-01321-0.

Height-adjusted lean body mass and its associations with physical activity and kidney function in pediatric kidney transplantation

BACKGROUND

Although LBM is positively associated with health outcomes, studies assessing determinants for the accrual of ht-LBM, such as physical activity, are limited. This study aimed to assess ht-LBM levels in pediatric kidney transplant recipients and test its association with baseline and contemporaneous variables, including physical activity.

METHODS

A retrospective cross-sectional review was performed on 46 pediatric kidney transplant recipients, and a longitudinal review was performed on a subset of recipients with serial post-transplant (n = 21) and pre/post-transplant (n = 11) ht-LBM measurements. Ht-LBM measurements were obtained using DXA scans.

RESULTS

This cohort was 16.0 (IQR 12.3, 17.7) years old, 56.5% male and 46 ± 45 months post-transplant with a mean ht-LBM of 15.1 ± 2.5 kg/m² . A median ht-LBM increase of 1.6 kg/m² (IQR - 0.1, 2.6 kg/m² ; p < .01) was observed, over 29.2 ± 12.0 months from the earliest post-transplant scan obtained at 46 ± 25 months post-transplant until the most recent post-transplant scan. A 1.7 ± 1.4 kg/m² (p < .01) increase was observed between pre- and post-transplant DXA scans which were taken at 12 ± 11 months pre-transplant and 13 ± 6 months post-transplant, respectively. In separate adjusted models, lower physical activity questionnaire scores (n = 17, beta = 1.55, p = .02), faster rate of estimated glomerular filtration rate decline (beta = 0.05, p < .048) adjusted for annualized change in BSA, and younger age at scan (beta = 0.32, p < .01) were each significant predictors of lower ht-LBM.

CONCLUSIONS

Physical activity and kidney function may influence ht-LBM in the pediatric kidney transplant population.

Effects of Substituting Sedentary Behavior with Light-Intensity or Moderate-to-Vigorous Physical Activity on Obesity Indices in Adults: A Prospective Short-Term Follow-Up Study

BACKGROUND

Sedentary behavior (SB) is an independent risk factor for cardiovascular diseases. We hypothesized that there may be benefits of replacing SB with light-intensity (LIPA) and moderate-to-vigorous (MVPA) physical activity. Substituting SB with LIPA and MVPA might be associated with body composition changes.

METHODS

We assessed body weight, body mass index (BMI), fat body mass (FBM), and physical activity level, as well as one-year changes, in 780 adults (EPIMOV Study).

RESULTS

We analyzed into 10-min blocks SB, LIPA, MVPA, and total wear time. After 14 ± 3 months of follow-up, there were 242 completed procedures. We reallocated time spent in SB to LIPA or MVPA and assessed cross-sectional and prospective associations with the outcomes using isotemporal substitution models. In cross-sectional analysis, substituting 10-min blocks of SB with MVPA led to significant decreases of 1.23 kg in body weight, 0.30 kg/m² in BMI, and 0.38% in FBM. 10-min blocks substituting SB with LIPA produced significantly lower body weight (1 kg) and BMI (0.1 kg/m²) values. In longitudinal analysis, reallocating SB to MVPA was only associated with FBM decline (-0.31%).

CONCLUSIONS

Substituting SB with MVPA is associated with significant improvement in obesity indices in both cross-sectional and follow-up. Replacing SB with LIPA produced a less consistent impact.

Associations between Spanish children's physical activity and physical fitness with lean body mass: The CALINA study

The present study investigated the associations between physical activity (PA) and physical fitness (PF) with lean body mass (LBM) and evaluated whether PA mediates the association between PF and LBM. 279 children (150 boys) aged 7.5 ± 0.3 years participated in the study. PA was assessed by accelerometry and PF with handgrip and the standing long jump test. Total lean soft tissue mass index (TLSTMI), muscle cross-sectional area index (MCSAI), and fat-free mass index (FFMI) were evaluated using dual-energy X-ray absorptiometry, peripheral quantitative computed tomography, and bioimpedance analysis, respectively.Total (β = 0.247) and vigorous PA (β = 0.143) were associated with TLSTMI in girls. In boys, total (β = 0.337), light (β = 0.290), vigorous (β = 0.200), and moderate-vigorous PA (β = 0.189) were associated with TLSTMI. Total PA was associated with FFMI (β = 0.299). Handgrip strength does not mediate the relationship between total PA and TLSTMI. Positive associations were found between handgrip strength and TLSTMI, MCSAI, and FFMI in both girls and boys.In children, there is a positive association between total and vigorous PA with TLSTMI. Handgrip strength does not mediate the relationship between total PA and TLSTMI. It was associated with TLSTMI, MCSAI, and FFMI.

Physical activity and fat-free mass during growth and in later life

BACKGROUND

Physical activity may be a way to increase and maintain fat-free mass (FFM) in later life, similar to the prevention of fractures by increasing peak bone mass.

OBJECTIVES

A study is presented of the association between FFM and physical activity in relation to age.

METHODS

In a cross-sectional study, FFM was analyzed in relation to physical activity in a large participant group as compiled in the International Atomic Energy Agency Doubly Labeled Water database. The database included 2000 participants, age 3-96 y, with measurements of total energy expenditure (TEE) and resting energy expenditure (REE) to allow calculation of physical activity level (PAL = TEE/REE), and calculation of FFM from isotope dilution.

RESULTS

PAL was a main determinant of body composition at all ages. Models with age, fat mass (FM), and PAL explained 76% and 85% of the variation in FFM in females and males < 18 y old, and 32% and 47% of the variation in FFM in females and males ≥ 18 y old, respectively. In participants < 18 y old, mean FM-adjusted FFM was 1.7 kg (95% CI: 0.1, 3.2 kg) and 3.4 kg (95% CI: 1.0, 5.6 kg) higher in a very active participant with PAL = 2.0 than in a sedentary participant with PAL = 1.5, for females and males, respectively. At age 18 y, height and FM-adjusted FFM was 3.6 kg (95% CI: 2.8, 4.4 kg) and 4.4 kg (95% CI: 3.2, 5.7 kg) higher, and at age 80 y 0.7 kg (95% CI: -0.2, 1.7 kg) and 1.0 kg (95% CI: -0.1, 2.1 kg) higher, in a participant with PAL = 2.0 than in a participant with PAL = 1.5, for females and males, respectively.

CONCLUSIONS

If these associations are causal, they suggest physical activity is a major determinant of body composition as reflected in peak FFM, and that a physically active lifestyle can only partly protect against loss of FFM in aging adults.

Sports Participation from Childhood to Adolescence is Associated with Lower Body Dissatisfaction in Boys-A Sex-Specific Analysis

OBJECTIVES

This study aimed to analyze the association between body dissatisfaction and sports participation from childhood to adolescence in a school-based sample of adolescents, according to sex.

METHODS

A total of 1011 adolescents of 13.1 ± 2.3 years of age were evaluated. Body dissatisfaction was assessed by the Silhouettes Scale and sports participation for at least one consecutive year was retrospectively assessed by closed specific questions related to childhood and adolescence periods. Body mass index (BMI) and abdominal obesity were objectively measured. Habitual practice of physical activity (PA), socioeconomic status (SES), and ethnicity were assessed through questionnaires.

RESULTS

Sports participation from childhood to adolescence was observed in 55.1% of boys and in 41.2% of girls. Boys with body dissatisfaction showed lower habitual PA in leisure time (Baecke score = 4.38 ± 2.27 vs. 5.15 ± 2.25, p < 0.05) and in total (Baecke score = 9.34 ± 2.64 vs. 9.96 ± 2.68, p < 0.05) than those who were satisfied. No differences were observed among girls. Sports participation from childhood to adolescence was associated with 42% less chance of having body dissatisfaction in boys (OR = 0.58 [95%CI = 0.36-0.94]). No significant association was observed among girls.

CONCLUSIONS FOR PRACTICE

Sports participation from childhood to adolescence was negatively associated with body dissatisfaction in boys. The continuity of physical activity during youth may be an important modifiable factor to reduce body dissatisfaction.

Dietary Protein Requirements in Children: Methods for Consideration

The current protein requirement estimates in children were largely determined from studies using the nitrogen balance technique, which has been criticized for potentially underestimating protein needs. Indeed, recent advances in stable isotope techniques suggests protein requirement as much as 60% higher than current recommendations. Furthermore, there is not a separate recommendation for children who engage in higher levels of physical activity. The current evidence suggests that physical activity increases protein requirements to support accretion of lean body masses from adaptations to exercise. The indicator amino acid oxidation and the ¹⁵N-end product methods represent alternatives to the nitrogen balance technique for estimating protein requirements. Several newer methods, such as the virtual biopsy approach and ²H₃-creatine dilution method could also be deployed to inform about pediatric protein requirements, although their validity and reproducibility is still under investigation. Based on the current evidence, the Dietary Reference Intakes for protein indicate that children 4–13 years and 14–18 years require 0.95 and 0.85 g·kg⁻¹·day⁻¹, respectively, based on the classic nitrogen balance technique. There are not enough published data to overturn these estimates; however, this is a much-needed area of research.

Adolescent physical activity, sedentary behavior and sleep in relation to body composition at age 18 years in urban South Africa, Birth-to-Twenty+ Cohort

Background

Adolescence is marked by a decline in physical activity, rapid physical growth and changes in body composition, which have been linked to body composition. Prospective data on these associations are rare, particularly in Africa.

Aim

The aim of this study was to examine the association of longitudinal patterns across adolescent in physical activity, sedentary behavior and sleep, with anthropometry and body composition at age 18 years in urban South Africa.

Methods

We analyzed data from the Birth-to-Twenty Plus Cohort (Bt20+), a longitudinal study of children born in 1990 in Soweto-Johannesburg, South Africa. We used general linear models to investigate the association of adolescent (ages 12 to 18 years) longitudinal trends in physical activity, sedentary behavior and schoolnight sleep and overall physical activity patterns, with body mass index (BMI), waist circumference, fat mass index (FMI), lean mass index (LMI) and percent body fat at age 18 years.

Results

The final study sample included 1337 participants with anthropometric measurements (52% female) and 958 participants with body composition measurements (53% female). Males who were consistently more active and consistently walked to school over adolescence had lower waist circumference (B = − 2.0, 95% CI: − 3.9 to − 0.2), FMI (B = − 0.8, 95%: CI: − 1.2 to − 0.1) and percent body fat (B = -2.9, 95% CI: − 4.9 to − 0.9) at age 18 years than those who decreased activity and did not walk to school. Consistently-sedentary females had higher waist circumference than those whose sedentary behavior increased over adolescence (B = 5.4, 95% CI: 0.2 to 10.6). Males who reported sleeping 9 h or more per night on schoolnights had significantly lower BMI (B = -1.0, 95% CI: − 1.4 to- 0.5), and percent body fat (B = -1.5, 95%CI − 2.8 to − 0.1) than those who reported sleeping 8 h or less per night.

Conclusion

Patterns of adolescent physical activity, sedentary behavior and sleep are related to young-adult body composition in urban South Africa. These modifiable behaviors may be paths for public health interventions to curb overweight and obesity in many low- or middle-income countries.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-020-02451-9.

Eveningness in Energy Intake among Adolescents with Implication on Anthropometric Indicators of Nutritional Status: The CRO-PALS Longitudinal Study

Shifting of energy intake towards a later time in the day is associated with an increased risk of obesity in adults. However, there is a lack of data for adolescents. The aim of this study was to investigate adolescents eveningness in energy intake (EV) and its association with anthropometric indicators of nutritional status. This investigation was based on results from the Croatian physical activity in adolescence longitudinal study (CRO-PALS). The cohort included 607 adolescents (50.25% females and 49.75% males) who were assessed at the age of 15/16 and 18/19. A single multi-pass 24-h recall was used as a dietary assessment method, while anthropometric indicators of nutritional status included body mass index (BMI), waist to hip ratio (WHR) and the sum of four skinfolds. The School Health Action, Planning and Evaluation System (SHAPES) questionnaire was used to assess active daily energy expenditure and sedentary behaviors. EV was significantly higher at 18/19 years compared to 15/16 years in whole population (p < 0.01), among male adolescents (p < 0.01), but not among female adolescents (p > 0.05). Although a significant correlation between EV and WHR was found in females at the age of 15/16 (p < 0.01), the results of this study suggest that EV has no or a minor effect on anthropometric indicators of nutritional status in adolescence.

Longitudinal changes in body composition and waist circumference by self-reported levels of physical activity in leisure among adolescents: the Tromsø study, Fit Futures

Background

It is not clear how physical activity affects body composition in adolescents. Physical activity levels are often reduced during this period, and the relative proportion of body fat mass and lean mass undergo natural changes in growing adolescents. We aimed to examine whether self-reported physical activity in leisure time at baseline or change in activity during follow-up affect changes in four measures of body composition; body mass index (kg/m²), waist circumference, fat mass index (fat mass in kg/m²) and lean mass index (lean mass in kg/m²).

Methods

We used data from the Tromsø Study Fit Futures, which invited all first year students in upper secondary high school in two municipalities in northern Norway in 2010–2011. They were reexamined in 2012–2013. Longitudinal data was available for 292 boys and 354 girls. We used multiple linear regression analyses to assess whether self-reported level of physical activity in leisure time at baseline predicted changes in body composition, and analysis of covariance to assess the effects of change in level of activity during follow-up on change in body composition. All analyses were performed sex-specific, and a p-value of < 0.05 was considered statistically significant.

Results

There were no associations between self-reported leisure time physical activity in the first year of upper secondary high school and changes in any of the considered measure of body composition after 2 years of follow up, with the exception of waist circumference in boys (p = 0.05). In boys, change in fat mass index differed significantly between groups of activity change (p < 0.01), with boys adopting activity or remaining physically active having less increase in fat mass index than the consistently inactive. In girls, change in lean mass index differed significantly between groups of activity change (p = 0.04), with girls adopting physical activity having the highest increase.

Conclusions

Self-reported leisure time physical activity does not predict changes in body composition in adolescents after 2 years of follow up. Change in the level of physical activity is associated with change in fat mass index in boys and lean mass index in girls.

Position Statement: Exercise Guidelines to Increase Peak Bone Mass in Adolescents

Background

An increase in bone mineral density during adolescence increases resistance to fractures in older age. The Korean Society for Bone and Mineral Research and the Korean Society of Exercise Physiology developed exercise guidelines to increase the peak bone mass (PBM) in adolescents based on evidence through a systematic review of previous research.

Methods

Articles were selected using the systematic method, and the exercise guidelines were established by selecting key questions (KQs) and defining the effects of exercises based on evidence through a literature review for selecting the final exercise method. There were 9 KQs. An online search was conducted on articles published since 2000, and 93 articles were identified.

Results

An increase in PBM in adolescence was effective for preventing osteoporosis and fractures in older age. Exercise programs as part of vigorous physical activity (VPA) including resistance and impact exercise at least 5 to 6 months were effective for improving PBM in adolescents. It is recommended that resistance exercise is performed 10 to 12 rep·set⁻¹ 1-2 set·region⁻¹ and 3 days·week⁻¹ using the large muscles. For impact exercises such as jumping, it is recommended that the exercise is performed at least 50 jumps·min⁻¹, 10 min·day⁻¹ and 2 days·week⁻¹.

Conclusions

Exercise guidelines were successfully developed, and they recommend at least 5 to 6 months of VPA, which includes both resistance and impact exercises. With the development of exercise guidelines, the incidence of osteoporosis and fractures in the aging society can be reduced in the future, thus contributing to improved public health.

Metabolic implications of low muscle mass in the pediatric population: a critical review

Skeletal muscle is recognized as a tissue with high metabolic capacity given its key roles in glucose and lipid metabolism. Although low muscle mass has been associated with metabolic disorders in adults, it is not clear if this body composition phenotype is related to metabolic health status earlier in life. In this review, we aim to clarify whether having low muscle mass is associated with increased risk of metabolic dysregulation in the pediatric population. Fifteen original articles investigating the relationship between body composition measures of muscle mass and single or clustered metabolic risk factors in children and adolescents were critically evaluated. Despite a growing body of evidence supporting low muscle mass as a risk factor for metabolic health in children and adolescents, conflicting associations were reported. Differences in body composition techniques, muscle mass indices, and clinical methods used to assess metabolic biomarkers may have contributed to a lack of a consistent conclusion. Moreover, most studies did not control for potential biological and lifestyle confounders. Future studies using precise, reproducible techniques to evaluate body composition and metabolic biomarkers are required to determine the implications of low muscle mass on metabolic health during childhood and adolescence.

The Importance of Pedestrian Network Connectivity for Adolescent Health: A Cross-sectional Examination of Associations between Neighbourhood Built Environments and Metabolic Health in the Pacific Islands Families Birth Cohort Study

The research aim was to investigate associations between objectively-assessed built environment attributes and metabolic risk in adolescents of Pacific Islands ethnicity, and to consider the possible mediating effect of physical activity and sedentary time. Youth (n = 204) undertook a suite of physical assessments including body composition, blood sampling, and blood pressure measurements, and seven day accelerometry. Objective measures of the neighbourhood built environment were generated around individual addresses. Logistic regression and linear modelling were used to assess associations between environment measures and metabolic health, accounting for physical activity behaviours. Higher pedestrian connectivity was associated with an increase in the chance of having any International Diabetes Federation metabolic risk factors for males only. Pedestrian connectivity was related to fat free mass in males in unadjusted analyses only. This study provides evidence for the importance of pedestrian network connectivity for health in adolescent males. Future research is required to expand the limited evidence in neighbourhood environments and adolescent metabolic health.

Is vigorous-intensity physical activity required for improving bone mass in adolescence? Findings from a Brazilian birth cohort

The association between moderate and vigorous physical activity throughout adolescence and areal bone density (aBMD) at 18 years of age was evaluated. Vigorous-intensity physical activity at 11, 15, and 18 years was associated with aBMD in early adulthood, especially in boys. Cross-sectional analyses showed a positive association between moderate physical activity and aBMD.

INTRODUCTION

To evaluate independent associations of moderate and vigorous physical activity (MPA, VPA) across adolescence with areal bone mineral density (aBMD).

METHODS

Physical activity (PA) was assessed at 11, 15, and 18 years of age by self-report and at 18 years by accelerometry in the 1993 Pelotas Birth Cohort Study. Time spent in MPA and VPA was determined using metabolic equivalents and specific cutoffs based on raw acceleration. Lumbar spine and femoral neck aBMD were measured by DXA at 18 years. Statistical analyses evaluated the association of MPA and VPA with aBMD, after adjusting for skin color, asset index, current height and age at menarche, and peak strain score (based on ground reaction forces of PA).

RESULTS

Lumbar spine and femoral neck aBMD were available for 3947 (49.9% of boys) and 3960 (49.6% of boys) individuals, respectively. Time spent in MPA at 11 and 15 years was not associated with aBMD. VPA at all time points was positively related to both lumbar spine and femoral neck aBMD in boys. Results were consistent for objectively measured VPA. Girls who achieved 75+ minutes/week of VPA in at least two follow-ups showed higher aBMD at 18 years of age. Boys who reached 75+ minutes/week of VPA at all follow-ups had on average 0.117 g/cm² (95% CI: 0.090; 0.144) higher femoral neck aBMD than those who never achieved this threshold.

CONCLUSIONS

Self-reported VPA but not MPA throughout adolescence was associated with aBMD. Recommendation for PA in young people should consider the importance of VPA.

Self-reported physical activity during leisure time was favourably associated with body composition in Norwegian adolescents

AIM

We studied the cross-sectional association between self-reported physical activity and body composition in adolescents.

METHODS

The Norwegian Fit Futures Cohort Study was conducted in the Tromsø and Balsfjord municipalities during 2010-2011. All 1,117 students in their first year of upper secondary high school were invited to attend an examination at the Clinical Research Unit at the University Hospital of Northern Norway and 93% agreed. After exclusions, we analysed 945 participants (51% boys) with a mean age of 16.1 years (range 15.5-17.5 years) with valid measurements. The associations between self-reported weekly hours of physical activity during leisure time and four measures of body composition were explored using linear regression.

RESULTS

Self-reported physical activity was significantly associated with the fat mass index (p < 0.03) and lean mass index (p < 0.001) in both genders. The lean mass index increased with higher levels of activity and the fat mass index decreased. Physical activity was not associated with body mass index for either gender, but there was an inverse association with waist circumference in girls (p = 0.04).

CONCLUSION

Physical activity was favourably associated with body composition in Norwegian adolescents and showed contrasting associations with the fat mass and lean mass indexes.

Low muscle mass and strength in pediatrics patients: Why should we care?

Skeletal muscle plays major roles in metabolism and overall health across the lifecycle. Emerging evidence indicates that prenatal (maternal diet during pregnancy and genetic defects) and postnatal factors (physical activity, hormones, dietary protein, and obesity) influence muscle mass acquisition and strength early in life. As a consequence, low muscle mass and strength contributes to several adverse health outcomes during childhood. Specifically, studies demonstrated inverse associations of muscle mass and strength to single and clustered metabolic risk factors. The literature also consistently reports that low muscle mass and strength are associated with reduced bone parameters during growth, increasing the risk of osteoporosis in old age. Furthermore, muscle mass gains are associated with improved neurodevelopment in the first years of life. Given these negative implications of low muscle mass and strength on health, it is crucial to track muscle mass and strength development from childhood to adolescence. Several body composition techniques are currently available for estimation of muscle mass, all with unique advantages and disadvantages. The value of ultrasound as a technique to measure muscle mass is emerging in pediatric research with potential for translating the research findings to clinical settings. For the assessment of muscle strength, the handgrip strength test has been widely employed but without a standardized protocol. Although further research is needed to define normative data and cut points for the low muscle mass and strength phenotype, the use of such non-invasive medical monitoring is a promising strategy to identify early abnormalities and prevent low muscle mass in adulthood.

Associations between muscle mass, physical activity and dietary behaviour in adolescents

BACKGROUND AND OBJECTIVES

Investigations in older individuals suggest that adequate nutrition and physical activity are particularly important to skeletal muscle health; however, data in adolescents are scant and equivocal. The objective was to determine the associations among diet, physical activity and skeletal muscle mass in adolescents.

METHODS

We assessed diet with four to seven 24-h recalls and physical activity by accelerometry in 640 adolescents. Using total body measures of fat-free soft tissue mass and fat mass assessed by dual-energy X-ray absorptiometry, the skeletal muscle mass index (SMMI) was derived by adjusting fat-free soft tissue mass for fat mass in addition to height.

RESULTS

Skeletal muscle mass index (SMMI) was negatively associated with consumption of sugar-sweetened beverages (standardized beta coefficient [β] = -0.10, P = 0.001) and saturated fats (β = -0.28, P < 0.001). SMMI was positively associated with physical activity (moderate + vigorous) (β = 0.20, P < 0.001). In further analysis, we observed a significant interaction between physical activity and sugar-sweetened beverage intake on SMMI (P = 0.002).

CONCLUSION

Our study in adolescence suggests that physical activity and consumption of both sugar-sweetened beverages and saturated fats are associated with skeletal muscle mass. More importantly, our findings suggest that sugar-sweetened beverage intake may attenuate the beneficial effects of physical activity on skeletal muscle mass.

Associations between self-reported physical activity and screen time with cardiometabolic risk factors in adolescents: Findings from the 1993 Pelotas (Brazil) Birth Cohort Study

The overall aim of this study was to examine the association of physical activity (PA) and screen time (ST) on indicators of cardio-metabolic risk during adolescence, by examining the combined association of PA and ST at ages 11, 15 and 18 on cardio-metabolic risk factors at 18 years. Data from the 1993 Pelotas (Brazil) Birth Cohort Study (N = 3613) were analysed in 2017. Self-reported PA and ST data were collected at 11, 15 and 18 years. Cardio-metabolic risk factors (fat mass index, waist circumference, triglycerides, blood glucose, non-HDL cholesterol and resting diastolic blood pressure) were examined at age 18. Multivariate linear regression was used to examine the associations between four mutually exclusive PA/ST groups: 1) active (≥1 h/day PA) and low ST (<5 h/day ST); 2) active (≥1 h/day PA) and high ST (≥5 h/day ST); 3) inactive (<1 h/day PA) and low ST (<5 h/day ST); 4) inactive (<1 h/day PA) and high ST (≥5 h/day ST) at each age, and outcomes at age 18. There were no significant associations between PA/ST at ages 11 and 15 with outcomes at 18 years. In the cross-sectional analyses, adolescents in the most active group had significantly better levels of all the outcomes, regardless of ST. Inactive participants with high ST had the highest levels of glucose and non-HDL-C. For diastolic blood pressure, values were higher among inactive participants. Overall, higher levels of physical activity appeared to be more important than low levels of ST for cardio-metabolic health in adolescents.

Protein Metabolism in Active Youth: Not Just Little Adults

Understanding how exercise and dietary protein alter the turnover and synthesis of body proteins in youth can provide guidelines for the optimal development of lean mass. This review hypothesizes that active youth obtain similar anabolic benefits from exercise and dietary protein as adults, but the requirement for amino acids to support growth renders them more sensitive to these nutrients.

Agreement Between Standard Body Composition Methods to Estimate Percentage of Body Fat in Young Male Athletes

PURPOSE

To examine the intermethods agreement of dual-energy X-ray absorptiometry (DXA) and foot-to-foot bioelectrical impedance analysis (BIA) to assess the percentage of body fat (%BF) in young male athletes using air-displacement plethysmography (ADP) as the reference method.

METHODS

Standard measurement protocols were carried out in 104 athletes (40 swimmers, 37 footballers, and 27 cyclists, aged 12-14 y).

RESULTS

Age-adjusted %BF ADP and %BF BIA were significantly higher in swimmers than footballers. ADP correlates better with DXA than with BIA (r = .84 vs r = .60, P < .001). %BF was lower when measured by DXA and BIA than ADP (P < .001), and the bias was higher when comparing ADP versus BIA than ADP versus DXA. The intraclass correlation coefficients between DXA and ADP showed a good to excellent agreement (r = .67-.79), though it was poor when BIA was compared with ADP (r = .26-.49). The ranges of agreement were wider when comparing BIA with ADP than DXA with ADP.

CONCLUSION

DXA and BIA seem to underestimate %BF in young male athletes compared with ADP. Furthermore, the bias significantly increases with %BF in the BIA measurements. At the individual level, BIA and DXA do not seem to predict %BF precisely compared with ADP in young athletic populations.

Upper and lower limbs composition: a comparison between anthropometry and dual-energy X-ray absorptiometry in healthy people

The detection of changes in lean mass (LM) distribution can help to prevent disability. This study assessed the degree of association between anthropometric measurements and dual-energy X-ray absorptiometry (DXA) body composition (BC) parameters of the upper and lower limbs in a healthy general population and collected DXA age- and sex-specific values of BC that can be useful to build a reference standard.

PURPOSE

The primary aim of this study was to investigate the reliability of some widely available anthropometric measurements in the assessment of body composition (BC) at the limbs, especially in terms of muscle mass, in a large sample of healthy subjects of different age bands and sex, using fat mass (FM) and lean mass (LM) parameters derived by dual-energy X-ray absorptiometry (DXA) as the gold standard. The secondary aim was to collect DXA age- and sex-specific values of BC of left and right limbs (upper and lower) in a healthy Italian population to be used as reference standards.

METHODS

Two hundred fifty healthy volunteers were enrolled. Arm circumference (AC) and thigh circumference (ThC) were measured, and total and regional BC parameters were obtained by a whole-body DXA scan (Lunar iDXA, Madison, WI, USA; enCORE™ 2011 software version 13.6).

RESULTS

FM/LM showed only fair correlation with AC and ThC in females (r = 0.649 and 0.532, respectively); in males and in the total population, the correlation was low (r = 0.360 or lower, and p non-statistically significant). AC and ThC were not well representative of arms LM in both genders (females r = 0.452, males r = 0.530) independently of age. In general, men of all age groups showed higher values of LM and lean mass index (LMI) in both total and segmental upper and lower limbs. In males, the maximum LM and LMI were achieved in the fifth decade in both upper and lower limbs and then started to decrease with aging. In females, no significant modification with aging was identified in LM and LMI.

CONCLUSION

According to our results, anthropometry is not well representative of LM of arms in both genders, independently of age; therefore, a densitometric examination should be considered for a correct assessment of BC at limbs.

Associations between accelerometer-measured physical activity and body fatness in school-aged children

Background

The main aim of the study was to examine the cross-sectional associations between objectively measured physical activity (PA) and body fatness in 7–12-year-old children.

Methods

We performed an analysis of 365 children (209 girls). Participant recruitment was performed in eight randomly selected elementary schools in cities and towns with various numbers of inhabitants. The body composition analysis was performed according to a multi-frequency bioelectrical impedance analysis; PA was monitored using an accelerometer.

Results

In terms of the overall PA, boys were more active than girls. No significant associations (unadjusted and adjusted models) were found between light PA and all body fatness indicators in either sex. Moderate-to-vigorous PA was significantly negatively associated with all body fatness indicators only in girls. These associations strengthened after adjustment for age, height and sedentary time (β ranging from –0.49 to –0.36, P ≤ 0.01). In contrast, vigorous PA was strongly negatively associated with body fatness indicators only in boys. In the fully adjusted model the significant negative associations were found for fat mass percentage (β = –0.15, P = 0.048) and fat mass index (β = –0.15, P = 0.040).

Conclusions

The present study suggests that increasing sex-specific PA of different intensities may be an appropriate approach for decreasing body fatness in children. Longitudinal studies are needed to verify these associations.