Fat-free mass mediates the association between birth weight and aerobic fitness in youth

Longitudinal development and tracking of cardiorespiratory fitness from childhood to adolescence

BACKGROUND

Cardiorespiratory fitness (CRF) is an important indicator of health in childhood and adolescence but longitudinal studies on the development and tracking of CRF from childhood to adolescence are scarce.

OBJECTIVES

The objectives of this study were (1) to assess longitudinal development and track CRF over 10 years from childhood to adolescence, and (2) to examine potential sex differences in the development and tracking of CRF during this period.

METHODS

Participants were Icelandic children born in 1999, measured at the age of 7 (n = 190, 106 girls), 9 (n = 163, 95 girls), 15 (n = 239, 134 girls), and 17 (n = 202, 119 girls). CRF was assessed with a maximal cycle ergometer test and expressed as maximal power output (Max W) and maximal power output relative to lean mass (W/kgLM). Multilevel regression models were used to study the longitudinal development of CRF, and tracking was assessed with Spearman's rank correlation, logistic regression, and the percentage of participants remaining in low, moderate, or high CRF categories between measurements.

RESULTS

Max W and W/kgLM increased for both boys and girls up to age 15. Max W plateaued for both boys and girls while W/kgLM plateaued for girls but declined for boys from age 15 to 17. Boys had higher Max W than girls from age 15 and higher W/kgLM from age 9. CRF tracked at low to moderate levels from childhood to adolescence and at high levels in adolescence, with higher values observed for boys than girls.

CONCLUSIONS

Age 15 was a critical time point in the development of CRF, with values starting to plateau for girls and decline for boys. The results support early intervention for improved CRF in later years, with interventions targeting all children, regardless of their CRF level.

The relationship in early childhood body composition and physical activity levels regarding fundamental motor skill development

BACKGROUND

Fundamental motor skills (FMS) are considered essential for sport participation and might be deficit in obese children. While evidence indicates that physical activity (PA) levels impact motor skill development, the relationship between body composition, PA, and motor competence, particularly in early childhood, is not thoroughly understood. We aimed to determine if PA, fat mass (FM), and fat-free mass (FFM) are predictors of FMS.

METHODS

Preschoolers (n = 47) from two preschools were assessed for FMS, PA, and body composition. Peabody Developmental Motor Scales (PDMS-2) subscale scores were used to assess FMS. PA was assessed with a wrist-worn accelerometer for five days during school. FM and FFM were measured with foot-to-foot bioelectrical impedance.

RESULTS

Linear regressions indicate significant models for stationary skills (SS) (F = 4.57, p = .004) and object manipulation skills (OMS) (F = 4.66, p = .003). FFM was the only significant predictor of SS (t = 3.98, p < .001) and OMS (t = 3.50, p = .001). FM and all intensities of PA were nonsignificant predictors in all models.

CONCLUSIONS

These results indicate that interventions that target improving or maintaining FFM may improve FMS.

Birth Weight was Favorably Associated With Physical Fitness in Childhood After Adjustment for Several Perinatal Factors

BACKGROUND

The purpose was to examine the potential associations of birth weight and infant growth with physical fitness (PF) components in childhood.

METHOD

A random sample of 5125 dyads of children aged 8-9 years and their mothers were evaluated. Telephone interviews were carried out with the use of a standardized questionnaire for the collection of maternal lifestyle factors. Mothers were asked to provide information contained in their medical booklets and pregnancy ultrasound records. Data from 5 PF tests were used to assess cardiorespiratory fitness, speed, and body strength. Linear regression analysis was applied to assess the associations between birth weight and infant growth with PF test performances and logistic regression analysis to evaluate the associations of normal weight versus low birth weight and normal versus accelerated infant growth with PF tests performance categories (low vs high/average).

RESULTS

Birth weight was favorably associated with cardiorespiratory fitness (b = 0.12 stage increase per SD increase in birth weight, P = .047), lower body strength (b = 1.07, P = .037), upper body strength (b = 0.10, P = .038), and speed (b = -0.04, P = .001), and infant growth was associated with upper body strength (b = 0.21 cm increase per SD increase in infant weight gain, P < .001) after adjusting for children's body mass index and several perinatal factors. Low birth weight children had 35% increased odds for low performances in PF tests compared with their normal birth weight counterparts.

CONCLUSION

Low birth weight negatively affects childhood PF, and hence, it could play an unfavorable role in the future health of the offspring.

Pre- and post-natal factors and physical activity in childhood: The Norwegian Mother, Father and Child Cohort study

Few studies have examined the possibility that pre- and post-natal factors may be non-linearly associated with later physical activity. We used data from the Norwegian Mother, Father and Child Cohort study (MoBa) and the Medical Birth Registry of Norway (MBRN), including 48 672 children with available data on leisure time physical activity (LTPA) at child's age 7 years. Restricted cubic and linear splines or linear regression was used to examine the associations between maternal pre-pregnancy BMI, birth weight for gestational age, and infant weight gain from birth to 1 year with LTPA (frequency/wk) in 7-year-old children. The results suggest no associations between maternal pre-pregnancy BMI, birth weight, and infant weight gain on subsequent LTPA in girls. Maternal pre-pregnancy BMI and birth weight may be non-linearly associated with LTPA in 7-year-old boys. Infant weight gain (change in weight z-score from birth to 1 year) may be weakly linearly associated with LTPA in boys. Pre- and post-natal factors may therefore influence LTPA in childhood differently in boys and girls. Maternal pre-pregnancy BMI and birth weight are positively associated with LTPA at the lower ends of the maternal pre-pregnancy BMI and birth weight continuums in boys. The negative associations at the higher ends of the continuums and the positive association between infant weight gain and LTPA in boys may not be important and needs further replication.

Birth Weight and Cardiorespiratory Fitness Among Young Men Born at Term: The Role of Genetic and Environmental Factors

Background Preterm delivery and low birth weight are prospectively associated with low cardiorespiratory fitness (CRF). However, whether birth weight, within the at-term range, is associated with later CRF is largely unknown. Thus, the aim of the current study was to examine this issue and whether such association, if any, is explained by shared and/or nonshared familial factors. Methods and Results We conducted a prospective cohort study, including 286 761 young male adults and a subset of 52 544 siblings born at-term. Objectively measured data were retrieved from total population registers. CRF was tested at conscription and defined as the maximal load obtained on a cycle ergometer. We used linear and nonlinear and fixed-effects regression analyses to explore associations between birth weight and CRF. Higher birth weight, within the at-term range, was strongly associated with increasing CRF in a linear fashion. Each SD increase in birth weight was associated with an increase of 7.9 (95% CI, 7.8-8.1) and 6.6 (95% CI; 5.9-7.3) Wmax in the total and sibling cohorts, respectively. The association did not vary with young adulthood body mass index. Conclusions Birth weight is strongly associated with increasing CRF in young adulthood among men born at-term, across all categories of body mass index. This association appears to be mainly driven by factors that are not shared between siblings. Hence, CRF may to some extent be determined already in utero. Prevention of low birth weight, also within the at-term-range, can be a feasible mean of increasing adult CRF and health.

The level of physical fitness in children aged 6-7years with low birthweight

BACKGROUND

Level of physical fitness is related to the functional status of most of the bodily functions and so it appears to be very important to identify perinatal factors influencing physical fitness.

AIM

The purpose of this study was to determine the influence of birth weight on the level of physical fitness in children 6-7years of age.

SUBJECTS AND METHOD

Physical fitness was assessed using EUROFIT tests in 28,623 children, aged 6-7years, from rural areas in Poland. Children below the 10th percentile for birth weight for gestational age were defined as small for gestational age (SGA). The influence of birth weight on parameters of fitness was assessed by means of covariance analysis.

RESULTS

With the controls of age, sex and body size, children of low birth weight have shown significantly lower levels of body flexibility and running speed. The leg strength of children with SGA turned out to be significantly lower only in 7-year-old boys.

CONCLUSION

This study has revealed the significant influence of birth weight on physical fitness. The results suggest the importance of early intervention and its possible benefits for developing and maintaining the proper level of physical fitness further in life.

Overcoming birth weight: can physical activity mitigate birth weight-related differences in adiposity?

BACKGROUND

Individuals born at low or high birth weight (BW) have elevated adiposity. The extent to which physical activity can mitigate this risk is unknown.

OBJECTIVES

The aim of this study was to determine if associations between BW and adiposity vary by self-reported moderate-to-vigorous physical activity (MVPA) among adolescents.

METHODS

We used data on adolescents in the National Health and Nutrition Examination Survey (1999-2006; 12-15 years; n = 4064). Using gender-stratified linear regression, we modelled body mass index (BMI) and waist circumference (WC) z-scores as a function of low, normal and high BW, MVPA (weekly Metabolic Equivalent of Task hours) and MVPA*BW cross-product terms, adjusting for sociodemographics, diet and, in WC models, BMI.

RESULTS

Among girls with low MVPA, those born with high BW had greater BMI than normal BW; this difference diminished with greater MVPA (coefficient [95% confidence interval]: low MVPA: 0.72 [0.29, 1.14]; high MVPA: -0.04 [-0.48, 0.39]; P for interaction = 0.05). Among boys, MVPA did not modify the associations between BW and BMI. WC was unrelated to BW, regardless of MVPA.

CONCLUSIONS

Findings suggest that effects of high BW in total adiposity can be more easily modified with MVPA in adolescent girls than in boys.

The Link between Fetal Programming, Inflammation, Muscular Strength, and Blood Pressure

Hypertension affects one billion individuals worldwide and is considered the leading cause of cardiovascular death, stroke, and myocardial infarction. This increase in the burden of hypertension and cardiovascular diseases (CVD) is principally driven by lifestyle changes such as increased hypercaloric diets and reduced physical activity producing an increase of obesity, insulin resistance, and low-grade inflammation. Visceral adipocytes are the principal source of proinflammatory cytokines and systemic inflammation participates in several steps in the development of CVD. However, maternal and infant malnutrition also persists as a major public health issue in low- to middle-income regions such as Latin America (LA). We propose that the increased rates of cardiovascular and metabolic diseases in these countries could be the result of the discrepancy between a restricted nutritional environment during fetal development and early life, and a nutritionally abundant environment during adulthood. Maternal undernutrition, which may manifest in lower birth weight offspring, appears to accentuate the relative risk of chronic disease at lower levels of adiposity. Therefore, LA populations may be more vulnerable to the pathogenic consequences of obesity than individuals with similar lifestyles in high-income countries, which may be mediated by higher levels of proinflammatory markers and lower levels of muscle mass and strength observed in low birth weight individuals.

Associations between organized sports participation and objectively measured physical activity, sedentary time and weight status in youth

OBJECTIVES

The purpose of this study was to examine whether participation in organized sports is related to achieving physical activity recommendations, body mass index (BMI), objectively measured PA intensity and time spent sedentary.

DESIGN

Cross-sectional study.

METHODS

The sample comprised 973 children and adolescents (427 boys, 546 girls) aged 10-18 years (Mage=14.1±2.4). Organized sport was self-reported. Physical activity and time spent in moderate and vigorous intensity PA (MVPA) and sedentary time was assessed with accelerometers.

RESULTS

More boys (51.3%) than girls (28.3%) reported to be involved in organized sports participation (p<0.001). Those who were engaged in organized sports were more likely to achieve physical activity guidelines (OR=1.64, 95% CI: 1.14-2.35, p<0.01), spent more time in MPA (OR=1.01, 95% CI: 1.01-1.02, p<0.01), VPA (OR=1.09, 95% CI: 1.05-1.13, p<0.001), and MVPA (OR=1.01, 95% CI: 1.01-1.02, p<0.001) than those who did not participate in organized sports. No associations between organised sport participation and time spent sedentary or BMI was observed.

CONCLUSIONS

Engagement in organized sports is related to higher levels of objectively measured MPA, VPA and achieving the recommended levels of MVPA in youth; however participation in sports appears unrelated to time spent sedentary and BMI. Our results suggest that promoting organised sport may increase physical activity of at least moderate intensity in young people.

Low muscle strength is associated with metabolic risk factors in Colombian children: the ACFIES study

Purpose

In youth, poor cardiorespiratory and muscular strength are associated with elevated metabolic risk factors. However, studies examining associations between strength and risk factors have been done exclusively in high income countries, and largely in Caucasian cohorts. The aim of this study was to assess these interactions in schoolchildren in Colombia, a middle income Latin American country.

Methods

We measured body mass index, body composition, handgrip strength (HG), cardiorespiratory fitness (CRF) and metabolic risk factors in 669 low-middle socioeconomic status Colombian schoolchildren (mean age 11.52±1.13, 47% female). Associations between HG, CRF and metabolic risk factors were evaluated.

Results

HG and CRF were inversely associated with blood pressure, HOMA index and a composite metabolic risk score (p<0.001 for all) and HG was also inversely associated with triglycerides and C-reactive protein (CRP) (both p<0.05). Associations between HG and risk factors were marginally weakened after adjusting for CRF, while associations between CRF and these factors were substantially weakened after adjusting for HG. Linear regression analyses showed inverse associations between HG and systolic BP (β = −0.101; p = 0.047), diastolic BP (β = −0.241; p> = 0.001), HOMA (β = −0.164; p = 0.005), triglycerides (β = −0.583; p = 0.026) and CRP (β = −0.183; p = 0.037) but not glucose (p = 0.698) or HDL cholesterol (p = 0.132). The odds ratios for having clustered risk in the weakest quartile compared with the strongest quartile were 3.0 (95% confidence interval: 1.81–4.95).

Conclusions

In Colombian schoolchildren both poorer handgrip strength/kg body mass and cardiorespiratory fitness were associated with a worse metabolic risk profile. Associations were stronger and more consistent between handgrip and risk factors than between cardiorespiratory fitness and these risk factors. Our findings indicate the addition of handgrip dynamometry to non-invasive youth health surveillance programs would improve the accuracy of the assessment of cardio-metabolic health.