Permanent deficits in handgrip strength and running speed performance in low birth weight children

Influence of Preterm Birth and Low Birthweight on Physical Fitness: A Systematic Review, Meta-Analysis, and Meta-Regression

BACKGROUND

Preterm birth and low birthweight (LBW) might be associated with reduced physical fitness, although evidence remains inconclusive.

OBJECTIVE

To examine the influence of preterm birth and LBW on physical fitness, as well as to assess whether variables such as gestational age, birthweight, or age at assessment moderate these effects.

METHODS

PubMed, Scopus, and PsycINFO were systematically searched from inception to 7 December 2023 for case-control and cohort studies analyzing the association between preterm birth or LBW (or gestational age or birthweight as continuous variables) with at least one physical fitness-related outcome (i.e., cardiorespiratory fitness (CRF), muscle strength, flexibility, speed, agility). Random-effects meta-analysis and meta-regression models were used to estimate the pooled effect size, as well as to examine potential associations between the magnitude of the effect and gestational age, birthweight, or age at assessment.

RESULTS

Fifty-two studies (n = 920,603 participants, average age ranging from 4.7 to 34.4 years) were included. Preterm birth was associated with reduced CRF (standardized mean difference (SMD) = -0.38, 95% confidence interval (CI) = -0.51 to -0.25) and muscle strength (SMD = -0.44, 95% CI = -0.79 to -0.08). LBW was associated with reduced CRF (SMD = -0.40, 95% CI = -0.64 to -0.17), muscle strength (SMD = -0.18, 95% CI = -0.24 to -0.13), flexibility (SMD = -0.11, 95% CI = -0.22 to -0.01), and agility (SMD = -0.99, 95% CI = -1.91 to -0.07). Meta-regression analyses showed that a lower gestational age or birthweight were associated with larger reductions in physical fitness, whereas no consistent association was found for the age at assessment.

CONCLUSION

Both preterm birth and LBW seem associated with reduced physical fitness regardless of age, with larger reductions overall observed in individuals with lower gestational age or birthweight. These findings might support the implementation of preventive strategies (e.g., fitness monitoring and physical exercise interventions) in these populations through the life course. PROSPERO registration: CRD42021231845.

Exploring the association between grip strength and adverse pregnancy and perinatal outcomes: A Mendelian randomization study

Background

Previous observational studies have demonstrated an association between grip strength and detrimental pregnancy and perinatal outcomes. However, the causality of this relationship remains uncertain.

Objective

This study aims to investigate if there is a causal relationship between grip strength and adverse pregnancy and perinatal outcomes, providing evidence to support active intervention for adverse pregnancy outcomes.

Study design

A two-sample Mendelian randomization method was used to select GWAS data from the UK Biobank and the FinnGen Biobank as data sources. The inverse variance weighting method was used as the main analysis method. The reliability of the results was verified through sensitivity analysis, including Cochran's Q test, MR-egger intercept regression analysis, leave-one-out analysis, and funnel plot. Independent queues are also used to verify the reliability of the results.

Results

The study demonstrated a significant positive correlation between genetically predicted hand grip strength and offspring birth weight, specifically left-hand grip strength (β = 0.193, 95 % CI: 0.099-0.286, p = 0.0001) and right-hand grip strength (β = 0.310, 95 % CI: 0.235-0.384, p = 3.27E-16). Sensitivity analysis indicated no horizontal multi-effect, and leave-one-out analysis along with the funnel plot showed no abnormalities. The verification queue also yielded similar results.

Conclusion

This study revealed a significant association between grip strength-related traits and offspring birth weight, suggesting a potential protective effect. Moreover, a negative predictive trend was observed for other adverse pregnancy outcomes. Modifying grip strength through an active lifestyle and continuous monitoring of pregnant women's grip strength may have implications for improving pregnancy outcomes. However, further research is warranted to investigate these findings more comprehensively.

Prevalence and risk factors of low birth weight in the United States: An analysis of 2016-2021 data

BACKGROUND

Low birthweight (LBW), infants weighing less than 2,500 g, is a global health concern associated with high infant morbidity and mortality rates. This study investigates LBW prevalence and its relation to maternal sociodemographic characteristics and lifestyle behaviors factors in the United States (US).

METHODS

This analysis used the National Survey of Children's Health (NSCH) data from 2016 to 2021, including n = 225,443 children aged 0-17 years. 18,131 had LBW (<2,500 g), and 2810 had very LBW (VLBW) (<1,500 g). Logistic regression calculated odds ratios (OR) using LBW as the dependent variable, adjusting for various factors.

RESULTS

Between 2016 and 2021 in the United States, LBW prevalence averaged 9.31%, with VLBW at 1.50%. Mothers aged 18-35, White, had the lowest LBW (7.63%) and VLBW (1.17%) rates. Mothers aged ≤18 years, black, had the highest LBW (15.45%) and VLBW infants (4.70%). Maternal age emerged as a significant LBW factor, with an OR of 1.27 for ≤18 and 1.19 for >35. Children in poor health had the highest OR (2.87). Race/ethnicity and other disparities were observed.

CONCLUSION

Our study highlights LBW risk among non-White mothers with specific criteria, emphasizing the need for continued exploration of intersectional targets for change that are exacerbating LBW disparities among marginalized populations which may be artificially attributed to biologic determinants and individual-level risk factors. In-depth analysis of repressive structures at the root of inequalities demand continued research on macro levels of influence. Customized healthcare reform holds the greatest potential to disrupt the patterns contributing to poor health outcomes among LBW children, and will ultimately maximize the reach and effectiveness of health promotion strategies and clinical practices aimed to improve universal maternal and infant health.

The Effect of Preterm Birth on Maximal Aerobic Exercise Capacity and Lung Function in Healthy Adults: A Systematic Review and Meta-analysis

BACKGROUND

A negative impact of premature birth on health in adulthood is well established. However, it is not clear whether healthy adults who were born prematurely but have similar physical activity levels compared to adults born at term have a reduced maximal aerobic exercise capacity (maximum oxygen consumption [VO2max]).

OBJECTIVE

We aimed to determine the effect of premature birth on aerobic exercise capacity and lung function in otherwise healthy, physically active individuals.

METHODS

A broad literature search was conducted in the PubMed database. Search terms included 'preterm/premature birth' and 'aerobic exercise capacity'. Maximal oxygen consumption (mL/kg/min) was the main variable required for inclusion, and amongst those investigations forced expiratory volume in 1 s (FEV1, % predicted) was evaluated as a secondary parameter. For the systematic review, 29 eligible articles were identified. Importantly, for the meta-analysis, only studies which reported similar activity levels between healthy controls and the preterm group/s were included, resulting in 11 articles for the VO2max analysis (total n = 688, n = 333 preterm and n = 355 controls) and six articles for the FEV1 analysis (total n = 296, n = 147 preterm and n = 149 controls). Data were analysed using Review Manager ( Review Manager. RevMan version 5.4 software. The Cochrane Collaboration; 2020.).

RESULTS

The systematic review highlighted the broad biological impact of premature birth. While the current literature tends to suggest that there may be a negative impact of premature birth on both VO2max and FEV1, several studies did not control for the potential influence of differing physical activity levels between study groups, thus justifying a focused meta-analysis of selected studies. Our meta-analysis strongly suggests that prematurely born humans who are otherwise healthy do have a reduced VO2max (mean difference: - 4.40 [95% confidence interval - 6.02, - 2.78] mL/kg/min, p < 0.00001, test for overall effect: Z = 5.32) and FEV1 (mean difference - 9.22 [95% confidence interval - 13.54, - 4.89] % predicted, p < 0.0001, test for overall effect: Z = 4.18) independent of physical activity levels.

CONCLUSIONS

Whilst the current literature contains mixed findings on the effects of premature birth on VO2max and FEV1, our focused meta-analysis suggests that even when physical activity levels are similar, there is a clear reduction in VO2max and FEV1 in adults born prematurely. Therefore, future studies should carefully investigate the underlying determinants of the reduced VO2max and FEV1 in humans born preterm, and develop strategies to improve their maximal aerobic capacity and lung function beyond physical activity interventions.

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.

Inter-individual variability in children's physical growth and body composition: Findings of longitudinal ELOS-Pré study

BACKGROUND

Children's physical growth (PG) and body composition (BC) can be influenced by birth weight and type of delivery.

AIM

To longitudinally analyze the dynamics of PG and BC of children from 5 to 9 years; to investigate the inter-individual differences according to age, sex, BW, and type of delivery across the following years of the study.

SUBJECTS AND METHODS

A total of 1236 children (597 boys) were evaluated at 5-years of age and followed annually until 9-years. PG and BC measurements were evaluated. Multilevel modeling was used.

RESULTS

Annual increments were observed (p < .001). Girls presented lower height and fat-free-mass but higher %BF (p < .001). Distinct trajectories between the sexes were observed for height (p < .001). Low-birth-weight children presented lower height, body mass, and fat-free-mass (p < .001), but the interaction between velocity of growth and BC was significant only in height (p < .05). Children born by had lower height, body mass, and %BF, and gained less body mass per year than those born by vaginal delivery (p < .05). Significant inter-individual differences were observed at 5-years of age and in their trajectories, except for fat-free-mass (p < .01).

CONCLUSION

There are differences in the dynamics of PG and BC, low-birth-weight and type of delivery influence the dynamics of PG during this interval of ages.

Post-exercise hypotension effects in response to plyometric training of 7- to 9-year-old boys with overweight/obesity: a randomized controlled study

BACKGROUND

Physical activity plays an important role on children with obesity. This study evaluated the effects of plyometric training on the anthropometry, body composition, and the blood pressure (BP) and heart rate (HR) of boys with obesity.

METHODS

Boys aged 7 to 9 years old were divided in: non-trained (N.=12) and trained (N.=29). The plyometric training program consisted of jumps on nonconsecutive days for twelve weeks. Anthropometry and body composition, BP and HR were evaluated. BP, HR and rate-pressure product were recorded at rest and 2 minutes after the section. Two-way repeated factors ANOVA was used.

RESULTS

Trained group had a reduction in skinfolds and an increase in free fat mass (within and between-groups) and a large effect size for most anthropometric and body composition variables. Late systolic response was reduced from 122±1.1 (immediately post-exercise at the first week) to 112±1.0 at the end of plyometric training period. Diastolic reduction was seen two minutes after each session of exercise (from 68±1.1 to 62±1.2). HR was reduced in response to plyometric training (108 bpm to 97 bpm).

CONCLUSIONS

Our findings strengthen previous studies that suggest that intense exercise has significant adaptive effects on BP and HR.

Analysis of Children's Physical Characteristics Based on Clustering Analysis

This study assessed the physical development, physical fitness (muscular endurance, muscular strength, flexibility, agility, power, balance), and basal metabolic rate (BMR) in a total of 4410 children aged six (73–84 months) residing in Korea. Their physical fitness was visually classified according to the physical fitness factor and—considering that children showed great variations in the physical fitness criteria depending on their physique and body composition—the study aimed to assess characteristics such as physique and BMR, the precursor for fat-free mass, based on the physical health clusters selected through a multivariate approach. As a result, the physical health clusters could be subdivided into four clusters: balance (1), muscular strength (2), low agility (3), and low physical fitness (3) cluster. Cluster 1 showed a high ratio of slim and slightly slim children, while cluster 2 had a high proportion of children that were obese, tall, or heavy, and had the highest BMR. We consider such results as important primary data for constituting physical fitness management programs customized to each cluster. It seems that it is necessary to have a multidirectional approach toward physical fitness evaluation and analysis methodologies that involve various physical fitness factors of children.

Low birth weight and its relation to physical fitness parameters in children: Its negative effect on muscle strength and cardiorespiratory endurance

BACKGROUND

There is increasing evidence that low birth weight has a negative effect on physical fitness, muscle strength, and cardiorespiratory endurance, although the findings are inconsistent.

OBJECTIVES

This study aimed to evaluate whether birth weight acts as a prenatal determinant of physical fitness parameters and to determine the role of environmental or biological variables on this effect.

METHODS

One hundred and sixty-seven children aged 6-14 years were included in this study. The anthropometric data, physical activity index, standing long jump, flexibility, handgrip strength, and cardiorespiratory fitness were evaluated.

RESULTS

A positive correlation was found between birth weight and cardiorespiratory fitness (r = .349; p < .001), right handgrip strength (r = .337; p < .001), and left handgrip strength (r = .320; p < .001), suggesting that children with low birth weight had the worst performance in both cardiorespiratory endurance and grip strength tests. These findings remained significant after adjustment for prematurity, sex, age, physical activity index, and body mass index (BMI). Stepwise multiple regression analyses revealed a significant interaction of high birth weight, older age, and low BMI in predicting better cardiorespiratory endurance (R² = .308). When handgrip strength was tested as the dependent variable, we found that high birth weight, male sex, and older age emerged as important determinants for both sides.

CONCLUSION

Children aged 6-14 years born with a birth weight < 2.5 kg have low handgrip strength and cardiorespiratory fitness, which seems to be mediated partially by influences of both prenatal environment (e.g., birth weight) and biological variables (e.g., age, sex, BMI).

The mediation effect of anthropometry and physical fitness on the relationship between birthweight and basal metabolic rate in children

BACKGROUND

Birthweight (BW) has been associated with anthropometry, body composition and physical fitness during growth and development of children. However, less is known about the mediation effect of those variables on the relationship between BW and basal metabolic rate (BMR) in children.

OBJECTIVE

To analyse the mediation effect of anthropometry, body composition and physical fitness on the association between BW and BMR in children.

METHODS

In total, 499 children (254 boys, 245 girls) aged 7-10 years were included. Anthropometry (weight, height, head, waist and hip circumferences), body composition (skinfolds thickness, body fat percentage), physical fitness (handgrip strength, flexibility, muscular endurance, muscular explosive power, agility, running speed) and BMR were evaluated. The analyses were conducted by: single-mediator analysis (SMA) and multi-mediator analysis (MMA).

RESULTS

The SMA indicates height, head, waist and hip circumferences and handgrip strength as significant mediators of BW on BMR for boys and height, hip circumference and handgrip strength as significant mediators of BW on BMR for girls. In MMA for girls, there were significant indirect effects for height, hip circumference and handgrip strength, with 79.08% of percent mediation. For boys, the head and waist circumferences mediation had a significant indirect effect, with 83.37% of percent mediation.

CONCLUSION

The anthropometric variables associated with BW were body height, head, hip and waist circumferences for boys and body height and hip circumference for girls. The current study provides new evidence that height and handgrip strength during childhood mediated the relationship between BW and BMR.

Effects of Zika infection on growth

OBJECTIVES

To present the currently available evidence of the effects of congenital Zika virus infection on infant growth, to discuss possible intervening factors, and to describe preliminary data on this growth in a cohort of exposed children.

SOURCE OF DATA

Non-systematic review in PubMed, BVS, CAPES, Scopus, Web of Science, Cochrane and Google Scholar databases in the last 5 years, using the terms infection/disease by Zika virus and growth/nutrition/nutritional status/infant nutrition and nutritional needs. Additionally, the anthropometric data of the first 2.5 years of a cohort of children exposed to the Zika virus during pregnancy were reviewed.

SYNTHESIS OF DATA

Both intrauterine growth restriction and low birth weight were reported in series of cases of children with congenital Zika syndrome. The postnatal growth deficit of these children appears to be directly proportional to the degree of neurological impairment. The etiology is multifactorial, and nutritional and non-nutritional factors are probably involved. The data from the present cohort show that the head circumference evolution depends on this measurement at birth and that weight-height growth has a trend toward lower weight and length in children with congenital microcephaly and normocephalic at birth who develop some neurological abnormality.

CONCLUSIONS

The few existing data suggest that, in children with congenital Zika, the greater the degree of neurological impairment, the greater the impact on growth, whether or not associated with microcephaly at birth.

A multi-level analysis of individual- and school-level correlates of physical fitness in children

BACKGROUND

Children's physical fitness is potentially influenced by biological, behavioural and environmental factors.

AIM

To investigate the importance of individual-level and school-level characteristics in explaining variation in children's physical fitness.

SUBJECTS AND METHODS

The sample comprised 354 Portuguese children, aged 5-10 years. Physical fitness [(handgrip (HG) strength, standing long jump (SLJ), shuttle-run (SR), total physical fitness score (PFz)], gross motor coordination (GMC) and body mass index (BMI) were assessed. Moderate-to-vigorous physical activity (MVPA) was objectively monitored; birth weight and socio-economic status (SES) were obtained by questionnaire. School contexts were assessed via an objective audit. Multilevel models using the Bayesian approach were used.

RESULTS

Age was positively associated with HG, SLJ and PFz (p < 0.05); BMI was positively associated with HG (p < 0.05) and GMC with all physical fitness components (p < 0.05); MVPA was only associated with PFz (p < 0.05); children with level A SES outperformed those with level C SES in HG (p < 0.05), but those with level B SES outperformed their level A SES peers in SR (p < 0.05). Within the school context, no equipment for physical education was negatively associated with HG (p < 0.05).

CONCLUSION

In the primary school years, individual-level characteristics were more important than the school context in explaining variations in physical fitness.

Is willingness to exercise programmed in utero? Reviewing sedentary behavior and the benefits of physical activity in intrauterine growth restricted individuals

OBJECTIVE

The literature suggests that a fetus will adapt to surrounding adversities by optimizing its use of energy to improve survival, ultimately leading to the programming of the individual's energy intake and expenditure. While recent reviews focused on the fetal programming of energy intake and food preferences, there is also some evidence that fetal adversity is associated with diminished physical activity levels. Therefore, we aimed to review (a) the evidence for an association between being born with intrauterine growth restriction and sedentarism over the life-course and (b) the potential benefits of physical activity over cardiometabolic risk factors for this population.

SOURCES

PubMed, Scielo, Scopus and Embase.

SUMMARY OF FINDINGS

Most clinical studies that used objective measures found no association between intrauterine growth restriction and physical activity levels, while most studies that used self-reported questionnaires revealed such relationships, particularly leisure time physical activity. Experimental studies support the existence of fetal programming of physical activity, and show that exposure to exercise during IUGR individuals' life improves metabolic outcomes but less effect was seen on muscle architecture or function.

CONCLUSIONS

Alterations in muscle strength and metabolism, as well as altered aerobic performance, may predispose IUGR individuals to be spontaneously less physically active, suggesting that this population may be an important target for preventive interventions. Although very heterogeneous, the different studies allow us to infer that physical activity may have beneficial effects especially for individuals that are more vulnerable to metabolic modifications such as those with IUGR.

Twelve Weeks of Plyometric Training Improves Motor Performance of 7- to 9-Year-Old Boys Who Were Overweight/Obese: A Randomized Controlled Intervention

Nobre, GG, de Almeida, MB, Nobre, IG, dos Santos, FK, Brinco, RA, Arruda-Lima, TR, de-Vasconcelos, KL, de-Lima, JG, Borba-Neto, ME, Damasceno-Rodrigues, EM, Santos-Silva, SM, Leandro, CG, and Moura-dos-Santos, MA. Twelve weeks of plyometric training improves motor performance of 7- to 9-year-old boys who were overweight/obese: a randomized controlled intervention. J Strength Cond Res 31(8): 2091-2099, 2017-The prevalence of childhood overweight/obesity has increased, and physical training at school may to be effective to combat this scenario. We analyzed the effects of a protocol of plyometric training on body composition and motor performance of boys who were overweight/obese aged 7-9 years. The sample was randomly assigned into 2 groups: plyometric training group (T, n = 40) and control group (C, n = 19). Training consisted of 20 min·d (twice a week, during 12 weeks) of lower extremity plyometric exercise. Health-related physical fitness was measured by handgrip strength, standing long jump (SLJ), curl-ups, sit and reach, square test, running speed, and mile run test. Gross motor coordination was evaluated by means of the Körperkoordinations-test für Kinder (KTK) tests. Baseline and postintervention differences were investigated, and effect size was estimated through Cohen's d coefficient. Both groups showed increased body weight, height, and sitting height after intervention with a negligible effect size. Only T group showed increased fat-free mass (p = 0.011) compared with baseline values with small effect size. Plyometric training improved handgrip strength (d = 0.23), sit and reach (d = 0.18), curl-ups (d = 0.39), SLJ (d = 0.80), agility (d = 0.48), and time in the mile run test (d = 0.38). For gross motor coordination results, T group showed better performance in all tests after plyometric training with moderate/large effect size. Thus, 12 weeks of PT improved health-related physical fitness components and motor coordination acquisition of 7- to 9-year-old boys who were overweight/obese.

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.

Deficits in anthropometric indices of nutritional status and motor performance among low birth weight children from Maputo City, Mozambique

OBJECTIVE

To evaluate associations between low birth weight (LBW) and anthropometry, body composition, physical fitness, and gross motor coordination among schoolchildren from Maputo, Mozambique.

METHODS

A total of 353 children aged 7 to 10 years old from both genders born in Maputo (Mozambique) were sampled. The sample was divided into two groups: LBW (n = 155) and normal birth weight (NBW, n = 198). Body composition measurements and indices weight-for-age, height-for-age, and weight-for-height were assessed. Physical fitness was assessed by handgrip strength, flexibility, agility, long jump, and running speed. Gross motor coordination was evaluated by using the Korper Koordination Test fur Kinder (KTK) battery.

RESULTS

LBW children were lighter and smaller than NBW children with reduced indices for weight-for-age and height-for-age. They also showed a reduced performance in handgrip strength and sideways movement tests. These differences remained significant even after adjustment for age, gender, body size, and fatness skinfold thickness.

CONCLUSION

LBW seems to be the major factor that influences anthropometry, and is a predictor of low muscle strength and low performance on sideways movement tests. This result suggests that growth faltering in LBW children is associated with adverse health consequences, even after controlling for gender, age, fatness, and body size.

Transcriptional response of skeletal muscle to a low protein perinatal diet in rat offspring at different ages: The role of key enzymes of glucose-fatty acid oxidation

Skeletal muscle is a plastic tissue during development with distinctive acute and chronic response to maternal protein restriction. This study evaluated gene and protein expression of key-enzymes of glycolytic pathway (HK2, PFK, PDK4 and CS), and fatty acid oxidation (CPT1 and β-HAD) of two different types of skeletal muscle [soleus and extensor digitorium longus (EDL)] from offspring rats at 30 and 90 days of age, exposed to maternal isoenergetic low protein diet throughout gestation and lactation. Pups from dams fed 17% protein diet (n=5, normal protein, Np), and low protein pups from dams fed 8% casein diet (low protein, Lp, n=5) were evaluated. Offspring were sacrificed either 30 or 90 days old. Soleus and EDL were analyzed for mRNA and protein expression by quantitative PCR and western blotting, respectively. Soleus was more affected by Lp maternal diet at 90 days by down-regulation of key enzymes of glycolytic pathway, in particular HK2 and PDK4 with a concomitant reduction of β-HAD mRNA. For EDL, the effects of Lp maternal diet were more pronounced at 30 days, as the transcriptional key enzymes of glycolytic pathway were down-regulated. One important finding was that the observed acute (30 days) transcriptional changes did not remain in adult Lp rats (90 days), except for PDK4. The robust PDK4 mRNA down-regulation, observed in both soleus and EDL, and at both ages, and the consequent down-regulation of the PDK4 protein expression can be responsible for a state of reduced metabolic flexibility of skeletal muscle in response to maternal low protein diet.

Impact of placental insufficiency on fetal skeletal muscle growth

Intrauterine growth restriction (IUGR) caused by placental insufficiency is one of the most common and complex problems in perinatology, with no known cure. In pregnancies affected by placental insufficiency, a poorly functioning placenta restricts nutrient supply to the fetus and prevents normal fetal growth. Among other significant deficits in organ development, the IUGR fetus characteristically has less lean body and skeletal muscle mass than their appropriately-grown counterparts. Reduced skeletal muscle growth is not fully compensated after birth, as individuals who were born small for gestational age (SGA) from IUGR have persistent reductions in muscle mass and strength into adulthood. The consequences of restricted muscle growth and accelerated postnatal "catch-up" growth in the form of adiposity may contribute to the increased later life risk for visceral adiposity, peripheral insulin resistance, diabetes, and cardiovascular disease in individuals who were formerly IUGR. This review will discuss how an insufficient placenta results in impaired fetal skeletal muscle growth and how lifelong reductions in muscle mass might contribute to increased metabolic disease risk in this vulnerable population.

Low birth weight, very low birth weight and extremely low birth weight in African children aged between 0 and 5 years old: a systematic review

Low birth weight (LBW<2500), very low birth weight (VLBW<1500), extremely low birth weight (ELBW<1500) infants are at high risk for growth failure that result in delayed development. Africa is a continent that presents high rates of children born with LBW, VLBW and ELBW particularly sub-Saharan Africa. To review the existing literature that explores the repercussions of LBW, VLBW and ELBW on growth, neurodevelopmental outcome and mortality in African children aged 0–5 years old. A systematic review of peer-reviewed articles using Academic Search Complete in the following databases: PubMed, Scopus and Scholar Google. Quantitatives studies that investigated the association between LBW, VLBW, ELBW with growth, neurodevelopmental outcome and mortality, published between 2008 and 2015 were included. African studies with humans were eligible for inclusion. From the total of 2205 articles, 12 articles were identified as relevant and were subsequently reviewed in full version. Significant associations were found between LBW, VLBW and ELBW with growth, neurodevelopmental outcome and mortality. Surviving VLBW and ELBW showed increased risk of death, growth retardation and delayed neurodevelopment. Post-neonatal interventions need to be carried out in order to minimize the short-term effects of VLBW and ELBW.

PHYSICAL FITNESS AND BIRTH WEIGHT IN YOUNG MEN FROM MAPUTO CITY, MOZAMBIQUE

ABSTRACT Introduction: Birth weight has been considered an important marker of the nutritional transition in developing countries. Objective: To evaluate the influence of birth weight on body composition and physical fitness of young men born in Maputo, Mozambique. Methods: One hundred and seventy-nine students (aged 19 to 22 years) were divided into four groups (low birth weight < 2.500 g, LBW, n = 49; insufficient birth weight ≥ 2.500 g and < 3.000 g, IBW, n = 27; normal birth weight ≥ 3.000 g and < 3.999 g, NBW, n = 74; and high birth weight > 3.999 g, HBW, n = 31). Anthropometry and body composition were measured. Physical fitness was assessed by handgrip strength, muscle endurance, flexibility, agility, and running speed. Results: IBW showed lower values of body mass and fat free mass while LBW and HBW had high values of hip circumference, suprailiac, subscapular and abdominal skinfold when compared to NBW. LBW and HBW showed a high percentage of individuals with low performance in flexibility, right handgrip, agility, abdominal resistance, arms strength, and horizontal long jump. Around 70% of HBW showed low performance in the running speed test. Conclusion: Both low and high birth weight can influence adult adiposity and the performance in physical fitness tests.

Birthweight, body composition, and motor performance in 7- to 10-year-old children

AIM

The aim of this study was to analyse the influence of birthweight on motor performance and body composition in children. Further, we investigated whether associations between birthweight and motor performance changed after adjustment for current height, body mass index (BMI), fat-free mass (FFM), and % body fat.

METHOD

A total of 483 children (251 males and 232 females) aged 7 to 10 years (mean 8.78, SD 1.0y) born in Vitória Santo Antão (northeast Brazil) were sampled. Motor performance was operationalized using different physical fitness components and gross motor coordination. Physical fitness was measured by handgrip strength, muscle endurance, explosive power, flexibility, agility, running speed, and maximal oxygen consumption (VO2max). Gross motor coordination was evaluated by means of the Körper Koordination Test für Kinder (KTK).

RESULTS

Positive correlations between birthweight and height, BMI, and FFM were found. Birthweight was positively correlated with handgrip strength and negatively correlated with 20-meter sprint time, even after controlling for age, height, BMI, FFM, and % body fat. Birthweight was negatively associated with relative VO2max (mL/kg/min); however, the association was no longer significant after inclusion of BMI or FFM in the model.

INTERPRETATION

Birthweight significantly predicted height, BMI, FFM, and performance in strength and velocity tests, but did not influence gross motor coordination.

Analytical strategies in human growth research

Human growth research requires knowledge of longitudinal statistical methods that can be analytically challenging. Even the assessment of growth between two ages is not as simple as subtracting the first measurement from the second, for example. This article provides an overview of the key analytical strategies available to human biologists in increasing order of complexity, starting with a review on how to express cross-sectional measurements of size, before covering growth (conditional regression models, regression with conditional growth measures), growth curves (individual growth curves, mixed effects growth curves, latent growth curves), and patterns of growth (growth mixture modeling). The article is not a statistical treatise and has been written by a human biologist for human biologists; as such, it should be accessible to anyone with training in at least basic statistics. A summary table linking each analytical strategy to its applications is provided to help investigators match their hypotheses and measurement schedules to an analysis plan. In addition, worked examples using data on non-Hispanic white participants in the Fels Longitudinal Study are used to illustrate how the analytical strategies might be applied to gain novel insight into human growth and its determinants and consequences. All too often, serial measurements are treated as cross-sectional in analyses that do not harness the power of longitudinal data. The broad goal of this article is to encourage the rigorous application of longitudinal statistical methods to human growth research.

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.