Associations of low-grade inflammation with physical activity, fitness and fatness in prepubertal children; the European Youth Heart Study

Early life origins of low-grade inflammation and atherosclerosis risk in children and adolescents

OBJECTIVE

To examine the relationship between birth weight and later low-grade inflammation in children and adolescents.

STUDY DESIGN

We selected 166 children (49.4% boys; aged, 9.5 +/- 0.3 years) and 126 adolescents (43.7% males; aged, 15.5 +/- 0.4 years) from the Swedish part of the European Youth Heart Study. Birth weight data were collected from parental recall. Low-grade inflammatory markers include C-reactive protein, fibrinogen, and complement factors C3 and C4. Fatness was measured by the sum of 5 skinfold thicknesses. Cardiorespiratory fitness was measured with a maximal ergometer bike test. The association between birth weight and low-grade inflammatory markers was examined with multiple regression analyses.

RESULTS

Birth weight was negatively associated with fibrinogen (beta = -0.059; P = .036), C3 (beta = -0.019; P = .010), and C4 (beta = -0.024; P = .031), after controlling for sex, pubertal status, mother's body mass index and socioeconomic status, fatness and fitness. Birth weight was not associated to later C-reactive protein level (all P > .1).

CONCLUSIONS

Our results showed that smaller birth weight is associated with chronic low-grade inflammation in children and adolescents. Because of the implication of complement factors on atherosclerosis process, these results contribute to explain the increased cardiovascular risk associated with low birth weight.

Paediatric obesity, physical activity and the musculoskeletal system

The current epidemic of paediatric obesity is consistent with a myriad of health-related comorbid conditions. Despite the higher prevalence of orthopaedic conditions in overweight children, a paucity of published research has considered the influence of these conditions on the ability to undertake physical activity. As physical activity participation is directly related to improvements in physical fitness, skeletal health and metabolic conditions, higher levels of physical activity are encouraged, and exercise is commonly prescribed in the treatment and management of childhood obesity. However, research has not correlated orthopaedic conditions, including the increased joint pain and discomfort that is commonly reported by overweight children, with decreases in physical activity. Research has confirmed that overweight children typically display a slower, more tentative walking pattern with increased forces to the hip, knee and ankle during 'normal' gait. This research, combined with anthropometric data indicating a higher prevalence of musculoskeletal malalignment in overweight children, suggests that such individuals are poorly equipped to undertake certain forms of physical activity. Concomitant increases in obesity and decreases in physical activity level strongly support the need to better understand the musculoskeletal factors associated with the performance of motor tasks by overweight and obese children.

Association of common variants of UCP2 gene with low-grade inflammation in Swedish children and adolescents; the European Youth Heart Study

We examined the associations of two functional variants 866G>A and DEL/INS polymorphisms of UCP2 gene with low-grade inflammatory proteins (C-reactive protein, fibrinogen, complement C3 [C3], and complement C4 [C4]) in 131 children (52.7% boys, aged 9.5 +/- 0.4 y) and 118 adolescents (44.1% males, aged 15.5 +/- 0.4 y) selected from the European Youth Heart Study. Differences in inflammatory markers among the genotype variants of the two UCP2 gene polymorphisms were analyzed after adjusting for sex, age, pubertal stage, fitness, and fatness. The results showed that fibrinogen, C3, and C4 were higher in GG carriers than in subjects carrying the A allele of the 866G>A polymorphism of the UCP2 gene (UCP2 -866G>A) polymorphism (all p < 0.05). The DEL/DEL genotype of 45nt deletion/insertion variant polymorphism of the UCP2 gene (UCP2 DEL/INS) was associated with higher C3 (p < 0.05) than DEL/INS and INS/INS genotypes. This study provides evidence of a role of UCP2 -866G>A in modifying low-grade inflammatory state in apparently healthy children and adolescents. Given the implication of complement factors on atherosclerosis process, these results contribute to explain the reduced cardiovascular risk associated with the A allele of the UCP2 -866G>A polymorphism.

Criterion-related validity of the one-mile run/walk test in children aged 8-17 years

We assessed the criterion-related validity of Cureton's equation for estimating peak oxygen consumption (VO(2peak)) from the one-mile run/walk test in endurance-trained children aged 8-17 years. Altogether, 66 physically active white children and adolescents (32 girls, 34 boys) completed a graded exercise test to volitional exhaustion and the one-mile run/walk test. Cureton's equation was used to estimate VO(2peak), and was assessed using several error measures. Agreement between measured VO(2peak) and estimated VO(2peak) was analysed by the Bland and Altman method. The correlation coefficient between measured VO(2peak) and one-mile run/walk time was -0.59 (P < 0.001) and that between measured and estimated VO(2peak) was 0.70 (P < 0.001). The mean difference between measured and estimated VO(2peak) was 10 ml . kg(-1) . min(-1) (95% CI = 9.2-11.8; P < 0.001). The standard error of the estimate was 3 ml . kg(-1) . min(-1), and the percentage error was 32%. There was a positive association between the measured and estimated VO(2peak) difference and the measured and estimated VO(2peak) mean, which indicates that the higher the VO(2peak) the higher the error of the estimate. These findings did not change markedly when the analyses were performed by sex, age group or body mass status. These results suggest that Cureton's equation systematically underestimates VO(2peak) in endurance-trained children with high VO(2peak).

Truncal and abdominal fat as determinants of high triglycerides and low HDL-cholesterol in adolescents

We examined whether abdominal and truncal adiposity, assessed with simple anthropometric indices, determines serum triglycerides and high-density lipoprotein (HDL)-cholesterol levels independently of total adiposity amount in adolescents. A total of 547 Spanish adolescents (284 males and 263 females) aged 13-18.5 years were included in this study. Measures of truncal adiposity included subscapular to triceps ratio, and trunk-to-total skinfolds ratio (TTS%). Waist circumference was used as a surrogate of abdominal adiposity, and BMI was used as a measure of total adiposity. The results of the regression models indicated that levels of triglycerides were positively associated with waist circumference and TTS% after controlling for age and Tanner stage in both sexes. Once BMI was entered in the model, these associations remained significant for waist circumference in females. HDL-cholesterol levels were negatively associated with waist circumference in both sexes, and with subscapular to triceps ratio and TTS% in males, after controlling for age and Tanner stage. Once BMI was entered in the model, these associations remained significant for subscapular to triceps ratio and for TTS% in males. The results of this study suggest that in male adolescents, truncal adiposity is negatively associated with levels of HDL-cholesterol, whereas in females, abdominal adiposity is positively associated with levels of triglycerides independently of total adiposity. These findings highlight the deleterious effect of both truncal and abdominal fat depots on the lipid profile already from the first decades of life.

Low-grade inflammation and the metabolic syndrome in children and adolescents

PURPOSE OF REVIEW

The prevalence of overweight and the metabolic syndrome is increasing in young people. This review aims to summarize current research in children and adolescents on inflammatory markers related to components of the metabolic syndrome.

RECENT FINDINGS

Obesity is characterized by a state of low-grade inflammation at all ages. Body fat has been shown to correlate with the various components of the metabolic syndrome. There is evidence to show that chronic subclinical inflammation in childhood and adolescence is associated with metabolic dysfunction, which can lead to insulin resistance and the metabolic syndrome.

SUMMARY

The results presented in this review highlight the underlying inflammatory mechanisms of the early stages of metabolic disorders related to obesity. The preclinical phases of diabetes and cardiovascular disease last many decades, and this feature of the diseases provides an opportunity for the early identification of target groups and the use of appropriate prevention strategies while the pathological processes are still completely reversible.

Physical fitness in childhood and adolescence: a powerful marker of health

This review aims to summarize the latest developments with regard to physical fitness and several health outcomes in young people. The literature reviewed suggests that (1) cardiorespiratory fitness levels are associated with total and abdominal adiposity; (2) both cardiorespiratory and muscular fitness are shown to be associated with established and emerging cardiovascular disease risk factors; (3) improvements in muscular fitness and speed/agility, rather than cardiorespiratory fitness, seem to have a positive effect on skeletal health; (4) both cardiorespiratory and muscular fitness enhancements are recommended in pediatric cancer patients/survivors in order to attenuate fatigue and improve their quality of life; and (5) improvements in cardiorespiratory fitness have positive effects on depression, anxiety, mood status and self-esteem, and seem also to be associated with a higher academic performance. In conclusion, health promotion policies and physical activity programs should be designed to improve cardiorespiratory fitness, but also two other physical fitness components such us muscular fitness and speed/agility. Schools may play an important role by identifying children with low physical fitness and by promoting positive health behaviors such as encouraging children to be active, with special emphasis on the intensity of the activity.