Cardiometabolic Risk in Adolescents: Associations with Physical Activity, Fitness, and Sleep—In Response to Kawada

Seasonal variability of the vitamin D effect on physical fitness in adolescents

Studies investigating the relationship between vitamin D and physical fitness in youth have provided inconsistent findings. Recent evidence indicates that the expression of receptors and vitamin D-modulated genes in young subjects has a seasonal profile. Therefore, we investigated the role of vitamin D on physical fitness across seasons in a total of 977 male adolescents. Anthropometrics, lifestyle, dietary habits, biochemical profiles and physical fitness were studied. Multiple linear regression models, including pairwise interaction terms involving total 25-OH-vitamin D, were fitted. The interacting effect of season and total 25-OH-vitamin D had a significant influence on physical fitness performance (spring and total 25-OH-vitamin D: ß 0.19, SE 0.07, p = 0.007; summer and total 25-OH-vitamin D: ß 0.10, SE 0.06, p = 0.11; autumn and total 25-OH-vitamin D: ß 0.18, SE 0.07, p = 0.01), whereas the main effect of total 25-OH-vitamin D alone was not significant (p = 0.30). Body fat percentage, recreational physical activity level, time spent per day gaming/TV-watching, smoking, and hemoglobin levels were also related to the physical fitness performance score. Future studies should further explore the role of seasonal-dependent effects of vitamin D on health.

Association between sleep duration and high blood pressure in adolescents: a systematic review and meta-analysis

CONTEXT

Sleep has been assessed as a risk factor for health consequences. Among adults, excessively longer and shorter sleep durations are associated with high blood pressure (BP), but knowledge of the association between sleep duration and high BP among adolescents is limited.

OBJECTIVES

To estimate the associations between sleep duration and high BP in adolescents.

METHODS

PubMed, Web of Science, and Cochrane databases were searched for eligible publications up until 20 November 2017. This study reviewed the reference lists from retrieved articles to search for relevant studies. Pooled odds ratios (ORs) were calculated using a random-effects meta-analysis. Sub-group and sensitivity analyses were conducted to identify heterogeneity. Publication bias was evaluated using Egger's test.

RESULTS

Seven studies involving 21,150 participants were included, with ages ranging from 10-18 years. For primary analysis, compared with the reference sleep duration, the pooled OR for high BP was 1.51 (95% confidence interval [CI] = 1.04-2.19) for the short sleep duration overall. For long sleep duration, the pooled OR was 1.04 (95% CI = 0.78-1.38). Further sub-group analysis showed that short sleep duration had a higher risk of incident high BP in males (OR = 1.55, 95% CI = 1.24-1.93) than in females (OR = 1.23, 95% CI = 0.47-3.22).

CONCLUSIONS

Among adolescents, and particularly male adolescents, short sleep duration may be a risk factor for high BP. More attention should be given to this lifestyle factor.

Associations between TV viewing, sitting time, physical activity and insomnia among 100,839 Brazilian adolescents

Our aim was to examine the relationship between insomnia and levels of physical activity (PA) and time spent sitting and TV viewing among Brazilian adolescents. Data from the Brazilian Scholar Health Survey, a nationally representative survey of 9th grade adolescents [mean: 14.28 years (range: 11-18 years)] conducted in 2015 (n = 100,839) were used. Self-reported insomnia, TV viewing, sitting time and total PA (adapted International PA Questionnaire) were collected. Chronological age, race, type of city (capital or interior) country region, goodies ingestion and ultra-processed foods ingestion were covariates. Logistic regression analyses were conducted to assess the associations. A higher sitting time and TV viewing (≥8 h/day) was associated with a higher risk of insomnia among boys [sitting time: OR = 2.39 (95%CI = 1.88-3.04); TV:OR = 2.49(95%CI = 1.92-3.22) and girls [sitting time: OR = 2.17(95%CI = 1.84-2.57; TV:OR = 1.72(95%CI = 1.44-2.04)]. More than 4 h of sitting time per day was associated with higher risk of insomnia in adolescents who comply [boys: OR = 1.43(95%CI = 1.19-1.73); girls: OR = 1.66(95%CI = 1.41-1.94)] and who do not comply with the 300 min/week of physical activity recommendation [boys = OR = 1.35(95%CI = 1.13-1.60); girls: OR = 1.38(95%CI = 1.20-1.57)]. Our data suggest that higher levels of TV viewing or sitting are associated with sleep difficulties in this large cohort of adolescents, irrespective of their physical activity behavior.

Cardiometabolic risk is associated with the severity of sleep-disordered breathing in children with obesity

BACKGROUND

The alarming progression of pediatric obesity is associated with the development of sleep-disordered breathing (SDB), and both exhibit similar adverse cardiometabolic health outcomes. Physical activity level (PAL) may counteract sleep and metabolic disturbances. The present study investigates i) the association between the metabolic syndrome in childhood obesity and SDB, ii) the impact of SDB severity on cardiometabolic risk scores and PAL in children with obesity.

METHODS

Maturation status (Tanner stages), anthropometric (height, weight, body mass index, waist circumference, body adiposity index) and cardiometabolic characteristics (systolic and diastolic blood pressure, lipid and glycemic profiles) were assessed in 83 obese children (mean±SD, age: 10.7±2.7years). PAL and SDB were investigated with a step test and interviews, and an overnight sleep monitor, respectively. The presence or absence of metabolic syndrome (MS) was established and continuous cardiometabolic risk scores were calculated (MetScore_BMI and MetScore_WC).

RESULTS

Obese children with (61.4%) and without (38.6%) MS present similar SDB. SDB severity is associated with increased insulin concentrations, MetScore_BMI and MetScore_WC (p<0.05) in obese children. There is no association between SDB and PAL.

CONCLUSIONS

In a context where no consensus exists for SDB diagnosis in children, our results suggest the influence of SDB severity on cardiometabolic risk factors. Further studies are needed to explore the association between PAL and both metabolic and sleep alterations in obese children.