Original research
Screen time, cardiorespiratory fitness and adiposity among school-age children from Monteria, Colombia

https://doi.org/10.1016/j.jsams.2013.09.010Get rights and content

Abstract

Objectives

To explore the association between electronic media exposure (television viewing time, personal computer/video game use, total screen time), and waist circumference and body mass index, and study whether this association is independent of cardiorespiratory fitness, in a representative sample of adolescents from Montería, Colombia.

Design

Cross-sectional study analyzing data from 546 students aged 11–18 years, from fourteen randomly selected schools. Z-scores for WC and BMI were calculated.

Methods

The physical activity module of the Global School Health Survey 2007 was used to determine EME, and the shuttle run test was used to assess CRF. Linear regression models adjusted by age, school location, physical activity level, type of institution (public or private), consumption of sweetened beverages, fast food, and fried food were used.

Results

Among boys, independently of cardiorespiratory fitness, high television viewing time (≥2 h/day) (β = +0.22; p < 0.02), was positively associated with waist circumference. High total screen time (>3 h/day) was positively associated with waist circumference (β = +0.34; p < 0.01), and body mass index (β = +0.39; p < 0.01). Among girls, sedentary behavior was not associated with adiposity, but cardiorespiratory fitness (β = −0.04; p < 0.02) was negatively associated with body mass index.

Conclusions

These findings support the evidence on the negative impact of excessive electronic media exposure and low cardiorespiratory fitness, and highlight the need for interventions and prevention strategies.

Introduction

Excess adiposity, particularly visceral adipose tissue, is associated with increased risk of chronic diseases.1 Recent estimates indicate that the prevalence of overweight among adolescents has increased markedly in developing countries.2 For instance, in Brazil the prevalence of overweight increased from 3.7% in 1974 to 21.7% in 2009, among boys 10–19 years of age, while among girls overweight increased from 7.6% to 19.4%.3 In Colombia, rates of overweight among adolescents increased from 13.7% in 2005 to 16.7% in 2010, and this growth was higher among boys.4 Considering the negative health impacts of obesity, the trend toward excess adiposity among school-age children is a public health concern.

Rapid processes of urbanization and globalization have been linked with increased obesity in low and middle income countries.5 In this context, changing diets, decline in physical activity (PA) levels and increased sedentary behaviors have all contribute to a higher prevalence of obesity.6 In addition, sitting for prolonged periods of time plays a significant role in the development of obesity,7 and according to recent evidence, it could be considered, along with poor fitness, a modifiable risk factor for cardiovascular and metabolic disease.8 Most of the sedentary behavior (SB) is characterized by what is called electronic media exposure (EME), this is the access and use of electronic devices, such as television, computers, cell phones, and video games. Access and use of these devices is growing around the world.8

Previous studies in youth have shown consistent associations between SB and excess adipose tissue, explained through various mechanisms such as increased energy intake,9 reduced metabolic rate,10 and lower levels of PA.11 The mechanism by which sedentary behavior is associated with low cardiorespiratory fitness may be, presumably, due to displacement of time spent in PA.12 Previous studies have suggested a mechanism by which cardiorespiratory fitness (CRF) attenuates the health risk of obesity, and may even mitigate the effects of sedentary behavior.12 Studies have also documented that EME patterns are established early in life, and track through adulthood.13 However, available evidence of associations between SB with adiposity, independently of CRF, are more limited.

Despite acknowledgment of the importance of studying and tracking sedentary behaviors for public health surveillance, few studies have examined associations of EME with central adiposity and BMI among school-age children living in deprived areas of Latin America. Therefore the aim of this study is to explore the association between EME, Total Screen Time (TST), and WC and BMI, and whether this association is independent of CRF, in a representative sample of adolescents from Montería, Colombia.

Section snippets

Methods

The current study was conducted between June and September 2008 in Montería, capital city of Cordoba, located in the Caribbean coast of Colombia which has a population of approximately 382,000 inhabitants. Since 1995, there has been a rapid increase in the population partly explained by the large number of displaced families and individuals that migrate into the city escaping from the violence generated in the countryside as a result of internal conflict.14 By 2005, there were more than 20,800

Results

The descriptive characteristics of the study sample are shown in Table 1. The average age for participants was 14.4. The sample included almost an equal number of boys (n = 278, 55.6%) and girls (n = 268). Boys were taller (t = 5.7; p < .005), and had higher VO2max (t = 8.8, p < .001) than girls. Girls had a higher BMI (t = −0.67, p < .05) than boys. Boys reported more frequency (times/day) of consumption of high fat foods compared to girls (t = −2.4, p < .05). A total of 135 (21%) adolescents were classified as

Discussion

In this study it was found that over half of the sample reported TV viewing ≥2 h/day and TST ≥3 h/day, and approximately 80% of the adolescents are physically active. These prevalence estimates indicate that most adolescents in our sample are exposed to conditions that have been linked to cardiovascular and metabolic risk.24 It was detected that excessive EME (TV viewing ≥2 h/day and TST >3 h/day), was independently and directly related to WC in boys. Similarly, TST >3 h/day was significantly and

Conclusions

In conclusion, our study provides evidence of significant associations between EME and markers of adiposity including WC and BMI independently of CRF among boys. This finding suggests that levels of EME should be considered when trying to understand the factors associated with central adiposity, and for obesity prevention initiatives. Our findings of no association between any of the EME indicators and adiposity among girls, as well as similar findings from other studies, highlight the fact

Practical implications

  • •

    Excessive electronic media exposure may play an important role in excess adiposity, independently of cardiorespiratory fitness in Colombian boys.

  • •

    Overweight prevention programs should begin early in life and include strategies to reduce sedentary behavior, increase physical activity and cardiorespiratory fitness.

  • •

    Interventions aimed at curbing obesity in Colombian youth may need to consider gender specific strategies.

Acknowledgments

Authors are grateful to the students and directors of participating schools. We thank the faculty and students from the Physical Education Department of the University of Cordoba, Colombia. The study was conducted with no external financial support. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention. We would like to thank Dr. Amy Eyler for her valuable comments in earlier versions of

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