Exercise as it relates to Disease/Reducing obesity in children by adjusting TV viewing habits

This fact sheet is a critical response to the article Decreasing Sedentary Behaviors in Treating Pediatric Obesity by Leonard H. Epstein, PhD; Rocco A. Paluch, MA; Constance C. Gordy, MS; Joan Dorn. PhD

What is the background to this research?

Sedentary behaviour, typically defined as activities requiring low levels of energy expenditure (EE) that occur while sitting or lying down, has been the subject of increasing epidemiological research in recent years.. Emerging evidence indicates that various markers of sedentary behaviour, including TV viewing and total sitting time, are closely associated with chronic disease morbidity and mortality, often independent of physical activity. Television watching has been prospectively related to childhood adiposity in several epidemiological studies. Watching television, among with other sedentary behaviours may contribute to obesity by competing with time spent on more physically active behaviours, as well as setting the scene for eating. Parent-report and self-report data from a nationally representative sample of 3155 children indicate that 2- to 7-year-old children in the United States spend an average of approximately 2.5 hours per day and 8- to 18-year-old children spend an average of about 4.5 hours per day watching television and videotapes and playing video games.

Where is this research from?

This research was conducted by the Departments of Psychology and Social and Preventive Medicine, University at Buffalo and the State University of New York and was undertaken in a childhood obesity research clinic. The effect of reducing television viewing and other sedentary behaviour as an aspect of an obesity treatment program had not been widely tested in the past; however this study was undertaken in March 2000 so it is very likely that more research has developed since then. Given that the study was carried out cohesively by three separate institutions, it is fair to believe that bias and/or conflicts of interest would have been ruled out.

What kind of research was this?

The research was a quantitative randomized control trial with four experimental groups (Low exercise, high exercise, low sedentary, high sedentary).

What did the research involve?

The objective of this research was to compare the influence of targeting decreases in sedentary behaviour vs. increases in physical activity in the comprehensive treatment of obesity in 8-12 year old children. The design of this study involved 90 families with obese 8-12 year olds who were randomly assigned to one of four groups and provided with a family-based behavioural weight control program that included dietary and behaviour change information. The four groups differed in whether sedentary behaviour or physically active behaviours were targeted and the degree of behaviour change required. Of the 461 families that expressed interest; 171 were screened; and 90 were then chosen, stratified by sex and then randomly assigned to a group.

About the participants

Certain participant criteria was required in order for this study to be carried out. These included:

• Child to be between 20-100% overweight
• Neither parent 100% overweight
• At least one parent willing to attend treatment meetings
• No family member participating in an alternate weight control program
• No parent or child with current psychiatric problems
• No dietary or exercise restrictions for the parent or child

Methodology

The treatment was assigned for a 6 month period followed by a 12 and 24 month follow-up. Families received parent and child workbooks, which included introduction to weight control and self-monitoring, the Traffic Light Diet, the specific activity program of their assigned group, behaviour change techniques, and maintenance of behaviour change. The treatment included 16 weekly meetings followed by 2 biweekly and 2 monthly meetings. At these meetings, participating family members were weighed, they met with an individual therapist for 15-30 minutes and they attended separate parent and child group meetings. The main purpose for this study was to provide another test proving that decreasing sedentary behaviour produces equal or better weight loss and fitness change than increasing physical activity when included as part of a comprehensive paediatric obesity intervention.

What were the basic results?

Overall, results during the 2 years showed that targeting either decreased sedentary behaviours or increased physical activity was associated with significant decreases in percent overweight and body fat and improved aerobic fitness. Self-reported activity minutes increased and targeted sedentary time decreased during treatment. Children did however substitute nontargeted sedentary behaviours for some of their targeted sedentary behaviours.

Results of this study are similar to that of previous studies. The influence of targeting a decrease in sedentary behaviour on percent overweight decrease at 1 year was similar (-26.2%- to the current study (-24.4%), but the effect for increasing physical activity was considerably lower in the previous study when compared with the current study (-10.1% vs -20.2%).

What conclusions can we take from this research?

Research that occurs within the lab is more likely to prove that reducing sedentary behaviour is associated with increasing physical activity. . However clinical research, such as this article, shows that obese children targeted for reducing sedentary behaviour have better weight loss at 1 year than children targeted for being more physically active. Hence, stressing the importance that the change doesn't necessarily require higher amounts of physical activity, it may just be the need to reduce the amounts of sedentary behaviour. In saying that, the two approaches within this study (decrease sedentary behaviour or increased physical activity) did present similar decreases in percent overweight and increases in fitness during the 2 years of observation.

This research also mentions that children may have reduced targeted sedentary behaviours, however nontargeted sedentary behaviours increased. Children without access to enjoyable physical activities may not increase their activity when sedentary behaviours are decreased, but rather switch to other sedentary behaviours. Physical activity doesn't have to be a chore and this study aims to stress the importance of physical activity being enjoyable and engaging for children. This point is further supported by James Sallis' article that assesses perceived physical environments and factors that may influence a person's willingness to participate in physical activity.

Limitations to the study

There were a number of limitations observed when analysing this study. Some were mentioned by the author and some just sprung to mind whilst reading. First and foremost, as mentioned in the article, not all sedentary activities were targeted in this study. This study primarily looked at the effect of reducing television watching, meaning that not all sedentary behaviour was accounted for. By only focusing on one aspect of sedentary behaviour, it is difficult to state that sedentary behaviour as a whole effects childhood obesity.

Another point mentioned was having more knowledge and research into the type and pattern of sedentary behaviour in children. Understanding the pattern of changes in active behaviour and allocation of time to sedentary behaviours may be limited by self-report, and objective measurement of allocation of time to active and sedentary alternatives would provide better information on how children make choices to shift from being sedentary to becoming physically active.

Finally, the study identified that there are no large population-based samples to evaluate changes in body fat during development to better understand changes in relationship to normative data, which are available for BMI.

Other limitations to the study as picked up whilst reading include:

• Large variation in parent weight (standard deviation over 25%) and therefore habits;
• Percent overweight brackets for both parent and child should be smaller - too much variation in participants;
• Reliability of participants in a self-report study - especially as the participants in this study are children;
• Natural human error when recording results

Practical advice

Reducing sedentary behaviour is associated with similar weight, fitness and psychological changes in comparison to a well-validated program to increase physical activity in children. Keeping children actively engaged in physical activity by making it fun and enjoyable, and ensuring that they don't replace one form of sedentary behaviour with another is crucial. Remember, sedentary behaviour comes in many forms, and just because they are reducing their tv viewing time may not mean that they are reducing overall time spent partaking in sedentary activities. Intermittent breaks to sedentary time is also extremely beneficial to reducing the risk of health related disease.