Challenging Dogma - Fall 2007

...Using the social and behavioral sciences to improve the practice of public health.

Tuesday, December 11, 2007

Physical Activity Recommendations in an Obese America: Too Vague, Too Aggressive, Too Bad –Tyler Aiken

One of the most alarming trends in America is the growing rate of childhood obesity. From 1988-2006 there has been an average 7% increase in the prevalence of overweight children ranging from two to nineteen years of age(1). The obesity trend will affect future generations. It puts our nation’s youth at a higher risk for developing early onset chronic diseases like diabetes and cardiovascular disease (2,3) . Today’s society is a more health conscious America then it was 50 years ago, yet there are unseen factors that are changing the body composition of our children. According to The Centers for Disease Control and Prevention, behavioral, environmental, and genetic factors are leading to the growing obesity epidemic (1). This is not the most accurate frame to portray the issue because there is an unequal contribution by each of these factors. Obesity does have a genetic component, but the gene pool does not change that drastically in a 30 year period (4). Removing genetics from the equation, it is concluded that the obesity trend is a direct result of both behavioral and environmental changes. It is therefore most beneficial if we create interventions that target these underlying causes.

Increasing physical activity in our daily lives is one possible way of combating the growing obesity epidemic (5). The 2005 Dietary Guidelines for Americans indicate that children and adolescents should engage in at least 60-minutes of physical activity on most, preferably all, days of the week(6). The 60-minute duration was based on multiple studies looking at duration of activity on physical and clinical health outcomes. Science supports the fact that 60-minutes of physical activity will benefit health outcomes (7), yet despite this knowledge there is still an increase in childhood obesity. The national 60-minute physical activity recommendation is an ineffective intervention against childhood obesity because it does not consider the total external factors, self-efficacy, and readiness to change of its target population.

Diverse Exposure to External Factors

The 60-minute physical activity recommendation fails because it does not account for the diversity in exposures to external factors. External factors are defined as any influence outside of ones internal thoughts, self perceptions, and beliefs (8). A person’s beliefs and actions are shaped by where they live, their social network, and by past experiences. Social Cognitive Theory explains how these social and environmental factors impact thoughts and decisions. Socioeconomic status (SES) and geographical environment have an important role in the effectiveness of a physical activity recommendation. These two factors highlight the issue of opportunity. The problem with the physical activity recommendations are they assume that everyone has the same access to facilities and programs that help promote physical activity. It has been shown that adolescents living in areas with less transportation, less recreation areas, and high crime rates had significantly lower physical activity levels when compared to their counterparts(9). Children of high income families have also been shown to exhibit higher levels of physical activity (10). It is made apparent that children face a wide range of barriers in regards to physical activity, and that making a broad-based recommendation will not fit every at risk population.

The physical activity of a child’s social network also affects the child’s physical activity outcomes. Social Cognitive Theory refers to this as “modeling” or “vicarious learning”. Children are five times more likely to be physically active if both of their parents were physically active (11). Obesity is linked to physical inactivity, it is therefore important to look at the parents body composition in relation to their children’s health behaviors (2,3). Parental obesity was associated with significantly lower amounts of physical activity in their children (12). It becomes quite apparent that we cannot advise a child to increase physical activity, when arguably; the most influential people in their lives have no intention of doing the same.

Self Efficacy Not Taken into Consideration

External cues are not the only factors that these national physical activity recommendations overlook. They do not relate to the obese population on an individual level, specifically their self efficacy. Self-efficacy refers to a person’s belief in their ability to take action, in this case increasing physical activity to meet national recommendations (8). Self-efficacy plays a role in numerous health behavior theories. Its use in the Health Belief Model (HBM) and Social Cognitive Theory will be addressed in this paper. HBM theorizes that health outcomes are based on what the person perceives as their benefits and barriers in performing a specific action, and self-efficacy acts as an underlying influence to these factors. A person will be more likely to perform an action when they believe they can succeed and that their potential benefits outweigh potential barriers. Recommending 60 minutes of physical activity to an obese child is ineffective because the barriers to increasing physical activity are extremely high. For example, when left with a choice of playing their favorite video game or participating in tag outside, an obese child may say to themselves, “Tag is too strenuous and I won’t be able to keep up, so I will stay in and do something I can actually do well.” They exhibit very low self efficacy, and this self-doubt becomes their main barrier to participating in physical activity.

Self efficacy is also molded by past experiences. Social Cognitive Theory relies on the basis of reciprocal determinism. Reciprocal determinism is when a person acts based on individual factors and social and environmental cues, responds by changing a behavior, and acts again (8). Obese persons will look at their past experiences with exercise, and will decide to change a behavior based upon their internal feelings of those experiences. Recommending 60 minutes of physical activity to a child who most likely does not have the most favorable experiences with physical activity is just as effective as telling a child to go play with a dog that has bitten them in the past. Due to these previous events an obese child is going to have extremely low self-efficacy compared to a child who has succeeded in incorporating exercise into their daily lives. The discussion of self efficacy in this paper has only related to theoretical examples, yet it is also pertinent to examine supporting scientific research. Random samples of adolescents were asked both psychosocial and environment questions regarding exercise. The results showed that the obese population within that group had significantly lower physical activity levels and self efficacy toward exercise, when compared to the non-obese population (13). Low self efficacy had a direct impact on their levels of physical activity. A study conducted almost 20 years ago highlighted self-efficacy as having a direct correlation to physical activity levels, and recommended that these issues be targeted in future intervention strategies (14). The concept of creating effective interventions that target behavior have been around for decades, yet the current recommendation for 60-minutes of physical activity still does not consider an individual’s self efficacy.

Readiness to Change of Population

This campaign also fails because it assumes that all participants are ready to change their exercise behaviors. In order to effectively change and implement a new behavior, the individual needs to have at least thought of changing that behavior. In other words, this person needs to have some intent to change. A perfect example is to think how effective it would be to tell someone they need to stop smoking when they love it and have no intent to stop. It is important to target interventions based on a person’s readiness to change. Physical activity recommendations are ineffective when a person does not intend, or have the motivation and interest to change at that specific point in time. This concept relates to another health behavior model called The Transtheoretical Model (TTM). TTM states that individuals undergo health behavior changes based on their readiness to take action (8). The model is based on stages, and that persons can enter the model at any stage, and can move between stages. For example, an obese child who has never exercised nor thought about exercising would be at what the model identifies as the “precontemplation stage”. The precontemplation stage identifies persons who have not intended to change or do not know there is a problem with their current behaviors (8). Individuals in this stage benefit from educational tools that make them aware of the problem or potential problems. While another obese child who has thought about increasing exercise and intends to sign up for spring baseball would be categorized in the “preparation stage”. The preparation stage refers to a person who is prepared to change and more importantly has the intent to change in the near future (8). These persons are already familiar with the benefits and barriers to the change; all they need is an environment to facilitate how to make the adjustment. Relating these concepts to the 60-minute physical activity recommendation, you cannot expect to effectively target both these children with the same intervention when one has not even thought of exercising. By considering the previous effects of external cues, past experience, and internal self-efficacy on an obese youth it is safe to say that the majority of our obese youth population would fall into the earlier stages of TTM. This would render the broad 60-minute physical activity recommendations useless, because you are telling children how to change. Instead the emphasis should be on why it is important to increase physical activity and therefore planting the seeds of change.

The 60-minute physical activity recommendation needs to consider there target population’s stage of change in order to create a more effective intervention. The goal of the intervention should be to move the subject into the next stage of change. This can initially be done through increasing the knowledge about physical activity. It has been shown that persons known to be in the precontemplation and contemplation stages of change benefit more from educational tools about physical activity than just exposure to physical activity alone. (15) This study illustrates that fact that if you target populations in the earlier stages of TTM, with appropriate interventions like education tools to increase awareness, there can be a higher chance of stage progression. The experiment group in this previous study was not given any specific exercise routines or durations, they were just given general information and were encouraged through that information to increase physical activity. Specifically recommending 60-minutes of physical activity time is not the most appropriate means of changing precontemplation adolescents’ exercise behavior.

Concluding Remarks

The issues presented today all come back to one central theme: there is a growing childhood obesity epidemic and the current recommendations for physical activity are an ineffective means to elicit a change in behavior. It has been shown that obese children are at higher risk for adult obesity(16), and that they are at a higher risk for developing hyperlipidemia, glucose intolerance, and hypertension(2,3). The health of our future population is at risk. It is crucial that policy makers not emphasize how much physical activity is needed to improve health parameters, but rather, what interventions can most effectively increase obese children’s behaviors and perceptions of preventative measures, like physical activity. Policy should rely more on treating the underlying causes of physical inactivity, specifically the social and environmental factors discussed on this paper.

In order to make this current recommendation effective it needs to rely on health behavior models. It needs to target the higher risk population and focus on behavioral change, not just the amount of exercise needed to improve health outcomes. The most effective way to re-structure this recommendation is to frame it in a different context. Do not leave the responsibility of accumulating physical activity in the hands of the children Create a mandate that all schools enact a curriculum based physical education program that emphasizes behavior change through education and physical activity. Reframe the 60-minute physical activity recommendation and use a health behavior based intervention that focuses on “how” rather then “how much”.


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