DRAFT: This module has unpublished changes.

Overview of Adolescent Physical Activity

Physical activity (PA) positively correlates with many health benefits, ranging from decreasing risk of chronic diseases such as cardiovascular disease or diabetes to improving emotional health and mental cognition. The more often and consistent the physical activity, the greater these health benefits.1 This is especially critical in adolescents and children, as PA tends to decrease with age.2,3 The transition period for adolescents entering into early adulthood has been shown to be a critical period in which there is a sharp decline in physical activity. In a longitudinal cohort study by Kwan et al., adolescents initially aged 12 to 15 showed an overall 24% decrease in physical activity across a period of 12 years from adolescence into adulthood.2 Further research found that over a two-year period from mid- to late adolescence, moderate-to-vigorous physical activity (MVPA) decreased significantly in both boys and girls.3


There is a strong correlation indicating that PA practiced in adolescence directly carry to adulthood. A study by Alfano et al. showed that for every 1-unit increase in adolescent PA, there was an observed 0.22 increase in adult PA;4 Gordon-Larsen et al. found that two-thirds of adolescents who performed five or more MVPA sessions weekly continued to reach this threshold as adults.5 Further research supports a consistent finding of a fairly well-established, positive association between adolescent PA and adult PA levels.3


The immediate impacts of increased PA for adolescents may include decreased body fat, decreased blood pressure and glucose levels, improved bone mass, decreased depression and/or increased self-esteem, among other emotional, mental, educational, and physical health benefits.3,6 However, recent research has investigated long-term impacts of PA in fighting off and preventing chronic disease in adulthood. Development of chronic diseases like heart disease, osteoporosis, cancer, and diabetes have been shown to be influenced by the amount of PA practiced during adolescence.3 PA has also been closely linked to obesity and maintaining body weight. Lack of adequate PA contributes to adolescent overweightness and obesity.7 It is well documented that overweight and obese adolescents have a much higher likelihood of becoming overweight or obese as adults.8 According to Herman et al., overweight youth were 6.2 times more likely to be overweight as adults, as compared to healthy weight youth. Furthermore, over 80% of overweight youth remained overweight as adults.9 It is because of these widespread impacts on health, both immediately and later in life, that studying and understanding PA behavior among adolescents is of critical importance. To begin the process of reversing the epidemic of obesity and skyrocketing prevalence of chronic disease seen globally, it is necessary to look towards the future by focusing on the world’s current youth.


The purpose of this investigation was to evaluate the efficacy of the Walking Intervention through Texting for Adolescents (WalkIT-A). This 12-week intervention builds upon behavioral theory to provide an incentive-based, adaptive intervention to inactive adolescents. The study was aimed at shaping physical activity behavior in adolescents aged 12-17 through a mobile health intervention that paired adaptive goal setting with financial incentives to increase step count. Using a single case design (N-of-1), the intervention aimed at shaping participants’ PA behavior to achieve the recommended 11,500 steps per day. PA was measured through step count and active minutes were compared to baseline levels.


Current research expands upon a previous single participant (adolescent) study and is part of a larger series clinical investigation called WalkIT or Walking Intervention through Text Messaging, conducted by Principal Investigator Dr. Marc Adams at Arizona State University. It was hypothesized that participants during the adaptive intervention phase would increase both steps per day and active minutes compared to values during their baseline phase (i.e., counterfactual). Additionally, it was hypothesized that participants would improve anthropometric measures (e.g. weight) and cardiovascular fitness (e.g. estimated VO2 peak) at 10 weeks over baseline levels.


This research directly aligns with the Grand Challenge theme of Health. Applications can be seen in both the Grand Challenges of Advancing Health Informatics and Engineering Better Medicines. There is an increasing societal shift in medicine towards prevention rather than treatment. Prevention methods are a form of “better medicines” that will work to make our society healthier and work to provide an option to shift away from many unsustainable and costly treatment methods. Showing the effectiveness of a walking intervention to help obese and overweight youth increase their physical activity will help them get healthier and potentially avoid larger health implications down the road that could lead to dangerous and costly treatments. In regards to advancement of health informatics, a method of acquiring and gathering health data in real time and through an automatically digitized platform can aid in the management, access, and use of health information worldwide.

DRAFT: This module has unpublished changes.