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BEHAVIORAL ECONOMICS: TOOLS
Physical Activity Guidelines that adults engage in 150 minutes of moderate intensity physical activity (e.g., brisk walking) and/or 75 minutes of vigorous intensity physical activity (e.g., swimming) per week. For children, 60 minutes of daily physical activity is recommended. Engaging in more physical activity will likely result in additional health benefits, based on studies finding a dose-response relationship between physical activity and morbidity and mortality prevention. For example, a cohort study that followed over 660,000 men and women for an average of 14.2 years, found a 31 percent lower risk for mortality among those engaging in physical activity at 1–2 times the recommended levels, whereas being physically active 3–4 times the recommended levels had a 37% reduced mortality risk (Arem et al., 2015).
Unfortunately, most individuals do not meet the recommended levels, let alone exceed them. According to nationally representative data in the US, only about half (49.2%) of adults meet physical activity guidelines, based upon self-report measures (Centers for Disease Control and Prevention, n.d.).
The data based on objectively measured physical activity (i.e., using accelerometers) are even more dismal, indicating that less than 5 percent of US adults meet the recommended activity levels (Troiano et al., 2008). The rate of physical activity differs markedly by age and gender, with men more active than women, and children more active than adolescents and adults.
Moreover, when examining accelerometer-determined physical activity by race/ethnicity among adults aged 20–59 years, there are differences, however, mostly in men. Specifically, among men, non-Hispanic whites on average engaged in 34.6 minutes a day of moderate to vigorous intensity physical activity (MVPA), non-Hispanic blacks engaged in an average of 37.9 minutes of MVPA daily, whereas Hispanics engaged in 45.7 minutes of MVPA on average (Troiano et al., 2008). In women, non-Hispanic whites’ engagement averaged 19.7 minutes per day of MVPA, non-Hispanic blacks averaged 20.0 minutes of MVPA daily, and Hispanics averaged 22.1 minutes of MVPA (Troiano et al., 2008). Additionally, Troiano et al. (2008) found that 42 percent of children aged 6–11 years met physical activity guidelines, as determined by accelerometers, whereas only 8 percent of adolescents aged 12–15 years and 7.6 percent of 16–19-year-olds met these guidelines.
Assessment and trends in physical activity levels
Physical activity rates have declined over the past several decades due, in large part, to increased automation and the time-saving devices at home and on the job (Ng and Popkin, 2012; Shuval et al., 2015). Occupational related activity has declined as well, as has active transportation (e.g., cycling or walking in lieu of driving), and household work (Archer et al., 2013; Ng and Popkin, 2012). Recreational physical activity, however, has remained fairly constant (Archer et al., 2013; Ng and Popkin, 2012). The energy costs of physical activity are expressed as units of metabolic equivalent of task (MET). A MET of 1 reflects a resting state while sitting; a MET of 3–5.9 represents moderate intensity activity (e.g., mowing the lawn); and a MET≥6 indicates vigorous intensity activity (e.g., swimming laps) (Ainsworth et al., 2011). To compute total energy expenditure during the week, the MET value from the various types of physical activity is multiplied by the duration and frequency of activity. For example, an individual walking for pleasure (MET=3.5), three times a week for an hour each time, will result in a total of 630 MET minutes per week (i.e., 3.5METs * 180minutes/week).
Total physical activity in the US averaged 265 MET minutes per week for adults in 1965, while only 160 MET minutes per week in 2009. Further, average weekly MET minutes were estimated to be 126 METs by 2030 (Ng and Popkin, 2012). The Physical Activity Guidelines reported above correspond to 500 MET minutes weekly; thus both past and current levels of activity are alarmingly low. In addition, nationally representative US time- use data found that women allocated ~26 hours each week to household work in 1965 compared to ~13 hours weekly in 2010, with non-employed women doing less household work than employed women (Archer et al., 2013).
Conversely, screen based media use (e.g., TV viewing) doubled during the study period from ~8 hours per week in 1965 to ~16 hours weekly in 2010 (Archer et al., 2013).
Costs of inadequate physical activity levels
Low levels of physical activity impair people’s health and directly impact medical costs. A study by Katzmarzyk et al. (2000) estimated $2.1 billion Canadian dollars were spent on medical care related to physical inactivity.
They estimated that boosting bodily activity by 10 percent would reduce medical expenditures by $150 million Canadian dollars per year. An
examination of medical claims data from Blue Cross and self-reported physical activity data from the Behavioral Risk Factor Surveillance System estimated that the insurers’ expenditures resulting from insufficient physical activity were $83.6 million US dollars, or $56 US dollars per person (Garrett et al., 2004). Additionally, individuals with high levels of cardiorespiratory fitness at midlife, a result of habitual physical activity and genetics, had reduced medical care costs at the end of life. The average annual cost of health care use was $7,569 US dollars among participants with high fitness levels, in comparison to $9,379 for patients who were moderately fit, and
$12,811 for low fit patients. Similarly, average annual costs from cardiovascular disease alone were lowest among the highly fit group, as were the number of office visits to the physician (Bachmann et al., 2015).
Economists have shown that increased physical activity is associated with higher personal earnings but the direction of causality is not entirely clear (Lechner and Sari, 2015; Maruyama and Yin, 2012). Low levels of physical activity are associated with both lower income and higher health care costs, making individuals living in low-income neighborhoods particularly vulnerable to the negative consequences of physical inactivity. Low-income households frequently live in neighborhoods least amenable to physical activity (e.g., high crime, inadequate parks, unkempt sidewalks), lack transportation and/or wealth resources to circumvent these challenges by, for example, paying for gym memberships, and are least likely to have adequate health insurance. Booth and Hawley (2015), emphasize that to avoid the
“economic death march” associated with physical inactivity and high health care costs it is paramount to implement interventions to markedly reduce the epidemic of physical inactivity.