Date Published: June 1, 2018
Publisher: Public Library of Science
Author(s): Kevin R. Short, Jennifer Q. Chadwick, Tamela K. Cannady, Dannielle E. Branam, David F. Wharton, Mary A. Tullier, David M. Thompson, Kenneth C. Copeland, Rebecca A. Krukowski.
American Indians (AI) have high prevalence of diabetes in youth and may benefit from increasing physical activity as a strategy to improve metabolic health. We tested whether financial incentives would elicit greater frequency and/or duration of exercise in AI youth at high risk for developing diabetes. Overweight/obese AI boys and girls, 11–20 years old, were instructed to exercise on 3 days/week for 48 weeks at a tribal wellness center. The program was divided into three, 16-week-long phases to test different financial incentive strategies. Within each phase participants were randomly assigned to one of two groups that received different payments for exercise. Phase 1 was designed to test whether the size of the incentive would affect exercise frequency. In Phase 1, the number of exercise sessions did not differ between the group receiving a modest fixed-value payment per exercise session and the group receiving enhanced incentives to exercise more frequently (26 ± 3 versus 28 ± 2 sessions, respectively, p = 0.568). In Phase 2, the provision of an enhanced financial incentive to increase exercise duration resulted longer sessions, as the incentivized and standard payment groups exercised 38 ± 2 versus 29 ± 1 minutes per session (p = 0.002), respectively. In Phase 3, the effect of reducing the incentives on maintenance of exercise behaviors was inconclusive due to high participant withdrawal. Aerobic fitness increased 10% during Phase 1 but was unchanged thereafter. Insulin sensitivity and body composition were unchanged during the study. In conclusion, enhanced financial incentives increased the duration of exercise sessions, but had minimal effects on exercise participation. These results indicate that financial incentives hold promise in motivating previously sedentary, overweight/obese adolescents to exercise longer, but motivating them to sustain an exercise program remains the major challenge.
The metabolic and cardiovascular health of many children in the United States is poor. Thirty percent of children in the United States are overweight or obese and fewer than half are aerobically fit or reach the recommended level of daily physical activity [1–5]. Cardiorespiratory fitness in late adolescence is a significant predictor for future cardiovascular events during adulthood . Several lines of evidence show that obesity and sedentary lifestyle elevate cardiometabolic risk early in life and set the stage for future disease in adulthood . Thus, there is a need to develop effective interventions to improve physical fitness and metabolic health in children and adolescents, especially those who are obese.
In this study, we explored whether carefully designed financial incentives could increase physical activity in previously sedentary overweight/obese, American Indian adolescents. This strategy was developed so that the targeted population would improve their health status and lower their future risk for diabetes and other cardiometabolic diseases. The program was partly successful. Most participants were initially enthusiastic about engaging in exercise and receiving payments for their efforts. Study participants collectively completed 3,229 exercise sessions and improved their aerobic fitness in Phase 1. In Phase 2, the enhanced incentive to increase the duration of exercise sessions appeared to work as hypothesized. However, the higher incentive in Phase 1 did not promote an increase in exercise frequency. Additionally, the payments did not provide a reward strong enough to sustain the exercise behavior, as demonstrated by the high rates of withdrawal from the study after the first 16 weeks. Throughout the study’s three phases, the average duration of MVPA time was ~34 minutes per exercise session, but the participants completed, on average, only half of the targeted number of three sessions per week. Thus, the participants were challenged to consistently attend the wellness center. However, once at the center, they had a high likelihood of completing a meaningful volume of exercise.
Financial incentives were modestly successful in promoting exercise behavior in previously sedentary AI adolescents at risk for diabetes. The incentives appeared to help promote the initial exercise behavior and in the study’s second phase participants responded to enhanced incentives by increasing the duration of their exercise sessions. The exercise program also resulted in an increase in aerobic fitness. However, the incentives did not promote higher exercise frequency as expected, and retention in the program was low. It remains unclear whether greater financial incentives would have resulted in even greater exercise intensity or increased frequency, or whether incentive-induced exercise behavior is sustained or reduced after such incentives are withdrawn. It is clear, however, that resistance to lifestyle change in obese, sedentary adolescents is substantial  and that novel strategies to influence exercise behavior in this group of children likely will be required.