In order to draw more concrete conclusions on the effectiveness of adaptive goal setting for increasing PA in adolescents, future studies should aim to include a stronger intervention to overcome issues observed in the current study. Secondly, the study length should be increased. Due to the short nature of the intervention, the identified trends in the data were heavily influenced by outside concurring factors, such as summer vacation and high summer temperatures. Though these types of environmental considerations are inevitable and should not be ignored, a longer study period would provide more insight into the specific impact of the intervention. Tracking steps for an entire year, for example, with multiple ABA periods (i.e. ABABABA study design) would mitigate the perceived influence of outside factors because a broader, overall picture would be more clear.
It is also interesting to note the noticeable decline in steps around days 30 to 40 compared to the beginning of the intervention. This further suggests that the intervention was not strong enough to overcome the impacts of the environment (e.g. weather or summer vacation). Furthermore, this may be evidence that the adolescents became habituated to the rewards around this midway point, indicating the need for stronger motivational components. A similar pattern was seen in adults; right around day 30-40, PA began to trend back to baseline levels. However, the adults had an overall greater adoption of PA throughout the intervention compared to the adolescents.30 One possible reason for this may be that the rate of habituation is faster for adolescents than adults. This rapid habituation may be because adolescents exhibit steeper levels of delayed discounting, as a result of overall shorter attention spans. According to Sofis, et al., individuals who discount the value of delayed rewards less steeply are more likely to engage in PA.49 The delayed discounting methodology used in WalkIT-Adolescent was adopted from the WalkIT study conducted in adults.30 In this study, a 60% threshold was found to be effective with adults, meaning that adults meeting their daily step goal 60% of the time received ample reward to perceive enough value to continue or maintain increased steps from baseline. When translated to the adolescent participants in this study, this 60% cutoff equated to the participants earning on average one $5 gift card every 13 days. As seen by the downward step trend across the intervention, it would appear that the discounting of $5, thirteen days from now, was too steep of a delayed discounting rate to evoke PA among adolescents. To account for this, the intervention may be more effective if rewards were given more quickly, decreasing the perceived delay. Additionally, it would be beneficial if right around day 30-40, the incentive became variable (i.e. different award amounts or types). Another possibility would be the introduction of an additional incentive on top of what is already being received, such as the introduction of a bonus challenge or competition. Providing an added level of novelty midway through the intervention may serve to induce greater levels of excitement and thus engagement with the intervention to combat both environmental and habitual factors leading to decreased PA.