Long-term changes in daily step count goals following the introduction of a gamified smartphone application in Japan

Incentive-based strategies are widely used to promote physical activity. However, behavioural responses around predefined targets and their long-term persistence remain insufficiently understood. The aim of this study was to examine changes in daily step count distributions following the introduction of a non-financial incentive and their persistence over long-term application use.

This observational study used large-scale data from users of Pa-League Walk, a baseball fandom-based gamified smartphone application in Japan. Daily step-count data from March 2016 to December 2022 were analysed. A non-financial incentive in the form of a digital player photo reward for achieving 10,000 steps per day was introduced in October 2016. Changes in the proportion of days achieving the 10,000-step goal and daily step count distributions were examined using bunching estimation. Analyses were conducted according to application use duration (<1 year to ≥6 years).

Among 49,008 users with 11,129,438 daily observations, excess mass at the 10,000-step threshold was not significant prior to the introduction of the incentive. However, a clear accumulation of observations around the threshold emerged after the incentive was introduced. Additionally, the proportion of days achieving the 10,000-step goal increased. These distributional features persisted across application usage durations and were sustained for more than six years among long-term users.

In a gamified smartphone application, the introduction of a non-financial, repeated incentive was associated with sustained behavioural adjustments toward a predefined step-count target. These findings suggest that well-designed non-financial incentives may support long-term physical activity behaviours in a subset of users.