Background: Using the multiphase optimization strategy (MOST) framework, we aimed to identify an optimized mHealth-delivered intervention for reducing recreational sedentary screen time (rSST) by at least 60 min/day among adults.

Methods: Eligible participants were 23-64 years old and self-reported elevated rSST (> 3 h/day). Following a 7-day baseline, participants received a core mHealth application (self-monitoring and 50% reduction target and educational materials) and were randomly assigned to three additional components set to on/off in a full-factorial (2³) experiment: LOCKOUT: rSST electronically restricted; TEXT: rSST reduction prompts; and EARN: rSST through physical activity. rSST was assessed at baseline and 16 weeks via an integrated measure that included objectively assessed sedentary time (activPAL accelerometer) and screen time (TV Wifi plugs and tablet usage). We used a linear mixed effect model to evaluate the change in rSST for the three intervention components and their interactions.

Results: A total of 82% of the randomized participants (N = 110) were female, with a mean ± SD age of 41 ± 11.7 y and a BMI of 29.7 ± 7.8 kg/m2, and their mean (95% CI) rSST was 184.7 (172.8, 196.5) min/day at baseline. The expected difference (baseline vs. 16 weeks) in rSST was greatest for the intervention versions with the core plus EARN on with an average reduction of -118.1 (-163.0, -73.1) min/day and for core plus LOCKOUT, TEXT, & EARN on (-125.7 [-172.0, -79.3] min/day).

Conclusions: We identified several promising intervention versions that exceeded our optimization objective. This study provides important evidence on efficacious multicomponent interventions that should be moved forward to the evaluation phase of the MOST framework to test the effect of rSST reductions on health outcomes.

Trial registration: (clinicaltrials.gov NCT04464993).

Keywords: Multiphase optimization trial; Physical activity; Screen time; Sedentary behavior; Television viewing; mHealth application.

© 2025. The Author(s).

背景: 使用多阶段优化策略（MOST）框架，我们的目标是识别一种通过移动健康应用程序递送的干预措施，以减少成年人每天至少60分钟的休闲久坐屏幕时间（rSST）。

方法: 符合条件的研究参与者年龄在23至64岁之间，并且自我报告的休闲久坐屏幕时间超过3小时/天。研究对象完成7天基线期后，接受核心移动健康应用程序（自我监测、50%减少目标及教育材料），然后被随机分配到三个附加组件之一，在全因子实验中设置为开启或关闭：锁定功能：限制rSST；短信提醒：减少rSST的提示；和赚取模式：通过体育活动抵消rSST。在基线期和16周时，通过包括客观评估久坐时间（activPAL加速度计）和屏幕时间（电视Wi-Fi插头和平板电脑使用情况）在内的综合测量方法对rSST进行评估。我们采用线性混合效应模型来评估三种干预措施及其相互作用下rSST的变化。

结果: 随机分配的参与者中，82%（N=110人）为女性，平均年龄±标准差为41 ± 11.7岁，BMI为29.7 ± 7.8 kg/m²。他们的基线rSST平均值（95％CI）为每天184.7 (172.8, 196.5)分钟。干预版本中预期的差异（基线与16周之间），核心应用程序加赚取模式开启时，平均减少-118.1 (-163.0, -73.1) 分钟/天；核心应用程序加锁定功能、短信提醒及赚取模式全开时，平均减少-125.7 [-172.0, -79.3]分钟/天。

结论: 我们确定了几种超出优化目标的有前景的干预版本。本研究提供了关于有效的多组件干预措施的重要证据，这些干预措施应推进到MOST框架的评估阶段，以测试rSST减少对健康结果的影响。

试验注册: （clinicaltrials.gov NCT04464993）。

关键词: 多阶段优化试验；体育活动；屏幕时间；久坐行为；电视观看；移动健康应用程序。

© 2025. 作者保留所有权利。