Supplementary Material for: Changes in Psychological Determinants of Behavior Change after Individual versus Group-Based Lifestyle-integrated Fall Prevention: Results from the LiFE-is-LiFE Trial

<b><i>Objective:</i></b> The Lifestyle-integrated Functional Exercise (LiFE) intervention has been shown to promote physical activity in fall-prone older adults. However, the underlying mechanisms of how LiFE functions remain unclear. This study compares the effects of the individual and group-based LiFE formats on psychological determinants of behavior change derived from the health action process approach, habit formation theory, and self-determination theory. <b><i>Methods:</i></b> Secondary analysis on basis of the randomized, non-inferiority LiFE-is-LiFE trial were performed. Questionnaire data on psychological determinants were obtained from older adults (<i>M</i> = 78.8 years, range 70–95) who took part in either the individual (<i>n</i> = 156) or the group-based (<i>n</i> = 153) LiFE intervention. Measurement points varied from three to six times, and from baseline (T1) up to a 12-month follow-up (T6). A generalized linear mixed model was specified for each determinant. <b><i>Results:</i></b> Both LiFE and gLiFE participants reported lower levels of motivational determinants at T6. LiFE participants showed significantly higher values of action planning and coping planning at T6. Participants in both formats showed increased levels of action control at T6, whereas participants’ habit strength decreased post-intervention but then stabilized over time. LiFE participants showed higher levels of autonomy, competence, and relatedness throughout the study, but levels of intrinsic motivation did not differ between formats and from T1 to T6. <b><i>Conclusion:</i></b> In both formats, but especially in the individual LiFE, the behavior change techniques used affected volitional rather than motivational or general determinants of behavior change. Habit strength as an important indicator of the sustainability of the LiFE exercises stabilized over time, indicating that participants, at least partly, sustained their formed habits long-term.

<b><i>研究目标：</i></b> 整合生活方式的功能锻炼（Lifestyle-integrated Functional Exercise，以下简称LiFE）干预已被证实可促进易跌倒老年人群的身体活动，但该干预发挥作用的潜在机制仍未明确。本研究基于健康行动过程取向理论（health action process approach）、习惯形成理论（habit formation theory）与自我决定理论（self-determination theory），对比个体式与团体式两种LiFE干预形式对行为改变心理决定因素的影响。
<b><i>研究方法：</i></b> 本研究针对随机非劣效性LiFE-is-LiFE试验开展二次分析。研究对象为参与个体式（n=156）或团体式（n=153）LiFE干预的老年人群（平均年龄M=78.8岁，年龄区间70~95岁），其心理决定因素相关问卷数据共采集3至6次，测量时点覆盖基线（T1）至12个月随访（T6）。针对各心理决定因素分别构建广义线性混合模型。
<b><i>研究结果：</i></b> 个体式LiFE与团体式LiFE（以下简称gLiFE）参与者在T6时的动机性决定因素水平均有所降低。个体式LiFE参与者在T6时的行动规划与应对规划水平显著更高。两种干预形式的参与者均在T6时表现出行动控制水平提升，而习惯强度在干预后出现下降，但随后随时间趋于稳定。整个研究周期内，个体式LiFE参与者的自主性、胜任感与归属感水平均更高，但两种干预形式间的内在动机水平无显著差异，且随T1至T6未出现明显变化。
<b><i>研究结论：</i></b> 两种干预形式所采用的行为改变技术，均可对行为改变的意志性决定因素产生影响，而非动机性或一般性决定因素，其中个体式LiFE的效果尤为突出。作为LiFE锻炼方案可持续性的重要指标，习惯强度随时间趋于稳定，表明参与者至少在一定程度上实现了所形成锻炼习惯的长期维持。