School of Education, Faculty of Education and Arts, University of Newcastle, Callaghan Campus, Callaghan, Newcastle, NSW 2308, Australia.
J Adolesc Health. 2010 Jul;47(1):83-91. doi: 10.1016/j.jadohealth.2009.12.015. Epub 2010 Feb 11.
The objective of this investigation was to examine the mechanisms of physical activity and dietary behavior change in the Program X intervention.
Program X involved a clustered randomized controlled design with six schools (N=124 participants, mean age=14.1+/-0.8 years) randomized to intervention or control conditions for the 6-month study period. Physical activity and fruit and vegetable consumption were assessed using pedometers and questionnaires, respectively. The theoretical framework of the intervention was assessed using structural equation modeling, mediation, and moderation analyses.
The model explained 56% of the variance in physical activity at 6-months, but did not represent a good fit to the data, chi(2)=87.43, df=19, p < .001. The model explaining fruit and vegetable consumption explained 31% of the variance and provided a good fit to the data, chi(2)=12.40, df=10, p=.259. None of the variables satisfied the criteria for mediation or moderation in the physical activity model, but gender moderated the effects of intervention on fruit and vegetable consumption.
None of the hypothesized mediators were responsible for behavior change in the Program X intervention. Future studies should address the limitations of existing psychosocial scales and continue to explore the mechanisms of behavior change using model testing, mediation, and moderation analyses.
本研究旨在探讨 Program X 干预中体育活动和饮食行为改变的机制。
Program X 采用了集群随机对照设计，有 6 所学校（N=124 名参与者，平均年龄=14.1+/-0.8 岁）参与，在 6 个月的研究期间随机分为干预组和对照组。通过计步器和问卷分别评估体育活动和水果及蔬菜摄入量。采用结构方程模型、中介和调节分析评估干预的理论框架。
该模型解释了 6 个月时体育活动变化的 56%，但数据拟合度不佳，卡方值=87.43，自由度=19，p<.001。解释水果和蔬菜摄入量变化的模型解释了 31%的方差，与数据拟合良好，卡方值=12.40，自由度=10，p=.259。在体育活动模型中，没有任何变量符合中介或调节的标准，但性别调节了干预对水果和蔬菜摄入的影响。
在 Program X 干预中，没有假设的中介变量负责行为改变。未来的研究应该解决现有心理社会量表的局限性，并继续使用模型测试、中介和调节分析来探索行为改变的机制。
