Background Web-based interventions for multiple health behavior change (MHBC) appear to be a promising approach to change unhealthy habits. Limited research has tested this assumption in promoting physical activity (PA) and fruit-vegetable consumption (FVC) among Chinese college students. Moreover, the timing of MHBC intervention delivery and the order of components need to be addressed. Objective This study aims to examine the effectiveness of 2 sequentially delivered 8-week web-based interventions on physical activity, FVC, and health-related outcomes (BMI, depression, and quality of life) and the differences in the intervention effects between the 2 sequential delivery patterns. The study also aims to explore participants’ experiences of participating in the health program. Methods We conducted a randomized controlled trial, in which 552 eligible college students (mean 19.99, SD 1.04 years, 322/552, 58.3% female) were randomly assigned to 1 of 3 groups: PA-first group (4 weeks of PA followed by 4 weeks of FVC intervention), FVC-first group (4 weeks of FVC followed by 4 weeks of PA intervention), and a control group (8 weeks of placebo treatment unrelated to PA and FVC). The treatment content of two intervention groups was designed based on the Health Action Process Approach (HAPA) framework. A total of four web-based assessments were conducted: at baseline (T1, n=565), after 4 weeks (T2, after the first behavior intervention, n=486), after 8 weeks (T3, after the second behavior intervention, n=420), and after 12 weeks (T4, 1-month postintervention follow-up, n=348). In addition, after the completion of the entire 8-week intervention, 18 participants (mean 19.56, SD 1.04 years, 10/18, 56% female) who completed the whole program were immediately invited to attend one-to-one and face-to-face semistructured interviews. The entire study was conducted during the fall semester of 2017. Results The quantitative data supported superior effects on physical activity, FVC, and BMI in the 2 sequential intervention groups compared with the control group. There were no significant differences in physical activity, FVC, and health-related outcomes between the 2 intervention groups after 8 weeks. The FVC-first group contributed to more maintenance of FVC compared with the PA-first group after 12 weeks. Four major themes with several subthemes were identified in the qualitative thematic analysis: PA and FVC behavior, health-related outcomes, correlates of behavior change, and contamination detection. Conclusions This study provides empirical evidence for the effectiveness of sequentially delivered, web-based MHBC interventions on PA and FVC among Chinese college students. The timing issue of MHBC intervention delivery was preliminarily addressed. Qualitative findings provide an in-depth understanding and supplement the quantitative findings. Overall, this study may contribute considerably to future web-based MHBC interventions. Trial Registration ClinicalTrials.gov NCT03627949; https://clinicaltrials.gov/ct2/show/NCT03627949 International Registered Report Identifier (IRRID) RR2-10.1186/s12889-019-7438-1

BACKGROUND Web-based multiple health behavior change (MHBC) interventions have proved to be effective in promoting physical activity (PA) and increasing fruit-vegetable consumption (FVC) among Chinese college students. However, limited research has examined the intervention effects of web-based MHBC interventions on a combined healthy lifestyle (i.e., adhering to both PA and FVC behavioral recommendations) among college students. In addition, the salient psychosocial mediators of successful MHBC need to be addressed. OBJECTIVE This study aimed to examine the effectiveness of an 8-week web-based MHBC intervention on promoting a combined healthy lifestyle and increasing psychosocial determinants of behavioral change (i.e., intention, self-efficacy, planning, and social support all relating to PA and FVC). Further, the study aimed to identify whether changes in these psychosocial determinants of PA and FVC could mediate the intervention effectiveness on the combined lifestyle indicator. METHODS This study was a secondary analysis for a three-arm, double-blinded randomized controlled trial. A total of 552 Chinese college students were randomly assigned to one of three groups, including a PA-first group (4-week intervention on PA followed by 4-week on FVC), an FVC-first group (4-week intervention on FVC followed by 4-week on PA), and a control group (8-week placebo treatment irrelevant to PA or FVC). The intervention content for PA-first and FVC-first groups was designed based on the health action process approach (HAPA) model. Data for analyses was collected at baseline (T0), post-intervention test (T1; 8 weeks after T0), and follow-up test (T2; 12 weeks after T0). RESULTS At baseline, only 13.9% of participants adopted a combined healthy lifestyle. After 8 weeks, the percentage of participants with a combined healthy lifestyle increased prominently (36.2%). Participants in the PA-first and FVC-first groups were respectively 3.24 and 5 times more likely to adopt a healthy lifestyle compared to the control group at T1. After 12 weeks, a total of 35.5% of participants maintained the combined healthy lifestyle. Participants who received the web-based MHBC interventions were 2.99 (PA-first) and 4.07 (FVC-first) more likely to maintain a combined healthy lifestyle relative to the control condition at T2. Intervention effects favored both intervention groups in self-efficacy and planning for PA and in intention and planning for FVC compared to the control condition. For mediation analyses, changes in self-efficacy for PA, and intention for FVC significantly mediated the intervention effectiveness on the immediate lifestyle change after 8 weeks (T1). Changes in intention for FVC was identified as a significant mediator for facilitating sustained lifestyle change after 12 weeks (T2) among Chinese college students. CONCLUSIONS This study provides empirical evidence for the effectiveness of an 8-week theory-based and web-based MHBC intervention program on promoting a combined healthy lifestyle and several psychosocial determinants of behavioral change among Chinese college students. These research findings also add new evidence to the underlying psychosocial mechanisms of successful MHBC. Overall, this study may have considerable implications for future web-based MHBC research and practice. CLINICALTRIAL N/A. INTERNATIONAL REGISTERED REPORT RR2-10.2196/30566

Background Web-based multiple health behavior change (MHBC) interventions have demonstrated effectiveness in promoting physical activity (PA) and fruit and vegetable consumption (FVC) among Chinese college students. However, there is limited research examining their effects on promoting a healthy lifestyle (ie, adhering to both PA and FVC behavioral recommendations) among Chinese college students. In addition, the salient psychosocial mediators of successful MHBC interventions need to be researched. Objective This study aims to examine the effectiveness of a previous 8-week web-based MHBC program for promoting a healthy lifestyle and enhancing the psychosocial determinants (intention, self-efficacy, planning, and social support) of behavior change among Chinese college students. Furthermore, the study aims to identify whether changes in these psychosocial determinants mediate intervention effectiveness on the immediate and sustained lifestyle changes. Methods This was a secondary analysis for a 3-arm randomized controlled trial. Chinese college students (N=552) were randomly assigned to 1 of 3 groups: a PA-first group (4-week PA intervention followed by 4-week FVC intervention), an FVC-first group (4-week FVC intervention followed by 4-week PA intervention), and a placebo control group. The intervention content was designed based on the health action process approach model. Data for analyses were collected at baseline (T0), postintervention assessment (T1), and 12-week follow-up assessment (T2). Results At baseline, 13.9% (77/552) of the participants maintained a healthy lifestyle. After 8 weeks, more (200/552, 36.2%) participants achieved a healthy lifestyle. PA-first and FVC-first groups were, respectively, 3.24 times and 5 times more likely to adopt a healthy lifestyle than the control group at T1. After 12 weeks, 35.5% (196/552) of the participants adopted a healthy lifestyle. Intervention groups were approximately 2.99 times (PA first) and 4.07 times (FVC first) more likely to adopt a healthy lifestyle than the control group at T2. Intervention effects favored both intervention groups in self-efficacy and planning for PA and in intention and planning for FVC compared with the control condition. In addition, changes in PA self-efficacy and FVC intention mediated intervention effectiveness on the immediate lifestyle change after 8 weeks. Changes in FVC intention were identified as a salient mediator for facilitating sustained lifestyle change after 12 weeks. Conclusions This study provides empirical evidence for the effectiveness of an 8-week theory- and web-based MHBC intervention program on promoting a healthy lifestyle, self-efficacy and planning for PA, and intention and planning for FVC among Chinese college students. These research findings add new knowledge to the underlying psychosocial mechanisms of successful MHBC interventions. Overall, this study has considerable implications for future web-based MHBC research and practice in terms of addressing PA self-efficacy and FVC intention and helping students to adopt and maintain a healthy lifestyle independently of whether PA or FVC is addressed first. Trial Registration ClinicalTrials.gov NCT03627949; https://clinicaltrials.gov/ct2/show/NCT03627949

BACKGROUND Evidence indicated a high prevalence of physical inactivity and insufficient consumption of fruit and vegetables among college students. Web-based interventions for multiple health behavior change (MHBC) appears to be a promising approach to change the unhealthy habit. Limited research has tested this assumption in promoting physical activity (PA) and fruit-vegetable consumption (FVC) among Chinese college students. Moreover, the best sequential delivery mode of MHBC intervention needs to be addressed. OBJECTIVE From both quantitative and qualitative perspectives, this study aimed to examine (1) the effectiveness of two sequentially delivered 8-week web-based interventions on PA, FVC and health-related outcomes, and (2) which sequential timing is superior in behavior change. The intervention content was based on the health action process approach. Self-reported data were evaluated including PA, FVC, and health-related outcomes (Body Mass Index (BMI), depression and quality of life). METHODS In a randomized controlled trial (RCT), 552 eligible college students (Mean = 19.99 ± 1.04 years, 58.3% female) were randomly assigned to one of three groups: PA-first (4 weeks of PA followed by 4 weeks of FVC intervention), FVC-first (4 weeks of FVC followed by 4 weeks of PA intervention), and a control group (8 weeks of placebo treatment unrelated to PA and FVC). A total of 4 web-based assessments were conducted, including at baseline (T1, n = 565), after 4 weeks (T2, after the first behavior intervention, n = 486), after 8 weeks (T3, after the second behavior intervention, n = 420), and after 12 weeks (T4, 1-month post-intervention follow-up, n = 348). In addition, after the completion of the entire 8-week intervention, 18 participants (Mean = 19.56 ± 1.04 years, 55.6% female) who completed the whole program were immediately invited to attend one-to-one and face-to-face semi-structured interviews. The participants were asked about their experience of participating in this program regarding their changes in health behaviors and health-related outcomes. The entire study was conducted throughout the fall semester of 2017. RESULTS Both quantitative and qualitative data supported superior effects on PA, FVC and BMI in two sequential intervention groups compared to the control group. In addition, the quantitative data found no significant behavior change differences between two sequential intervention groups after 8 weeks. But FVC-first group contributed to more maintenance of FVC compared to the PA-first group after 12 weeks. Findings from the qualitative study revealed that both intervention groups reported superior effects for the first addressed behavior after 8 weeks. CONCLUSIONS This study provides comprehensive evidence for the effectiveness of sequentially delivered web-based MHBC interventions on PA and FVC among Chinese college students. The efficacy of two sequential timing interventions on behavior change is mixed in quantitative and qualitative data. The delivery mode of MHBC interventions in the future is discussed. CLINICALTRIAL ClinicalTrials.gov NCT03627949(posted on April 18, 2019). INTERNATIONAL REGISTERED REPORT RR2-10.1186/s12889-019-7438-1