This is an open-access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work, first published in the Journal of Medical Internet Research, is properly cited. The complete bibliographic information, a link to the original publication on https://www.jmir.org/, as well as this copyright and license information must be included.
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.
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.
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.
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.
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.
ClinicalTrials.gov NCT03627949; https://clinicaltrials.gov/ct2/show/NCT03627949
RR2-10.1186/s12889-019-7438-1
Considerable evidence indicates a high prevalence of physical inactivity and insufficient consumption of fruit and vegetables among college students [
College students, who are in a crucial transition stage from late adolescence to adulthood, adopting such unhealthy behaviors can increase the risk of many chronic diseases (eg, cardiovascular diseases, obesity, or type 2 diabetes) and jeopardize their mental health (eg, increase the risk of depression) [
With the burgeoning use of the internet, web-based MHBC intervention programs have been widely applied in various populations [
One debatable question in MHBC research is how to deliver MHBC interventions (ie, delivery timing) to achieve more robust treatment effects and whether the order of the sequential intervention contents makes a difference [
However, previous MHBC studies focused mostly on the combination of heterogeneous categories of behaviors (eg, risk behaviors plus health protecting behaviors). When targeting PA and FVC, which are both health-protecting behaviors, some evidence has indicated that there is a gateway or carry-over effect between PA and FVC [
The health action process approach (HAPA) model was used as the theoretical framework of intervention in this study [
The mixed methods approach can combine the merits of both quantitative and qualitative methods (ie, integrating the power of stories and the power of numbers) and compensate for their respective limitations [
Considering the feasibility and limited resources, an RCT was adopted instead of a cluster RCT with a standard 3-arm, parallel, double-blinded design. The study participants were undergraduate students from a university in the central region of China. The sample size was calculated using G*Power software (Version 3.1). As this study aimed to improve MHBC, PA and FVC were treated as
A total of 634 college students were contacted in their first general physical education (PE) classes with the assistance of PE lecturers during the fall semester of 2017. In China, college students are required to take PE courses based on the national education guideline [
After qualification screening, all 565 eligible students were randomly allocated to 1 of 3 groups. The random number list was generated at the backend management system of the website platform. The three groups consisted of intervention group 1 (PA-first group: first 4-week intervention addressing physical activity, followed by a 4-week intervention addressing FVC; 189/565, 33.5%), intervention group 2 (FVC-first group: first 4-week intervention addressing FVC, followed by a 4-week intervention addressing physical activity; 198/565, 35.0%), and a placebo control group (8-week placebo treatments, which were not relevant to changing actual PA and FVC behavior; 178/565, 31.5%). One week after randomization, participants were invited to attend the session once a week for approximately 25 minutes each time for 8 weeks. All participants were asked to complete the weekly health sessions independently and not to discuss the content of the health sessions with their classmates, roommates, and friends.
In addition to attending the intervention session, all participants were asked to complete electronic questionnaires at 4 time points: baseline (T1, at the beginning of the intervention), after 4 weeks (T2, after the completion of the 4-week intervention on the first behavior), after 8 weeks (T3, after the completion of the 4-week intervention on the second behavior), and after 12 weeks (T4, 1-month follow-up after intervention completion;
We obtained ethical approval from the research ethics committee of Hong Kong Baptist University (FRG2/15-16/032) and registered the study on ClinicalTrials.gov (NCT03627949).
CONSORT (Consolidated Standards of Reporting Trials) flow diagram. FVC: fruit-vegetable consumption; PA: physical activity; PE: physical education.
The intervention was designed based on the health action process approach (HAPA) model, which lasted for 8 weeks [
In addition, given the high dropout rate (31.6% for posttest and 71.2% for the follow-up test) in our previous study [
PA was measured using the Chinese short version of the International Physical Activity Questionnaire (IPAQ-C) [
FVC was measured by using a 4-item scale, asking the participants to count the portions of fruit and vegetables they consumed on average during a typical day [
BMI was measured by asking participants to self-report their body weight (kg) and height (m). BMI was calculated using the formula
Depression was measured using the Chinese version of the Centre for Epidemiologic Studies Depression–10 Scale [
Perceived quality of life was assessed using the short version of the World Health Organization Quality of Life-BREF [
Gender, age, relationship status (single or in a relationship), grade (freshman or sophomore or junior or senior), major, and self-reported health status (bad or medium or good) were included in demographic information.
All measurement instruments were translated into a Chinese version and validated in previous studies with Chinese college students [
The data were analyzed using SPSS (version 25.0; IBM Corporation). Analyses of variances, independent
On the basis of the guideline of descriptive phenomenology, a series of one-on-one and face-to-face semistructured interviews were conducted, which involved three types of questions (open-ended, closed-ended, and conformational) [
To reach theoretical saturation, based on the
The research team jointly developed an interview guide (4 experts in the health psychology domain), including questions, prompts, and guides, based on suggestions from Bryman and Flick [
One-on-one and face-to-face semistructured interviews were conducted after the completion of the 8-week web-based MHBC interventions. On the basis of the interview guide, the main question was used to invite the participants to talk freely, such as “What is your experience with the 8-week web-based health program?” Additional questions were asked during the conversation for clarification and elaboration, such as “If so, can you explain in more detail? What caused this change in your behavior?” Each interview was audio-recorded and lasted approximately 30 minutes. Each interviewee could obtain US $6.5 as a participation remuneration if they completed the interview.
The audio-recorded interview data were transcribed orthographically and organized using NVivo (version 11; QSR International). Thematic analysis was used for data analysis, including six phases: familiarization with the data, generation of the initial codes, searching for themes, reviewing the potential themes, defining and naming themes, and producing the report [
A randomization check indicated that there were no significant differences in baseline characteristics across the 3 groups in relation to gender, age, study year, relationship status, and self-reported health status (
A description of the study sample is provided in
Sociodemographic information, PAa, FVCb, and health outcomes of the study sample at baseline.
Variable | Total (N=552) | PA-first (n=187) | FVC-first (n=195) | Control (n=170) | ||
|
||||||
|
Age (range 18-24 years), mean (SD) | 19.99 (1.04) | 20.07 (1.07) | 19.96 (0.99) | 19.93 (1.06) | |
|
|
|||||
|
|
Male | 230 (41.7) | 79 (42.2) | 78 (40) | 73 (42.9) |
|
|
Female | 322 (58.3) | 108 (57.8) | 117 (60) | 97 (57.1) |
|
|
|||||
|
|
Freshman | 264 (47.8) | 86 (46.0) | 90 (46.2) | 88 (51.8) |
|
|
Sophomore | 229 (41.5) | 77 (41.2) | 84 (43.1) | 68 (40) |
|
|
Junior | 46 (8.3) | 18 (9.6) | 16 (8.2) | 12 (7.1) |
|
|
Senior | 13 (2.4) | 6 (3.2) | 5 (2.6) | 2 (1.2) |
|
|
|||||
|
|
Single | 506 (91.7) | 170 (90.9) | 183 (93.8) | 153 (90) |
|
|
In a relationship | 46 (8.3) | 17 (9.1) | 12 (6.2) | 17 (10) |
|
|
|||||
|
|
Poor | 17 (3) | 5 (2.7) | 9 (4.6) | 3 (1.8) |
|
|
Medium | 358 (64.9) | 122 (65.2) | 125 (64.1) | 111 (65.3) |
|
|
Good | 177 (32.1) | 60 (32.1) | 61 (31.3) | 56 (32.9) |
|
||||||
|
PA (METc-min/week) | 2124.23 (1244.42) | 2180.22 (1314.89) | 2074.45 (1191.03) | 2119.73 (1229.34) | |
|
FVC (Portion/day) | 3.81 (1.75) | 3.84 (1.70) | 3.82 (1.87) | 3.76 (1.68) | |
|
||||||
|
BMI (range 15.62-32.88 kg/m2), mean (SD) | 20.41 (2.45) | 20.32 (2.34) | 20.52 (2.62) | 20.40 (2.39) | |
|
Depression, mean (SD) | 0.92 (0.69) | 0.85 (0.63) | 0.93 (0.73) | 0.98 (0.72) | |
|
Quality of life, mean (SD) | 3.15 (0.67) | 3.23 (0.63) | 3.14 (0.67) | 3.08 (0.71) |
aPA: physical activity.
bFVC: fruit-vegetable consumption.
cMET: metabolic equivalent.
To identify which intervention delivery schedule would be more effective in promoting health behavior change after 8 and 12 weeks, we compared the differences in each health behavior between the PA-first and FVC-first groups at T3 and T4. The results indicated that the 2 intervention groups did not differ significantly from each other in PA at either time point, but there was a significant difference in FVC between the 2 intervention groups (
Results of the generalized linear mixed models with physical activity and fruit–vegetable consumption after 4, 8, and 12 weeks as outcome measures (n=552).
Time and group | PAa | FVCb | ||||||
|
Values | Effect size, Cohen |
Values | Effect size, Cohen |
||||
|
||||||||
|
Time×group | 2.66 | .015 | N/Ac | 12.17 | <.001 | N/A | |
|
Time | 5.24 | .001 | N/A | 36.40 | <.001 | N/A | |
|
Group | 2.05 | .13 | N/A | 13.64 | <.001 | N/A | |
|
||||||||
|
PA-first vs control | 231.58 | .041 | 0.22 | 0.19 | .47 | 0.08 | |
|
FVC-first vs control | 109.70 | .33 | 0.10 | 1.42 | <.001 | 0.58 | |
|
PA-first vs FVC-first | 121.87 | .26 | 0.11 | −1.23 | <.001 | 0.51 | |
|
||||||||
|
PA-first vs control | 282.36 | .018 | 0.25 | 1.13 | <.001 | 0.44 | |
|
FVC-first vs control | 321.19 | .007 | 0.29 | 1.35 | <.001 | 0.52 | |
|
PA-first vs FVC-first | −38.83 | .74 | 0.03 | −0.22 | .41 | 0.08 | |
|
||||||||
|
PA-first vs control | 253.21 | .026 | 0.24 | 0.81 | .02 | 0.34 | |
|
FVC-first vs control | 252.39 | .025 | 0.24 | 1.41 | <.001 | 0.59 | |
|
PA-first vs FVC-first | 0.83 | .99 | <0.01 | −0.60 | .014 | 0.25 |
aPA: physical activity (metabolic equivalent of task-min/week).
bFVC: fruit-vegetable consumption (portion/day).
cN/A: not applicable.
dPost hoc test: least significant difference; mean difference was significant at the .05 level.
Mean values for 3 groups from timepoints T1 to T4. (A) weekly amount of physical activity (metabolic equivalent of task-min/week). (B) daily portion of fruit and vegetable consumption (portion/day). FVC: fruit-vegetable consumption; PA: physical activity.
The descriptive results revealed that the intervention groups had a favorable time effect on health-related outcomes compared with the control condition (all
Mean values for 3 groups from timepoints T1 to T4. (A) BMI (kg/m2). (B) Depression. (C) Quality of life. FVC: fruit-vegetable consumption; PA: physical activity.
Results of the generalized linear mixed models with health-related outcomes (ie, BMI, depression, and perceived quality of life) after 4, 8, and 12 weeks as outcome measures (n=552).
Time and group | BMI | Depression | Quality of life | |||||||||||||||||
|
Value | Effect size, Cohen |
Value | Effect size, Cohen |
Value | Effect size, Cohen |
||||||||||||||
|
||||||||||||||||||||
|
Time×group | 2.34 | .03 | N/Aa | .76 | .60 | N/A | 1.95 | .07 | N/A | ||||||||||
|
Time | 18.29 | <.001 | N/A | 8.21 | <.001 | N/A | 6.69 | <.001 | N/A | ||||||||||
|
Group | .15 | .86 | N/A | 3.61 | .03 | N/A | 6.69 | .001 | N/A | ||||||||||
|
||||||||||||||||||||
|
PAc-first vs control | −0.08 | .76 | 0.03 | −0.17 | .01 | 0.27 | 0.16 | .01 | 0.27 | ||||||||||
|
FVCd-first vs control | 0.09 | .71 | 0.04 | −0.07 | .28 | 0.11 | 0.12 | .07 | 0.18 | ||||||||||
|
PA-first vs FVC-first | −0.17 | .49 | 0.07 | −0.10 | .14 | 0.17 | 0.05 | .46 | 0.07 | ||||||||||
|
||||||||||||||||||||
|
PA-first vs control | −0.11 | .64 | 0.05 | −0.16 | .02 | 0.25 | 0.27 | <.001 | 0.42 | ||||||||||
|
FVC-first vs control | −0.02 | .92 | 0.01 | −0.10 | .13 | 0.15 | 0.18 | .009 | 0.26 | ||||||||||
|
PA-first vs FVC-first | −0.09 | .70 | 0.04 | −0.06 | .37 | 0.10 | 0.09 | .18 | 0.15 | ||||||||||
|
||||||||||||||||||||
|
PA-first vs control | −0.14 | .56 | 0.06 | −0.19 | .003 | 0.31 | 0.30 | <.001 | 0.47 | ||||||||||
|
FVC-first vs control | −0.10 | .66 | 0.04 | −0.15 | .02 | 0.23 | 0.18 | .01 | 0.26 | ||||||||||
|
PA-first vs FVC-first | −0.04 | .88 | 0.01 | −0.05 | .45 | 0.07 | 0.12 | .07 | 0.19 |
aN/A: not applicable.
bPost hoc test: least significant difference; mean difference is significant at the .05 level.
cPA: physical activity (metabolic equivalent of task-min/week).
dFVC: fruit-vegetable consumption (portion/day).
The dropout rate of participants was 14.3% (79/552) from T1 to T2, 14% (66/473) from T2 to T3, and 15.7% (64/407) from T3 to T4. The aggregated dropout percentage was 26.3% (145/552) from T1 to T3, and 37.9% (209/552) from T1 to T4. There were no between-group differences in the percentage of participants with incomplete data at T2, T3, and T4 (
Overall, sensitivity analyses exhibited similar results for all dependent variables, except for the perceived quality of life, and the time and treatment effect was found to be statistically significant (
A total of 18 participants attended the interview study, including 10 females and 8 males, ranging in age from 18 to 22 years (mean 19.56, SD 1.04 years); 89% (16/18) of the participants were single; 61% (11/18) of the participants reported a medium level of health status, while 39% (7/18) indicated a good level of health status.
Demographic information of interviewees (n=18).
Participant ID | Group | Gender | Age (years) | Marital status | Health status |
1 | IG1a | Female | 19 | Single | Medium |
2 | IG1 | Male | 20 | Single | Medium |
3 | IG1 | Male | 19 | Single | Medium |
4 | IG1 | Male | 19 | Single | Medium |
5 | IG1 | Female | 20 | Single | Good |
6 | IG1 | Female | 19 | Single | Medium |
7 | IG2b | Male | 18 | Single | Good |
8 | IG2 | Male | 19 | Single | Medium |
9 | IG2 | Male | 18 | Single | Good |
10 | IG2 | Female | 20 | Single | Medium |
11 | IG2 | Female | 19 | Single | Medium |
12 | IG2 | Female | 21 | In a relationship | Medium |
13 | CGc | Female | 21 | Single | Good |
14 | CG | Female | 20 | Single | Good |
15 | CG | Female | 19 | Single | Medium |
16 | CG | Male | 20 | Single | Good |
17 | CG | Female | 22 | Single | Good |
18 | CG | Male | 19 | In a relationship | Medium |
aIG1: physical activity–first group.
bIG2: food-vegetable consumption–first group.
cCG: control group.
All participants were invited to talk about their experiences and participation in the web-based MHBC intervention program. Through thematic analysis, four major themes were identified: (1) PA and FVC behavior, (2) health-related outcomes, (3) correlates of health behavior change, and (4) contamination detection.
This theme focused on how the students self-assessed their current status and changes in PA and FVC behavior over the previous 8 weeks. It contained three subthemes: (1) improving health behaviors, (2) no change in health behaviors, and (3) decrease in health behaviors.
In total, 4 of the 12 (33%) students in the intervention groups reported improvement in their PA in the last 8 weeks (participants 1, 2, 4, and 6), while no student in the control group indicated an increase in this behavior. In addition, 2 students with improved PA stated that they understood the importance of performing sufficient PA through the web-based health program (participants 2 and 6). They noted some improvements, even after encountering obstacles at the start of implementation. For example:
I think the health program is quite helpful...I had not paid much attention to the health issue, especially since the last year of high school, you know, I was busy with my studies...But recently, thanks to the health learning sessions, I started to worry about my health status and I really improved this behavior these days, I feel that doing some physical activity makes all of my days...
For FVC, the feedback was more positive in the intervention groups, as 10 of the 12 (83%) students (except participants 1-4) described their improvement in the consumption of fruit and vegetables per day after receiving the health interventions. In comparison, only one student (participant 18) in the control group reported an increase in this behavior:
I eat more fruit and vegetables every day after participating in the health learning program...I pay more attention to this health issue now.
The results revealed that 5 of the 12 (41%) students (participants 3, 5, 7, 8, and 10) in the intervention groups reported maintaining their physical activity, while 2 of the 6 (33%) students in the control group reported no change in their weekly amount of PA (participants 17 and 18). The participants explained the following:
In the last two months, there has been no prominent change in this behavior...I maintain the same intensity and the same amount of weekly physical activity.
For FVC, two students (participants 1 and 4) in the intervention groups reported no change in their daily consumption of fruit and vegetables compared with four students in the control condition group (participants 13, 14, 16, and 17).
Of the 12 students, 3 (25%) students in the intervention groups reported reducing the weekly amount of PA for diverse reasons, such as weather and study-related activities (participants 9, 11, and 12). Of the 6, 4 (66%) students in the control group also witnessed a decrease in PA in the last 8 weeks (participants 13-16). For FVC, only one student in the control group reported reducing her daily consumption of fruit and vegetables (participant 15): “I used to eat apples or grapes every day, but now I do not because of the freezing weather and other reasons.”
This theme focused on how students self-assessed their physical and mental health outcomes. It contained three subthemes:
Of the 12 students, 4 (33%) in the intervention groups showed an increase in body weight (participants 2, 4, 9, and 11), and 3 of the 6 students (50%) in the control group described a similar trend (participants 13, 15, and 16). Two students in the intervention groups explained that their body weight increased because they were fitter and had more muscles these days (participants 2 and 4), but no further elaboration and explanation was obtained from the students in the control group. For example:
My body weight has increased a bit, but I think it is due to my muscles...there is no obvious change in my body fat.
Most of the students experienced no symptoms of depression in the previous 8 weeks (12/18, 66%). Although no student described the change in their level of depression, most students recognized the positive effects of PA and FVC in reducing depression. In particular, six students mentioned that PA can help fight depression (participants 2, 3, 5, 10, 17, and 18). Two students (participants 2 and 12) described the positive effect of FVC on reducing depression and felt that this influence was weaker than that of physical activity. For instance:
Doing exercise is useful for coping with depression and eating fruit and vegetables can put me in a good mood...But, I think that dietary behavior is not as effective as exercise in dealing with this problem...
In total, 10 of the 18 (55%) students felt that their quality of life was good before participating in the health program. A total of 10 respondents (4 in the intervention groups and 6 in the control group) indicated no change in their quality of life. Two respondents indicated a decrease in this aspect (participants 9 and 11), and 6 respondents in the intervention groups (participants 2, 3, 5, 6, 8, and 12) felt that they were more energetic and their perceived well-being improved after participating in the web-based health program. In total, 9 of the 18 (50%) students recognized that consuming enough fruit and vegetables could help, while 6 students indicated the positive influence of regular PA on improving their perceived quality of life (
After participating in the health learning program, I exercised more, it brought me a good spiritual outlook...I felt that I slept better...Greasy food made me uncomfortable and fresh fruit and vegetables improved my well-being.
This theme reflected the students’ narratives of the correlates of health behavior change. It contained two subthemes: university policy for PA and barriers to PA and FVC.
The respondents mentioned that to encourage students to engage in PA, their university had a policy in place, named
The Ham Run task was okay for me, I completed it at the end of October...I feel that I was less active after completing this task.
The weather is freezing and the playground is quite far from my dormitory, so I rarely go outside to exercise...
Sometimes I want to exercise indoors, but the venues are always unavailable...it is really difficult.
For FVC, the barriers included the weather, the supply of university canteens, and financial issues. For instance, some students explained the following:
I do not want to eat vegetables because the weather is freezing and my teeth need hot food.
I cannot choose what I want to eat...it is decided by the university canteens...I hope they can improve their supply of vegetables.
The fruit sold nearby is quite expensive...I can only afford one serving of fruit per day...I do not want to ask my family for more money.
This theme consisted of three subthemes related to potential intervention contamination:
All students in the intervention and control groups indicated that they did not discuss the content of the health program with other classmates in the same PE class. The students provided additional information, emphasizing that there was a low possibility for students from the same department to enroll in the same PE class to discuss the content due to the university’s curriculum selection system. Some students explained the following:
I did not discuss the content with others, as I am not familiar with my classmates and we come from different departments...it is impossible for us (students in my department or roommates) to select the same PE class...
All students explained that they did not discuss the content with other students participating in the health program but were enrolled in a different PE class. For instance:
I do not know if the students enrolled in other PE classes were also invited to join the health program...I will not communicate with others, even if I find some acquaintances participating in this program.
In total, 17 of the 18 students (94%) reported that they did not discuss the health program with their friends, roommates, and family. Only 1 student told her parents about her participation in the health program, but did not discuss the content of the intervention:
I told my mother that I participated in a health learning program and she encouraged me to adhere to it...but I did not give details.
For the quantitative part of the study, most of the research hypotheses were supported. For the qualitative analysis, 4 main themes with a couple of subthemes were identified through thematic analysis. The qualitative findings corresponded to the quantitative findings, providing an in-depth understanding of changes in PA and FVC behavior in Chinese college students.
The principal expected intervention effects on the behavioral indicators of PA and FVC were identified in the quantitative study. From the findings of the RCT, compared with students in the placebo control condition, students in both intervention groups reported significant and favorable changes in the weekly amount of PA and daily consumption of fruit and vegetables, which supported hypothesis 1. The findings were more positive than those of our previous study, in which a significant treatment effect was only supported for FVC change in Chinese college students [
In terms of the differences in intervention effects on behavioral changes between the 2 delivery timings (PA-first vs FVC-first), hypothesis 3 was partially supported in the RCT. We found that there was no significant difference in PA between the 2 intervention groups at either time point, whereas the FVC-first group had significantly higher consumption of daily fruit and vegetables after 12 weeks than the PA-first group. Our finding is partially consistent with a previous study in middle-aged adults, which found that the PA-first group showed higher PA than the diet-first group (Cohen
The findings of the RCT revealed that both intervention groups showed more changes in BMI compared with the control group, which partially supported hypothesis 2. As most of the participants were freshmen and sophomores and the data collection (ie, T3 and T4) was conducted near the beginning of the winter holidays, most of the participants increased their body weight because of the seasonal time that the study was conducted (special transition stage of life and seasonal variation) [
For depression, in the RCT, we did not find a significant effect, probably because of the floor effect [
It is not surprising that the dropout rates in this study were significantly lower than those in our previous study at both the postintervention test (26.3% vs 31.6%) and at the 1-month follow-up (37.9% vs 71.2%) [
The 4 themes provided a clear picture of the participants’ experiences and perceptions of participating in the web-based MHBC intervention program. The first theme reflected the perceived changes in PA and FVC of participants. Most of the students in the intervention groups indicated a favorable change in these 2 behaviors, especially for FVC (10/12, 83% indicated an increase). In contrast, most students in the control group showed a decrease in PA (4/6, 66%) and no improvement or decline in FVC (5/6, 83%). Theme 2 reflects participants’ perceptions of their change in health-related outcomes. Around half of the students mentioned an upward trend in body weight (7/18, 38%), most of whom indicated a decrease in PA (5/7, 71%). A total of 2 students who improved PA also showed a slight increase in their body weight and attributed it to muscle enhancement. No statistically significant effects on depression and quality of life were identified from the quantitative data, and we found that most students reflected a good knowledge of the benefits of adequate PA and FVC in depression (5/12, 41%) and quality of life (10/12, 83%) after receiving the web-based MHBC interventions. Despite no explicitly positive comments about the change in these 2 indicators, half of the students in the intervention groups described that they became more invigorated and had a better perceived quality of life after participating in the web-based health interventions.
From the qualitative study, we also found some additional information that underlined the crucial role of university policy in promoting physical activity and revealed prominent barriers to PA and FVC behavior. The students described the university’s relevant policy, which motivated their engagement in physical activity. To some extent, this can explain the situation in the previous RCT of participants reporting a relatively high amount of weekly physical activity. These results also echoed the suggestions from other studies, emphasizing the importance of including
Finally, theme 4 reflected the results of contamination detection, which provided qualitative evidence and explanation for a low risk of contamination in this study.
This study has considerable theoretical and practical implications for further web-based MHBC interventions. The use of the mixed methods approach increased the external validity of the quantitative data for factor-outcome relationship and thus was generalizable to a larger college student population and also ensured the strong internal validity of the in-depth descriptive qualitative data regarding complex context-specific issues and phenomena (eg, participating in a web-based MHBC intervention program) [
Using a mixed methods approach, the study demonstrated the potential of a web-based and theory-based MHBC intervention for promoting both PA and FVC among Chinese college students. Moreover, the differences in intervention effects on changes in PA and FVC between the 2 delivery sequences were primarily identified in the quantitative study. In addition, the qualitative interviews provided an in-depth understanding of the quantitative findings and identified PA policy and external barriers as other determinants of change in PA and FVC. The overall findings provide new insights into MHBC research, providing theoretical and practical implications for future design and the application of web-based MHBC interventions.
Study process.
Intervention variables and content for the 2 intervention groups and the setting for a placebo control group.
Behavioral change techniques.
Interview guide.
Trustworthiness of the qualitative study.
Consolidated Criteria for Reporting Qualitative Studies (COREQ) checklist (32-item).
Sensitivity test using a per-protocol strategy.
A summary of the qualitative findings.
CONSORT-eHEALTH checklist (V 1.6.1).
fruit-vegetable consumption
health action process approach
multiple health behavior change
physical activity
physical education
randomized controlled trial
visual analogue scale
This research was supported by the Faculty Research Grant of the Hong Kong Baptist University (FRG2/15-16/032). The funding organization had no role in the study design, study implementation, manuscript preparation, or publication decision. This work is the responsibility of the authors [
YD, WL, and SL conceived and designed the study. YD, WL, and YW contributed to the preparation of the study materials. YD, WL, and YW collected the data. WL, YW, and YD screened and analyzed the data. WL and YD drafted and revised the manuscript. All authors have reviewed and approved the final version of the manuscript.
None declared.