The PRISMA flowchart in Figure 1 outlines the search and screening process. The systematic search resulted in 18,959 potentially relevant articles. In addition, we found one article through hand searching. After removing duplicates, 11,282 articles were screened by title and abstract, and 61 full-text articles were assessed for eligibility. The main reasons for exclusion of full-text articles were ineligible study population, i.e., the participants were younger than 15 or older than 20 years, or inappropriate setting, i.e., middle school, university, etc. In total, nine articles met the aforementioned inclusion criteria and were included in the qualitative synthesis [36–44]. Agreement among reviewers was moderate after title and abstract screening (k = 0.53), and very good after full-text screening (k = 0.87) [45].
Study Quality
Quality ratings are shown in Table 2. With six out of nine studies, the global rating of the majority of studies was weak [36–38, 41–43]. Only one study was rated as strong [40], and two studies were rated as moderate [39, 44]. For the individual EPHPP domains across all studies, blinding was the most weakly rated domain (n = 7) [36–38, 41–44]. However, study design and selection bias had no (n = 0) and very few (n = 2) weak ratings, respectively [36, 37]. Four studies were rated as having strong study design, including randomized controlled trial [44] or cluster randomized controlled trial study designs [39, 40, 42]. The other five studies were rated as moderate with respect to study design strength, with quasi-experimental designs (two groups pre and post [36, 37, 43] or one group pre and post [38, 41]). The other domains differed more in their ratings. While confounders were rated as either strong or weak, data collection method, as well as withdrawals and dropouts, varied similarly in their ratings between weak, moderate, and strong.
Table 2: Assessment of study quality using the quality assessment tool for quantitative studies
Author, year
|
Selection bias
|
Study design
|
Confounders
|
Blinding
|
Data collection methods
|
Withdrawals and dropouts
|
Global rating
|
Angerer et al., 2015
|
weak
|
moderate
|
weak
|
weak
|
weak
|
moderate
|
weak
|
Braun et al., 2014
|
weak
|
moderate
|
weak
|
weak
|
weak
|
moderate
|
weak
|
Chen et al., 2001
|
strong
|
moderate
|
weak
|
weak
|
moderate
|
strong
|
weak
|
Hankonen et al., 2017
|
moderate
|
strong
|
strong
|
moderate
|
moderate
|
weak
|
moderate
|
Lee et al., 2011
|
moderate
|
strong
|
strong
|
moderate
|
strong
|
strong
|
strong
|
Sickinger et al., 2018
|
moderate
|
moderate
|
weak
|
weak
|
weak
|
weak
|
weak
|
Spook et al., 2016
|
moderate
|
strong
|
strong
|
weak
|
moderate
|
weak
|
weak
|
Verloigne et al., 2017
|
moderate
|
moderate
|
weak
|
weak
|
strong
|
weak
|
weak
|
Walter et al., 2013
|
moderate
|
strong
|
strong
|
weak
|
strong
|
strong
|
moderate
|
Study characteristics
Table 3 provides an overview of study characteristics in detail. Seven of the nine studies were conducted in Europe: four in Germany and one each in Belgium, Finland, and the Netherlands. Two studies were performed at community colleges in Taiwan. Three German studies took place in workplace settings, while the other European studies were conducted at VET schools. Sample sizes ranged from 23 to 231 participants, with a mean age between 15.5 and 19.4 years.
Table 3: Study characteristics
Author, year
|
Country
|
Study design
|
Target group1; setting
|
Sample size (n)
|
Sex
|
Mean age
|
Angerer et al., 2015
|
Germany
|
controlled study
|
overweight apprentices; automobile factory
|
IG: 60 CG: 32
|
no data
|
15-19 (range)
|
Braun et al., 2014
|
Germany
|
controlled study
|
young adults with learning impairments; rehabilitation-institution for vocational training
|
IG: 27 CG: 25
|
46.2% female
|
18.9
|
Chen et al., 2001
|
Taiwan
|
pre-post design
|
overweight adolescent nursing students; junior college
|
IG: 55
|
only female
|
15.5
|
Hankonen et al., 2017
|
Finland
|
CRT2
|
vocational students; vocational school unit
|
IG: 26 CG: 17
|
85% female
|
18.9
|
Lee et al., 2011
|
Taiwan
|
CRT2
|
nursing students; junior college of nursing
|
IG: 46 CG: 48
|
only female
|
16.2
|
Sickinger et al., 2018
|
Germany
|
pre-post design
|
trainees in the metal industry; major company in the metal industry
|
IG: 514
|
only male
|
17.0
|
Spook et al., 2016
|
The Netherlands
|
CRT3
|
secondary vocational education students; vocational education schools
|
IG: 105 CG: 126
|
62.8% female
|
17.2
|
Verloigne et al., 2017
|
Belgium
|
controlled study
|
lower-educated girls; vocational and technical schools
|
IG: 915 CG: 1055
|
only female
|
16.0
|
Walter et al., 2013
|
Germany
|
RCT
|
apprentices; Institute of Technology
|
IG: 12 CG: 11
|
52% female
|
19.4
|
CG = control group; CRT = cluster randomized controlled trial; IG = intervention group; RCT = randomized controlled trial; 1The target group is defined as young adults attending VET. The use of different terminology for VET students (e.g., apprentices or trainees) depends on the respective study. 2Four classes of one school/college were randomized. 3Four schools were randomized. 4N = 74 in total, but only men were included in the analysis. 5Allocated to three control and intervention schools each.
|
Intervention characteristics
Intervention details are presented in Table 4, with interventions ranging from four weeks to two years in duration. Regarding the addressed behavior, the interventions either focused on PA only [37, 39, 40, 43, 44] or followed a multi-behavioral approach in which, for example, alcohol consumption, life-skills training, and/or nutrition were treated in addition to PA [36, 38, 41, 42]. Three interventions comprised multiple components that either addressed a person’s behavior or additionally adjusted the conditions in the setting [36, 39, 43]. For example, Verloigne et al. [43] offered various PA measures, while Angerer et al. [36] and Hankonen et al. [39] modified the context by providing PA equipment. The other six one-component interventions focused solely on individuals’ behavior, comprising stand-alone information and course offerings that included the provision of information or behavioral training (e.g., information, motivation, and counselling).
Furthermore, the interventions differed in the way they were developed and implemented. Essentially, the interventions could be classified into top-down and bottom-up interventions. Top-down interventions were developed and implemented by experts and followed a theoretical and scientific orientation in terms of their goals and content [36–38, 40, 42, 44]. By contrast, the bottom-up interventions followed a participatory approach, ranging from the target group’s involvement in designing teaching units [41], through a stepwise intervention development involving different stakeholders [39], to the entire intervention development and implementation using a co-creation approach [43].
Further special characteristics of individual studies included, for example, an online-based intervention in the form of a multimedia game [42] or an additional intervention for teachers to reduce their students’ sedentary behavior in class [39].
Study findings
The studies’ outcomes are grouped into four major categories: PA, physical fitness, physiological parameters, and psychological factors. Most studies measured more than one of these outcome categories.
Seven studies measured PA either subjectively using standardized questionnaires or objectively using accelerometers. Four of the seven studies [38, 40, 43, 44] found significant baseline to post-intervention improvements in PA. Among these, two studies subjectively measured PA and identified a significant intervention effect on activity level [38] and extracurricular sports participation [43], while two studies objectively measured PA and found significant effects. Thus, Lee et al. [40] revealed a significant increase in the number of aerobic steps, and Walter et al. [44] indicated a significant increase in mean activity intensity. Three studies did not find significant changes in PA level [39, 41, 42].
Physical fitness components were tested by motor performance tests or body analyses in six studies. Two of these studies identified a significant intervention effect on endurance [37, 44]. In another study, a significant decrease in body weight and weight-for-length index was found following the intervention [38]. The remaining three studies found no significant changes in body mass index, body composition, or cardiopulmonary endurance [36, 39, 40].
Physiological parameters measured through blood pressure or blood tests were examined in three studies. Only Chen et al. [38] reported significant improvements from baseline to post-intervention on physiological parameters, in this case systolic blood pressure, high-density lipoprotein, and total serum cholesterol. In two other studies, no significant effects on blood pressure, heart rate, sugar metabolism, or fat metabolism were found [36, 37].
Eight studies assessed psychological factors using standardized questionnaires. Of these, three identified a significant change in psychological factors. Hankonen et al. [39] reported a significant improvement in the use of behavior change techniques from baseline to post-intervention in the intervention group. Furthermore, Sickinger et al. [41] found significant improvements in general self-effectiveness expectations, and Verloigne et al. [43] reported a significant intervention effect on self-efficacy. Five studies did not find significant changes in psychological factors, including determinants of PA, mood state, psychological aspects related to mental health, self-efficacy, or self-rating of physical and mental health characteristics [36, 37, 40, 42, 44].
Overall, two studies indicated significant effects in all measured outcome variables [38, 43], whereas two other studies did not find significant effects in any measured outcome variables [36, 42].
Table 4: Intervention characteristics and study findings
Author, year
|
Intervention group
|
Control group
|
Period
|
Outcome measure
|
Effects and effect sizes (d)
|
Angerer et al., 2015
|
"Fit4U": intensive nutrition counselling, sports facilities, life-skills training, and introduction of health lessons into compulsory education in VET school, provision of sports equipment during breaks;
behavior- and environment-oriented measures;
multi-behavior (PA, nutrition, life-skills training)
|
no intervention offered
|
2 years
|
PF: BMI, cardiopulmonary fitness
PP: sugar and fat metabolism
PsF: psychological aspects related to mental health
|
no significant changes
|
Braun et al., 2014
|
one hour of individually adapted circuit training with endurance and strength training components once a week;
single behavior (PA only)
|
compulsory physical education
|
1 year
|
PF: aerobic step test, coordination, flexibility, BMI;
PP: blood pressure, heart rate;
PsF: self-rating of physical and mental health characteristics
|
PF: significant increase in the number of steps (dcorr = 1.17) and duration of the step test (dcorr = 0.74)
|
Chen et al., 2001
|
Health Promotion Counselling: total of 8 hours of whole group education (nutrition behavioral change, exercise behavior modifications, instruction on physiological side effects of being overweight and the benefits of weight reduction, life appreciation, interpersonal support and stress management – 2 hours each), additional 12 hours of small-group health promotion counselling;
multi-behavior (PA, nutrition)
|
no control group
|
1 year
|
PA: exercise behavior
PF: body weight, WLI
PP: blood pressure, HDL, LDL, TG, TC
|
PA: significant increase in PA level (d = 0.74)
PF: significant decrease in body weight (d = 0.21) and WLI (d = 0.28)
PP: significant decrease in systolic pressure (d = 0.87), HDL (d = 0.77) and TC (d = 0.26)
|
Hankonen et al., 2017
|
"Let's Move It": 6 hours of group-based intervention for students, two 2-hour training workshops for teachers to reduce their students' sitting in class, physical choice architecture (providing PA equipment to enable light PA in classrooms);
individual and environmental changes;
participatory approach involving stakeholders in stepwise intervention development;
single behavior (PA only)
|
standard care, i.e., normal curriculum plus a leaflet on recommendations for youth PA
|
5 weeks
|
PA: moderate-to-vigorous PA
PF: body composition
PsF: self-reported use of behavior change technique
|
PsF: significant increase in use of behavior change technique (0.74 < dcorr < 0.90)
|
Lee et al., 2011
|
"SPAA-G": original content and activity in a physical education class, plus school-based PA intervention for adolescent girls program, combining the theoretical foundation of self-efficacy theory and provision of a pedometer;
single behavior (PA only)
|
original content and activity in a physical education class
|
12 weeks
|
PA: aerobic step test
PF: cardiopulmonary endurance
PsF: perceived self-efficacy
|
PA: significant increase in the number of steps (dcorr = 0.78)
|
Sickinger et al., 2018
|
12 theoretical and practical teaching units between 65-90 minutes each on the topics of nutrition, alcohol and nicotine consumption, and PA during VET;
participatory approach involving 6 focus groups in the sensitization unit;
multi-behavior (PA, nutrition, alcohol and nicotine consumption)
|
no control group
|
11 months
|
PA: at least 1 hour of PA per day
PsF: general self-effectiveness expectations
|
PsF: significant increase in general self-effectiveness expectations (d = 0.27)
|
Spook et al., 2016
|
"Balance It": serious self-regulation game designed to target dietary intake and PA; this tailored, interactive multimedia game could be played at any time and place desired on a daily basis, entailing a combination of behavior change techniques derived from self-regulation theory with serious game elements;
multi-behavior (PA, nutrition)
|
waiting list control group: no intervention between measures
|
4 weeks
|
PA: moderate PA, vigorous PA, active transport
PsF: determinants of PA
|
no significant changes
|
Verloigne et al., 2017
|
specific interventions were developed by a co-creation group; several co-creation sessions during lunch break (about 50 minutes); group brainstormed on what it could do to change specific behaviors and ascertain what might be relevant for the girls in their school;
co-creational approach;
single behavior (PA only)
|
control schools did not receive any information on PA or health outside the normal curriculum
|
6 months
|
PA: time spent in PA
PsF: self-efficacy, perceived benefits of PA, perceived barriers to be physically active
|
PA: significant increase in extracurricular sports participation (d = 0.19)
PsF: significant intervention effect on self-efficacy (d = 0.63)
|
Walter et al., 2013
|
aerobic endurance intervention: instructed outdoor running training twice a week; initial duration of 30 minutes was increased continuously to 60 minutes over 10 weeks;
single behavior (PA only)
|
instructed not to alter their PA and exercise patterns during the control period
|
10 weeks
|
PA: mean activity intensity
PF: aerobic endurance capacity
PsF: mood state
|
PA: significant change in mean activity intensity (d = 0.87)
PF: significant change in aerobic endurance capacity (1.03 < d < 1.40)
|
BMI = body mass index; HDL = high-density lipoprotein; LDL = low-density lipoprotein; PA = physical activity; PF = physical fitness; PP = physiological parameters; PsF = psychological factors; TC = total serum cholesterol; TG = triglycerides; VET = vocational education and training; WLI = weight-for-length index
|