What do we know about physical activity interventions in vocational education and training? A systematic review

The world is facing a high prevalence of physical inactivity among young people. Many adolescents do not meet the recommended guidelines of 60 min of moderate to vigorous physical activity per day (PA) [1‐3]. A German study, for example, reports that only 7.5% of girls and 16.0% of boys between the ages of 14 and 17 meet these recommendations [4]. These alarming insights are reinforced by evidence that PA continues to decline between adolescence and young adulthood [5]. On the other hand, PA behavior adopted during childhood and adolescence is likely to continue into adulthood [6]. Incontrovertible evidence indicates lifelong health benefits from a physically active lifestyle [7, 8], underlining the need for actions that promote PA. Furthermore, the period ranging from adolescence to young adulthood is an important one for prevention measures, as many health-related behaviors, such as PA patterns, are learned and consolidated at this stage in life [9, 10]. At the same time, this transitional phase also is marked by some major life challenges. Difficulties in the transition from childhood to adulthood or from school to working life – and, thus, to independence and autonomy – influence health and well-being, putting people at greater risk at this life stage [11].

For a large number of young people who do not pursue higher education after secondary school, vocational education and training (VET) is the first step toward working life. In VET, students acquire the knowledge, skills, and competencies specific to particular occupations to gain optimal professional qualifications [12]. A great deal of heterogeneity exists between national VET systems. In Germany, VET is organized in a dual apprenticeship system combining school-based learning and company-based training. Other countries with well-established apprenticeship systems include Austria, Denmark, and Switzerland. In addition to the dual apprenticeship system, VET globally can be categorized into two other systems: school-based VET following a formal curriculum that combines general and occupation-specific knowledge (e.g., France, Sweden, United States) and informal-based VET outside of formal or general schooling (e.g., India, many African countries) [13, 14]. Accordingly, not only do the various institutions in which VET takes place differ, but so also do the respective curricula and duration of VET programs. Nevertheless, they all are linked by a common goal: preparing young people with skills to enter the labor market [15]. Higher education can also prepare people for the world of work, the difference being that VET is characterized by earlier specialization in a particular occupational field and lower socioeconomic status (SES) [14].

Since low SES in adolescence is a predictor of physical inactivity in adulthood [16] and adolescents attending VET often belong to families with low SES [17], these individuals form a group that is vulnerable to engaging in insufficient PA. As PA has not only health-promoting potential but also positive influence on a person’s work ability [18], PA promotion in VET programs are once again coming to the fore in research and practice [19, 20]. In the light of demographic change and the shortage of skilled workers, it is highly important and societally relevant that the future workforce has a good work ability [21].

While numerous studies have confirmed the effectiveness of PA promotion measures in school, university, and workplace settings [22‐26], research is lacking about their effectiveness in the VET context. Notwithstanding, VET is a promising setting for PA promotion, as VET programs have a wide reach among adolescents and young adults, providing the opportunity to raise awareness of PA and health at an early stage of life [20, 27]. Against this backdrop, this systematic review aims to (1) synthesize and review the available literature on PA-promoting interventions in VET and (2) examine interventions’ effects on PA-related outcomes such as PA level, physical fitness, physiological parameters, or psychological factors.

This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines [28] (see Additional file 1) and was registered prospectively in PROSPERO (CRD42018109845).

The PRISMA flowchart in Fig. 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].

To our knowledge, this is the first systematic review to identify PA-promoting interventions in VET and to examine their effects on PA-related outcomes such as PA level, physical fitness, physiological parameters, or psychological factors. In total, nine studies met the inclusion criteria, covering a broad range of interventions and outcomes measured. All but two studies found significant improvements for at least one PA-related outcome, with the majority of studies indicating a mix of both significant and non-significant effects. These heterogeneous effects, coupled with the overall weak study quality, limited our ability to draw clear conclusions about the potentially most effective intervention strategies.

An existing problem, confirmed in our review, is the lack of studies dealing with the promotion of PA in VET. As already assumed, very few studies have focused on this issue, and unfortunately, those that are available are of poor quality. Ensuring high study quality while simultaneously taking local requirements and conditions into account is particularly difficult in real-world settings [46]. Accordingly, methodologically complex and comprehensive studies are necessary to better examine interventions’ effectiveness in the VET field [38]. Regarding the countries in which the studies were carried out, it is striking that all but two Taiwanese studies were conducted in Europe, whereas Anglo-American studies were completely absent. One reason for this could be the large number of occupations with a required VET qualification and the associated high importance of a formal curriculum-based VET in European countries, such as the Benelux and Scandinavian countries or, in particular, Germany [13]. However, pursuing higher education by enrolling in colleges or universities is the most common pathway after graduating from high school in the U.S. [47]. Thus, the lack of studies is astonishing and also indicates a research gap in physical activity promotion with VET students. In summary, the evidence for PA promotion in the VET context is sparse, comprising data mainly only from European studies. Furthermore, due to VET systems’ heterogeneity in Europe, our findings cannot be generalized.

Nevertheless, we tried to identify further conspicuous aspects and similarities regarding intervention characteristics, such as their approaches, components, and content. One remarkable result that emerged from our review is that both bottom-up and top-down interventions revealed positive effects. Taking a closer look, interventions designed with a participatory bottom-up approach tended to improve relevant psychological factors related to PA, such as self-efficacy or the use of behavior change techniques, but not PA levels per se [39, 41, 43]. In contrast, none of the five top-down interventions that measured psychological factors indicated positive effects for this set of outcomes [36, 37, 40, 42, 44]. Out of a total of six studies using top-down interventions, four reported significant improvements in PA level, physical fitness, and/or physiological parameters [37, 38, 40, 44]. Thus, top-down interventions seem to improve outcomes on the physical level. According to existing literature, “traditional” interventions designed using a top-down approach have shown limited success and have been criticized for their lack of long-term sustainability [48‐50]. A possible reason for these interventions’ failure may be a lack of consideration of the complex influence of different factors between the individual and environment.

To counteract this problem, bottom-up interventions seem to be promising. With a participatory or co-creational approach, it is possible to develop interventions tailored to the needs of the target group and given setting, thereby increasing acceptance by the target group and facilitating the intervention’s sustainability [49, 51, 52]. From our perspective, we cannot estimate the long-term effectiveness and sustainable implementation of these interventions, as no long-term follow-ups or reports on the continuation and anchoring of the interventions exist. Therefore, it is not yet possible to conclude which approach is more appropriate; the tendency for bottom-up approaches to improve outcomes on the psychological level and for top-down approaches to improve outcomes on the physical level needs to be investigated in further studies. In such studies, recommendations for the intervention research process made by van Sluijs et al. [52, 53] also should be taken into account. The authors report an apparent willingness among adolescents to increase PA as evidenced by an expressed desire to do more types of PA more often. In reality, this intention often fails due to difficulty translating intention to action. Therefore, it is necessary to transform this enthusiasm into effective PA-promoting interventions [53]. Active engagement in the form of participatory or co-creational approaches could be a key to success in developing acceptable and attractive interventions [52].

Recent literature recommends multi-component interventions that combine various measures to promote PA, e.g., behavioral, educational, and/or environmental elements [22, 51, 54]. In particular, combining individual and environmental changes is also acknowledged in other studies, as effective behavioral changes in individuals require supportive policies and environments [55, 56]. Although our data are not strictly conclusive, the two studies showing significant effects in PA level and psychological factors [39, 43] seem to support this approach. With several comprehensive measures, it is possible to extend the target group’s reach and create a PA-friendly environment. To achieve this, PA intervention components of the examined studies included offering various PA programs, providing PA equipment, and conducting workshops for teachers as experts for PA promotion. In our case, the two studies in which multi-component interventions yielded significant effects also were interventions developed based on a participatory or co-creational approach. Therefore, the use of a bottom-up approach may be a promising strategy to create diverse and comprehensive PA-promoting measures that consider both the individual and environment.

Prior studies have discussed the benefits and effectiveness of multi-behavior interventions compared with single-behavior interventions. In theory, it is assumed that different unhealthy behaviors co-occur and are mutually dependent. Therefore, targeting more than one behavior, rather than just a single behavior, could lead to greater health benefits through lifestyle changes [57, 58]. However, in practice, such multi-behavioral interventions have proved to be an obstacle to success [22, 59, 60]. Our review demonstrated mixed results in terms of single-behavioral and multi-behavioral interventions’ effectiveness. Two studies reported positive results from their multi-behavioral interventions [38, 41], while the only two studies that showed no significant effects also comprised multi-behavioral interventions [36, 42]. In contrast, all studies that focused only on PA behavior revealed significant effects on at least one outcome. On the basis of our review, multi-behavioral interventions can work, but changing multiple health behaviors simultaneously also can lead to excessive demands and burdens on participants and thus reduce the interventions’ effectiveness [57].

Against this backdrop and the results of our review, the VET field seems to be promising for the implementation of PA-promoting interventions, as many young people can be reached in an environment where a time structure and organizational framework are provided. Our review highlights the positive, yet inconsistent, effects from PA-promoting interventions in VET. Thus, it is difficult for us to declare explicit practical recommendations based only on our results. Moreover, the different VET systems and, consequently, the various contextual factors make it difficult to interpret our results. In future studies, clearer reporting on the intervention and, in particular, on the contextual factors would be helpful to provide substantive implications and recommendations [61]. Nevertheless, regarding the results from van Sluijs et al. [52, 53], multi-component interventions tailored to the target group and context seem to be a good way to increase acceptance and participation and, thus, interventions’ effectiveness. To understand interventions’ effectiveness and make further recommendations regarding the development and implementation of PA interventions in VET, high-quality studies with long-term follow-ups conducted in real-world settings are needed.

The present systematic review provides detailed insight into literature concerning the effectiveness of interventions that promote PA in VET. First, with most of the examined studies revealing significant improvements in at least one PA-related outcome, PA interventions have the potential to be efficacious in VET. However, the results are inconclusive, as most studies indicated a mix of both significant and non-significant effects. Second, in contrast to the numerous studies on PA interventions in young people, only a few published studies feature PA interventions that are targeted specifically at VET students. Third, it has become clear that the available studies are mainly from the European and Asian regions. A global perspective on the topic is therefore not yet possible at present. Thus, these results also underline the need for further research in this new research area. In addition to addressing this current lack of studies, future research should focus on high-quality studies with long-term follow-ups. Only in this way is it possible to take a closer look at PA promotion in VET, to draw clear conclusions about the effectiveness of studies, to make recommendations for practical use, and, thus, to answer more precisely the question of what we know about physical activity interventions in VET.