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, these available studies are of poor quality. Ensuring high study quality while simultaneously taking local requirements and conditions into account is particularly difficult in real-world settings . Accordingly, methodologically complex and comprehensive studies are necessary to better examine interventions’ effectiveness in the VET field . 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 VET in European countries, such as the Benelux and Scandinavian countries or, in particular, Germany . However, pursuing higher education by enrolling in colleges or universities is the most common pathway after graduating from high school in the U.S. . 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 [30, 32, 34]. In contrast, none of the five top-down interventions that measured psychological factors indicated positive effects for this outcome [27, 28, 31, 33, 35]. Out of a total of six studies using top-down interventions, four reported significant improvements in PA level, physical fitness, and/or physiological parameters [28, 29, 31, 35]. According to this, top-down interventions seem to improve outcomes on the physical level. In terms of existing literature, “traditional” interventions designed using a top-down approach have shown limited success and are criticized for their low long-term sustainability [39–41]. A possible reason for these interventions’ failure might 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 of the target group and facilitating the intervention’s sustainability [40, 42, 43]. In our case, we cannot estimate the long-term effectiveness and sustainable implementation of the interventions, as no long-term follow-ups and reports on the continuation and anchoring of the interventions exist. Therefore, it is not yet possible to generalize which approach is more appropriate, and the tendency for bottom-up approaches to improve outcomes on psychological level and top-down approaches on the physical level needs to be investigated in further studies. In studies like this, recommendations for the intervention research process made by van Sluijs et al. [43, 44] also should be taken into account. The authors report an apparent willingness among adolescents to increase PA by expressing the desire to do more types of PA more often. In reality, this intention often fails due to poor attainment. Therefore, it is necessary to transform this enthusiasm into effective PA promoting interventions . Active engagement in the form of participatory or co-creational approaches could be a possible key to success in developing acceptable and attractive interventions .
Recent literature recommends multi-component interventions that combine various measures to promote PA, e.g., behavioral, educational, and/or environmental elements [14, 42, 45]. In particular, combining individual and environmental changes also is acknowledged in other studies, as effective behavioral changes in individuals require supportive policies and environments [46, 47]. Although our data are not strictly conclusive, the two studies showing significant effects in PA level and psychological factors [30, 34] 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 include offering various PA programs, providing PA equipment, and conducting workshops for teachers as multipliers 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 might 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 could lead to greater health benefits through lifestyle changes, not just a single behavior [48, 49]. However, in practice, such multi-behavioral interventions have proved to be an obstacle to success [14, 50, 51]. 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 [29, 32], while the only two studies that showed no significant effects also comprised multi-behavioral interventions [27, 33]. 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 intervention effectiveness .
Against this backdrop and our review’s results, the VET field seems to be promising for the implementation of PA promoting interventions, as many young people can be reached and a time and organizational framework is 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. Nevertheless, regarding the results from van Sluijs et al. [43, 44], 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 developing and implementing PA interventions in VET, high quality studies with long-term follow-ups conducted in real-world settings are needed.
Our review’s limitations are influenced by the number and quality of the included studies. First, we limited our search to studies published in English and German language and did not search for grey literature. We might have been able to find some studies without these restrictions, but we believe that we found the core studies through our extensive search. Second, we identified some weaknesses in the assessment of study quality using the EPHPP tool. The rigid scoring system may not always distinguish more robust studies from weaker ones. In particular, the lack of blinding was often the crucial factor for the studies’ weak global ratings. This is in line with other studies that have reported on the challenges of blinding in behavioral interventions [52, 53]. Finally, due to the small number of included studies, overall weak study quality, and heterogeneity of outcome measures, we were unable to conduct a meta-analysis. Thus, it should be taken into account that the conclusions on the linkage between intervention characteristics and intervention effectiveness presented in this systematic review are based on a descriptive, rather than a quantitative, analysis.