This pilot study aimed to evaluate the effects from a five-week video-based intervention including videos with exercises that can be done directly at the individual desk on HEPA, PAHCO and HRQoL in office workers.
The repeated measures ANOVAs indicate that there is a decrease in total HEPA after the intervention and at follow-up, but not significantly. Although there is an initial increase in sports activity, it decreases significantly at follow-up. The results are in line with another study in which 328 office workers underwent a three-week workplace health promotion programme based on the PAHCO model (18). The study measured leisure-time physical activity (LTPA) including sports activity, but excluding light PA and active commuting. Postintervention, LTPA witnessed an initial increase, but it decreased significantly after six and 18 months. However, the study we conducted had less guided HEPA during the intervention period than the study from Blaschke and colleagues, with a minimum of 135 minutes per day over three weeks. Regarding only sports activity, the outcomes show a comparable pattern – an increase after the intervention, followed by a decrease during the follow-up period. Another study (35) also showed that PA increased after an intervention, but then decreased at the six-month follow-up. Nevertheless, a subsequent 13-month follow-up showed an increase in PA. The authors attributed this effect to a seasonal pattern and the first follow-up taking place during the winter season. This could be applicable to our research as the three-month follow-up was conducted in January and February, and the questions about cycling to other activities and gardening were accompanied by considerably less PA than in the baseline survey in August/September. A scoping review (36) examining the impact of seasons and weather on PA and other related factors found evidence that people tend to be more active in the summer than in the winter. This finding highlights the need to consider such seasonal variations when designing and implementing PA interventions and interpreting the results.
The total PAHCO score increases significantly after our intervention, which is mainly due to the significant increase in control competence. Movement competence and self-regulation competence increase as well, but not significantly. Our results are consistent with Blaschke's study (18): PAHCO significantly increased and remained stable after the 18-month follow-up in their intervention. The authors attributed this to the high amount of guided HEPA and the face-to-face design of the intervention. Their design is very different from our study: They conducted at least 135 minutes of supervised PA per day over 15 days. The amount of supervised PA in our study was much lower, with 10 sessions of 5 minutes each, and completely digital. Nevertheless, in our study, PAHCO significantly improved, particularly in the area of control competence. One reason for this could be that the entire development of the intervention was based on the PAHCO model. This implies that PAHCO was advocated not only by guided HEPA but also by every aspect of the intervention: the videos as the primary intervention content, the PA diary and the daily prompts. The intervention occurring within the day-to-day work of office workers enabled them to practically test and apply the acquired strategies in the relevant context, obviating the need for transfer from an experiment-like environment to everyday life. In another study, aimed at ninth-grade students, Rosenstiel et al. (37) conducted six 90minute Physical Education lessons, in which the content of two scales of the PAHCO model was delivered through running or gameplay interventions. Both theory and practice were incorporated into the sessions. A significant increase in both PAHCO scales was observed in the gameplay intervention group after the intervention, but there were no significant differences at follow-up after 8–12 weeks (20). This demonstrates the similarity with our study that PAHCO can be influenced by interventions. Nonetheless, our research showed that the PAHCO scores remained stable over a longer period of time. Similar outcomes were found by Blaschke et al. (18), who attribute this difference to a lower stability of PAHCO at a younger age.
The mental dimension of HRQoL decreases significantly after our intervention, but returns to almost baseline levels at follow-up. These results are in contrast to those of Blaschke et al. (18): immediately after their intervention, HRQoL increases in both dimensions and then decreases slightly after 6 and 18 months, but still remains above the baseline value. The design of our study may account for this difference: while Blaschke and colleagues took a threeweek break from work, our intervention was integrated into everyday working life. Although this may have been beneficial for the development of PAHCO, as participation in the study took place in addition to normal daily obligations, it may have been perceived as an additional task and thus had a negative impact on the mental dimension of HRQoL.
The PA diary was considered the least helpful in increasing PA in our study. Self-monitoring, such as keeping a PA diary, is a recognised behaviour change technique and listed in Michie's taxonomy as a helpful intervention component (38). However, a recent metaanalysis highlighted a negative moderating effect of self-monitoring on PA in adults with overweight and obesity (39). Although our study did not investigate the direct association between the PA diary and HEPA, the evaluation of the diary reveals that respondents did not perceive it as positively as other intervention components. Thus, more information is required on how to design and incorporate a PA diary within the intervention to enhance participants' perceptions of its usefulness.
In our study there were correlations between the total PAHCO score and sports activity, but not Leisure Time/Transportation PA. Blaschke et al. (40) found a positive correlation between PAHCO and LTPA, which was not found in our study, except for sports activity. Blaschke and colleagues suggest that an increase in PAHCO leads to an increase in LTPA and thus to an improvement in health in the long term. However, conceptual differences in the measurement of PA may lead to differences in results, as Blaschke et al. only measured LTPA and did not include active commuting, for example.
There were positive correlations between control competence and Anatomy, but not between control competence and Health knowledge to go in our study. The sections on Anatomy and Health knowledge to go were the content of the intervention that most closely addressed control competence. The positive correlation between control competence and the rating for Anatomy supports this, although the absence of correlation with Health knowledge to go contradicts this. However, the measurement focused not on knowledge gain, but on the subjective helpfulness of increased exercise. One method of assessing the impact of health education is to administer a health-related fitness knowledge (HRFK) test, as Volk et al. (41) did with pupils. This tool can demonstrate intervention-related improvements in HRFK among ninth-graders. Nevertheless, it has not been validated with other age groups, so it is not clear whether it is suitable for adult office workers. Moreover, the test comprises 33 items, some of which are open-ended questions, making it relatively long. Volk and colleagues have highlighted that other assessments lack standardised definitions of HRFK, as well as low reliability and validity. However, potential correlations between PAHCO, HEPA and HRFK should be investigated in future studies.
Lastly, there was a positive correlation detected between the scores of the Prompts and the Homepage with Leisure Time/Transportation PA. This suggests that the two components of the intervention provided an encouragement to engage in low-threshold exercise. MacPherson and colleagues (42) found that people at risk of developing type 2 diabetes were more likely to keep their PA diary for up to three days after a prompt. Prompts seem to increase awareness of PA, but are not intense enough to have an impact on sports activity. However, this is only a correlation and does not indicate a causal effect.
4.1 Strengths and limitation
To the best of our knowledge, this is the first intervention to address PAHCO and HEPA in a real-world setting with office workers. Because of the brief, video-based intervention, participation could be easily assimilated into the everyday work routine. After the intervention, PAHCO increased significantly and remained stable at the higher level three months later.
Further strengths arise from our use of the PAHCO questionnaire with all sub-competences, compared to previous studies (18). By using the BSA-F and converting PA minutes to MET minutes, it was also possible to measure HEPA, which is the conceptual outcome of the PAHCO model (17).
However, it is important to note the limitations of this study. The absence of a control group and randomization in the intervention plan means that the causal relationship between the intervention and HEPA and PAHCO cannot be established. Although a control group was initially planned, insufficient participation in the study meant that the results could not be statistically analysed.
Furthermore, whilst PA levels were measured using the BSA-F and the PA diary, they were not measured objectively, for example using an accelerometer. To prevent biased evaluations, combined measurement utilising different methods is advised (43). Unfortunately, only a small number of participants maintained a regular PA diary, therefore the BSA-F was used to assess and analyse PA. However, when evaluating other PA questionnaires, only moderate agreement with objectively measured PA was observed, therefore the findings should be interpreted carefully (44). As the baseline survey was conducted in the late summer and the follow-up survey was conducted in the winter, seasonal effects in PA cannot be excluded, as previously discussed (36). In future studies, PA should therefore be surveyed objectively and at different seasons.
An objective assessment of PA combined with an objective assessment of health outcomes could lead to a better understanding of the PA paradox (14) in the future. It is not possible to conclusively determine whether the PAHCO model is suitable for preventing the PA paradox in workplace interventions, as we did not determine whether the participants engaged in physical activity during their leisure time or at work, but the increase in PAHCO after the intervention is an initial indication that the model is suitable for planning PA interventions in the workplace.
Another limitation of the study is the very high dropout rate, with only 20% of participants completing all questionnaires. Face-to-face interventions have a retention rate of 75% (45), and web-based interventions have a retention rate of 50%, although the range here is very broad at 10–90% (46). A qualitative interview study is currently investigating the reasons for dropout (47).
In addition, the study was relatively short in comparison with other workplace PA interventions, with an intervention period of 5 weeks and a follow-up period of 3 months (13). Possible effects on both the HEPA and PAHCO sub-competence movement competence might be better achieved with a longer study duration.