This study evaluated preliminary findings of longitudinal randomized controlled trial (RCT) to address sedentary behaviour and cardiometabolic risk markers in a cohort of South African office-based workers. It is pertinent to note that this study solely concentrated on addressing sedentary behavior during work hours, and did not encompass any other aspect of physical activity or exercise. The current study’s findings are similar to those of previous short-term RCTs investigating the sedentary behaviours of office workers (9, 10). These studies have shown that modifying the workplace through the introduction of a height-adjustable sit-to-stand workstation intervention resulted in significant reductions in sedentary behaviour in the workplace in high-income countries. However, there is paucity of evidence on workplace interventions to address sedentary behaviour and related cardiometabolic outcomes in LMICs (5). Our study supports the use of height-adjustable sit-to-stand interventions in reducing sedentary behavior and improving cardiometabolic outcomes among South African office-based workers.
An important finding of this study is that small and trivial improvements were observed in most cardiometabolic risk markers. In agreement with our findings, a systematic review investigated the effectiveness of sedentary behaviour reduction workplace interventions on cardiometabolic risk markers (4, 7, 12). This suggests that long-term sedentary behaviour interventions are associated with significant effects on cardiometabolic risk markers. However, it is not clear which cardiometabolic risk markers improve with sedentary behaviour interventions (4, 7, 12). Previous reviews have shown that both short (≤ 12 weeks) and long-term (≥ 3 months) interventions are effective in breaking prolonged vocational sitting (9, 10, 12). This suggests that reducing sitting time alone may not be enough to significantly improve health outcomes. As such, there is a need to consider other factors that are crucial for maintaining overall health such as diet and exercise.
Existing literature has shown that interventions for reducing sedentary behaviour have small improvements in selected health outcomes of office-based workers (7). For instance, in the current study, we observed small effects on health outcomes such as BMI (-0.11, d = 1.07) kg.m2, blood pressure (-0.26, d = 1.10) mmHg, and cholesterol levels (0.11, d = 0.07) mmol/L− 1 in 3 months. It is important to note that the changes observed in this study were relatively small and may not be clinically significant (7, 12). Our results provide valuable insights into the potential benefits of reducing occupational sitting time in office-based workers. Further research is needed to determine the long-term effects of reducing sitting time on health outcomes and to identify the most effective interventions for achieving sustained behaviour change in the workplace, particularly in LMICs such as South Africa. Strengths of this study include an RCT study design and objective measures of both movement and cardiometabolic outcomes.
Limitations
There are important implications to these preliminary findings that should be recognized. More than 60% of the participants dropped out of the current study which reduced the size of the study sample and may limit the generalizability of the findings Another limitation of the study was that it was conducted during the Covid-19 pandemic when movement restrictions and a shift to full remote work and closing of companies were imposed on South African workplaces, which may have influenced the large drop out rate.