The effect of an e-health intervention designed to reduce prolonged occupational sitting on mean arterial pressure

Prevalent in Australia are a range of workplace health and wellness interventions designed to reduce or eliminate cardiovascular disease (CVD) risk factors by advocating an increase in physical activity. The inclusion of increased physical activity is largely in response to evidence of an inverse relationship between habitual physical activity and blood pressure (BP).1 Yet, recently, prolonged sitting has been identified as being independent of cardiovascular fitness levels.2–4 Thus, regardless of voluntary exercise levels, desk-based workers who sit for more than 6 hours per day at work5,6 might still be exposed to CVD risk.7,8 In response, there has been an increased effort to regularly break occupational sitting periods9,10 by integrating regular short bursts of non-exercise physical activity (NEPA) throughout the workday.11 There is evidence that increasing NEPA results in positive change to some physiological functions,12 yet there are no data of the effect on BP. Thus, the aim of the researchers in this study was to assess the effect of NEPA on BP within a workplace setting. Regular moderate-to-vigorous physical activity is widely regarded as a method to reduce hypertension.13,14 The evidence indicates that dynamic physical activity (moderate-to-vigorous) results in BP changes in individuals who are hypertensive. Nevertheless, there is some evidence that lower-intensity physical activity can also reduce BP in borderline hypertensive individuals. Ishikawa-Takata et al15 reported that one session of 30 to 60 minutes per week of physical activity resulted in significant reductions in both systolic and diastolic BP at rest. Similarly, Ross and McGuire12 reported that incidental NEPA accrued sporadically throughout the day was associated with increased levels of cardio-respiratory fitness in inactive, abdominally obese men. Given the difficulties associated with adherence rates in voluntary aerobic exercise programs that use traditional guidelines16 and the lack of data that cardiovascular fitness levels might not reduce CVD,17 the use of NEPA has become an attractive proposition for workplace health and wellness interventions. On the basis of this, we subjected desk-based employees to a protocol of regular short bursts of NEPA to interfere with prolonged sitting habits to ascertain any effect such activity might have on employees’ BP. Rather than analyze systolic and diastolic BP variables, it was determined that mean arterial pressure (MAP) would be a better measure because it provides a better representation of the average pressure throughout one cardiac cycle.18,19 Among the few studies that have addressed the effect of MAP on CVD, Dyer et al20 and Mitchell et al21 found that MAP was strongly associated with CVD risk and increases in myocardial infarction. Measurements for MAP that are greater than 110 mmHg in adults are considered too high and can impact negatively on individual health.22 We hypothesized that desk-based employee's exposed to regular short bursts of NEPA would significantly reduce their MAP, whereas control participants who were not prompted to perform NEPA during the workday would not.