Changes in vascular function after a reduced sitting intervention

Over the last years, physical inactivity has been identified as the major cause
of death in Western society (2, 3). Despite recommendations for regular
physical activity and promotion of exercise programmes, still a large
proportion of the population does not meet these recommendations. Some years
ago, epidemiologic studies have identified the association between sedentary
behaviour (i.e. sitting and lying) and cardiovascular diseases or
cardiovascular(CV) risk factors. Importantly, the detrimental impact of sitting
time is not altered after correcting for exercise training time. Therefore, the
benefits from *reduce sitting time* and exercise training seem independent from
each other. Consequently, prolonged sitting is a logical target to improve
cardiovascular risk factors via reduced sitting time. The first short term
studies (i.e. hours and weeks) have revealed benefits in several CV risk
factors. In this study, we will explore the longer term effects of a reduced
sitting intervention on CV risk, and (cerebro)vascular factors.

In this intervention study we examine the effect of an 12-week reduced sitting
time intervention on cardiovascular function (i.e. changes in femoral artery
FMD) in subjects with an increased risk for cardiovascular disease. As a
secondary objective, we want to obtain insights in the cerebrovascular effects
of a reduced sitting intervention. Therefore, we will measure cerebrovascular
function and peripheral vascular function. In addition, we will investigate the
mechanism involved in mediating the impact of prolonged sitting on vascular
function by exploring measures of inflammation, NO-pathway and metabolism.

randomized controlled trial: stepped wedge design

12 weeks reduced sitting intervention: Subjects will wear a pedometer
throughout the day in order to record physical activity patterns. The device
identifies prolonged periods of sitting or physical inactivity, which will lead
to notification that the participant has to break up his/her sitting behaviour
to reduce sitting time.

Participants will report 9 times to the research centre (total of 26 hours)
over a period of 25 weeks to measure vascular function, and cerebrovascular
function. All vascular measurements will be non-invasive. Venous blood sampling
is associated with a very low risk. Taken together, the nature and extent of
burden and risks associated with the intervention and measurements are
negligible, whilst the study leads to significant insight into the health
benefits of reducing sitting time in a clinically relevant group. Moreover, the
measurements will also provide further mechanistic insight into the impact of
reducing sitting time on (cerebro)vascular health.