Several large scale international epidemiological studies have found a substantial link between sitting for prolonged periods Stem Cells inhibitor each day and negative changes in metabolic health, increased risk of all-cause mortality, and cardiovascular disease (Stamatakis et al 2011, Dunstan et al 2010). Importantly, these effects remain even when adjusted for other cardiovascular disease risk factors (Dunstan et al 2010). While research into the cause and effect of sitting time on cardiovascular disease risk is in its infancy, the epidemiological findings are convincing enough for

the National Heart Foundation of Australia to have recently launched an information sheet recommending that people should aim to reduce the amount of time they sit each day (National Heart Foundation of Australia 2011). Alzahrani and colleagues suggest that, because the total duration of sitting time was similar between stroke survivors and agematched controls, stroke survivors are no more at risk of recurrent stroke. This interpretation may be incorrect.

First, it is not the total time spent in sedentary behaviour (sitting or lying) each day that is of primary importance, but the way in which this time is accumulated. Healy and colleagues (2008) found that breaking buy trans-isomer up sitting time with frequent, short bursts of light activity (such as standing and walking for a few minutes) was significantly associated with reduced cardiovascular disease risk. Importantly, this finding was independent of either total daily sitting time, or time spent in moderate to vigorous physical activity. The paper by Alzahrani et al (2011) reports that stroke survivors

underwent few transitions (changes in body position) per day compared to controls. It would be of interest to know whether this means that stroke survivors sat for longer periods oxyclozanide at a time and accumulated their active time in fewer bouts per day. If so, this may lead to an increased risk of cardiovascular disease, including further stroke. Second, both the stroke survivors and control participants in this study accumulated more than seven hours of sedentary time during the day, which was more than half of the time they were observed. While we do not yet know how much sitting time is too much, sitting for seven hours a day, particularly if this time is accumulated in long bouts, may well be placing both stroke survivors and healthy people at an increased risk of cardiovascular disease. More research is needed to investigate how we can encourage stroke survivors to increase incidental daily activity levels in a sustainable way, and to determine if changes in sitting time behaviour will result in reduced cardiovascular disease risk for individuals. “
“We thank Dr English for her thoughtful comments on our paper (Alzahrani 2011).