27 March 2012
As evidence accumulates about the dangers of sedentary behaviour – particularly prolonged sitting, a small, experimental one-day study published last month has found that interrupting sitting-time with short, two-minute bouts of walking lowered postprandial (after meals) glucose and insulin levels among the 19 participants – all of whom were overweight and between the ages of 45 and 65 years, but did not have type 2 diabetes.
In fact, the results showed that taking two-minute breaks to get up and walk around every 20 minutes reduced postprandial glucose and insulin levels by as much as 30 per cent.
Interestingly, the improvements in the study were the same regardless of whether participants were walking at light intensity (a stroll) or moderate intensity (aiming for 6.4 km/hour).
“Quit the sit,” is something of a mantra for study author, Associate Professor David Dunstan, head of the Physical Activity Laboratory in the Division of Metabolism and Obesity at Baker IDI Heart and Diabetes Institute. He and his colleagues are investigating the impact of regularly interrupting sedentary periods with short bouts of walking.
Professor Dunstan says that muscle contraction is involved in regulating glucose metabolism and removing glucose from the blood stream; and the team has collected muscle tissue and fat tissue from the participants in this study which will be used for further research to try to understand the mechanism.
The researchers say lowering postprandial glucose and insulin “suggests both increased insulin sensitivity and reduced insulin secretion,” and point out that the reduced insulin secretion is “consistent with preservation of pancreatic beta cell function.” (Beta cells are the cells that produce insulin in the pancreas.)
They chose to have participants take three breaks per hour because previous research had shown that this put people into a more favourable health profile. Additional research needs to be done to learn more about the dose-response relationship, and to address questions about whether merely standing up will provide a similar benefit, since it still involves muscle contraction.
Professor Dunstan says work-place cultures need to change to make standing up and moving around more socially acceptable – especially in situations such as meetings where people tend to sit for long periods.
He says simple changes such as taking a walk during lunch, standing at a high bench during lunch breaks, or using a height adjustable desk are all practical ways to break up sitting. “Within our OH&S guidelines there are general recommendations that computer-based workers should take a break from their computer screens every 30 minutes. These are based on concerns about repetitive eye strain.
But we should also include some physical movement with the break, not just turning your eyes away from the screen,” he says.
Last Reviewed: 27 March 2012