Move for 3 minutes every half hour

Why long stretches of sitting add up

Long, unbroken sitting is a normal part of many workdays. Studies that follow people have linked more sitting to less healthy markers such as waist size, blood sugar and blood fats. In one Australian study, 168 adults wore movement sensors for a week. People who broke up their sitting more often tended to have smaller waists and healthier blood fats and blood sugar, even when their total sitting time was the same.

That finding is the idea behind three minutes up, every half hour. It needs no gym, no change of clothes and no extra hour in your day.

How a short break helps your muscles

When your leg muscles contract, they pull sugar out of your blood to use as fuel. Working muscles can do this with less help from insulin, the hormone that moves sugar into your cells. Your thigh, hip and calf muscles are the largest in your body, so using them makes a measurable difference.

When you sit still for long stretches, these muscles do very little. More of the sugar from your last meal then stays in your blood for longer. Brief, frequent movement keeps the muscles taking up sugar through the afternoon.

What the lab studies found

In a 2016 trial, researchers in Australia brought 24 inactive adults with type 2 diabetes into a lab for three 8-hour days. On one day they sat the whole time. On the others, they stood up every 30 minutes for 3 minutes of light walking, or for 3 minutes of half-squats, calf raises and knee raises. Both kinds of break lowered blood sugar after meals by close to 40% compared with sitting all day, and insulin was lower too.

An earlier trial found something similar in 19 overweight middle-aged adults without diabetes. Two-minute walking breaks every 20 minutes lowered blood sugar and insulin after a sugary drink compared with unbroken sitting. A 2020 review that pooled many of these lab studies found the same direction of effect on average. The limit is that most studies lasted a single day, with small groups, often of people with overweight or diabetes. How much the benefit adds up over years of ordinary life, or how large it is for lean, active people, isn't known yet.

Fitting it into your workday

A repeating timer works better than memory, because time slips by when you focus. Start it when you sit down to work, and when it goes off, stand up before you check anything else. Walk to refill your water, climb a flight of stairs, or do the moves from the trial beside your desk. Your colleagues may glance over at the calf raises once or twice, and then they will stop noticing. If you work from 9 to 5, three minutes up, every half hour comes to about 15 breaks, or roughly 45 minutes of light movement spread across your day.

People often ask whether every half hour is really necessary. The trials used breaks every 20 or 30 minutes, so on a packed day a break every 45 minutes still interrupts your sitting, and a minute of marching on the spot counts. These breaks sit alongside the 150 minutes a week of moderate activity that health guidelines recommend. If you miss one, take the next without trying to make it up. After a few weeks, you become someone who stands up when the timer goes, without a second thought. If you have diabetes or take medicine that lowers blood sugar, ask your doctor how this fits your care plan, and see a physiotherapist if squats cause knee or hip pain. Which call or meeting tomorrow could you take standing up?

References

• Dempsey, P. C., et al. (2016). Benefits for type 2 diabetes of interrupting prolonged sitting with brief bouts of light walking or simple resistance activities. Diabetes Care, 39(6), 964-972. doi.org/10.2337/dc15-2336
• Dunstan, D. W., et al. (2012). Breaking up prolonged sitting reduces postprandial glucose and insulin responses. Diabetes Care, 35(5), 976-983. doi.org/10.2337/dc11-1931
• Healy, G. N., et al. (2008). Breaks in sedentary time: beneficial associations with metabolic risk. Diabetes Care, 31(4), 661-666. doi.org/10.2337/dc07-2046
• Loh, R., et al. (2020). Effects of interrupting prolonged sitting with physical activity breaks on blood glucose, insulin and triacylglycerol measures: a systematic review and meta-analysis. Sports Medicine, 50(2), 295-330. doi.org/10.1007/s40279-019-01183-w