Exercising for 30 minutes on most days is supposed to keep you in good health. But research suggests that’s not enough if you spend a lot of time sitting.
If you’re sitting down while you read this, you might want to stand up.
Research now shows that sitting for long periods can increase your risk of a range of health conditions and premature death.
This is not only terrible news for those of us with a desk job; it’s a grim warning for all. Our increasingly sedentary lifestyle means we all spend a lot of time on our backside – we sit when we drive our cars, eat our meals, watch TV, use a computer (or any other of the screens we regularly use), read from a book, use the phone, catch up for a cuppa with our friends and the list goes on.
But here’s the kicker: even if you are meeting – or even exceeding – the Australian Government’s physical activity recommendations, you still need to move more. (These guidelines recommend you get 30 minutes of moderate-intensity exercise per day most days of the week.)
Dr Alicia Thorp from the Baker IDI Heart and Diabetes Institute is currently researching the effects of standing and sitting in the workplace, she says regular exercise is not enough to counteract the amount of sitting many of us do.
“People can meet the physical activity guidelines and do a 30-minute run every day, but if they’re spending 10 hours of the day sitting, then it is not going to wipe out the effect of all the sitting,” Thorp says.
The bottom line, she says, is that we all need to move as much as you can throughout the day.
“Stand up. Move more, more often. These should your mantra for daily living”.
How much sitting do we do?
Sitting and lying down are known as sedentary behaviours that require a very low level of energy output. (Activities are often measures in METs – Metabolic Equivalent of Task – sedentary activities range between 1 and 1.5 METs, walking at a moderate pace ranges between 3-3.5 and jogging is about 7.)
Research suggests that most of us are spending more than half of our day being sedentary. The Australian Diabetes, Obesity and Lifestyle study found adults spend:
- 57 per cent of their time engaged in sedentary activities
- 38 per cent of their time engaged in light intensity activities
- about 5 per cent of their time doing moderate-to-vigorous activity.
Interestingly, these findings are based on data collected using devices known as accelerometers, giving researchers a more objective measure of how sedentary – or active – people are.
What the research shows?
The growing body of research into sedentary behaviour clearly shows that prolonged sitting is a risk factor for metabolic syndrome, heart disease, type 2 diabetes, some cancers, obesity and early death.
A recent University of Sydney study, looking at more than 222,000 adults aged 45 and over, found that men and women who sat for 11 hours or more a day had a 40 per cent greater risk of premature death, than those who sat for less than four hours.
Another recent US study, found adults who were most sedentary (i.e. were sedentary for more than 10.8 hours a day for men, 10.1 hours a day for women) had more than three times the risk of premature death compared to those who were least sedentary (i.e. were sedentary for less than 7.6 hours a day for men, 7.2 hours a day for women).
While a 2010 Australian study compared people who watched television for four hours a day to others who only watched for less than two hours a day. The researchers found those who watched for more than four hours a day had an increased risk of premature death of 46 per cent. This was not because of the standard of entertainment on offer, but because watching TV tends to be the most common sedentary leisure activity. (It’s been estimated that for every hour of television you watch over the age of 25, your life expectancy is reduced by 22 minutes.)
Why is sitting so bad?
Researchers are still trying to understand exactly why it is that sitting has such a deleterious effect on our health.
But Thorp says it appears to be related to the enzymes that help to regulate blood fats and sugars, which are released as certain muscles contract when you stand.
“Muscle contraction is a major contributor to many of the body’s regulatory processes, such as breaking down glucose, and when we sit our leg muscles are essentially inactive,” she says.
“Loss of local muscle contraction during prolonged sitting is shown to ‘slow down’ the production and activities of key enzymes involved in removing fats from the blood and exercising won’t prevent this ‘slowing down’ from occurring.
“It is also shown to reduce the uptake of glucose from the blood stream into skeletal muscle.”
However, you only need to stand up or take a short walk in order for your leg muscles to contract, which can help prevent those key enzymes from being switched off.
“Our group recently reported that breaking up prolonged sitting every 20 minutes with a two-minute walking break ameliorates the adverse effects,” she says.
Get out of your chair
However, Thorp acknowledges standing up all day is not necessary.
“We don’t advocate that people spend the whole day standing,. There is literature around that shows that standing all the time can be bad for you,” she says.
“The message we want to get out is that you don’t have to spend the entire day standing, but you do want to break up your sitting time.”
Thorp recommends sitting for no more than 30 minutes at a time and standing as much as possible throughout the day.
Organisations, such the Australian Heart Foundation and the American College of Sports Medicine, have released recommendations about the need to reduce the time we spend in our chairs and what changes you need to make.
Some of these include:
- standing up whenever you use the phone
- doing household chores when watching television, e.g. folding clothes and ironing
- standing or walking for meetings
- walking or riding a bike to work, school or the shops
- when driving park your car further from your destination and walk some of the way
- getting on/off public transport one stop earlier and walk the rest of the way
- standing up when using public transport, if possible.
You can view the original ABC Health & Wellbeing article here.
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