Most of us try our best to balance out the sedentary aspects of our lives with physical activity. But even the most active spend considerably more time sitting than moving. Data from accelerometers suggest most middle-aged and older adults spend 11 to 12 hours a day (65 to 75 per cent of time awake) sedentary and less than 30 minutes engaged in moderate to vigorous physical activity
Work and commuting account for much of our sedentary time. Though it’s possible to change some aspects of how much time is spent behind a desk, in a car or on public transportation, much of today’s workforce sits for the majority of day
Given our sedentary lifestyle, researchers have been trying to pinpoint exactly how much activity it takes to negate the health consequences of hours spent sitting. Don’t confuse the amount of time it takes to reduce the risk of chronic diseases like cardiovascular disease, diabetes and some forms of cancer with the metabolic, vascular and inflammatory consequences of too much time being stationary. It has long been postulated that 150 minutes a week of moderate to vigorous activity isn’t enough movement to conquer a lifestyle with high levels of sedentary behaviour.
The debate about whether even large amounts of exercise is effective at combating a sitting lifestyle is ongoing. In a recent article in Medicine and Science in Sports and Exercise, a team of Norwegian researchers analyzed the latest studies to see what volume of exercise it takes to mitigate the health risks of chronic sitters. Until recently, much of the research on the health benefits of physical activity has been based on self-reported data, so the Norwegian researchers prioritized studies with device-based measures of active and sedentary time to get a more accurate assessment of what a normal day looks like for most adults.
“Looking at the joint effects of these two behaviours is important because most people engage in both behaviours every day, so the effects of both should be considered when interpreting if moderate to vigorous physical activity can offset the negative health aspects of prolonged sedentary time,” the researchers said
Their findings suggest there is a threshold to shoot for if boosting your daily quota of exercise is easier than reducing the amount of time spent sitting
“While the specific doses of moderate to vigorous physical activity needed to fully offset the mortality risk from sedentary time is somewhat unclear, the collective evidence of a modifying effect of moderate to vigorous physical activity suggest that levels of moderate to vigorous physical activity close to the higher end of the current World Health Organization recommendations (150-300 minutes per week) fully offset the risks associated with important outcomes.”
Not everyone agrees. A group of Australian researchers question whether exercise alone can fully offset the health risks of high volumes of sedentary behaviour. They suggest that too much sitting can “blunt the expected metabolic benefits of exercise,” and that sedentary behaviour and physical activity “operate through partially distinct and interacting physiological pathways.”
“Sedentary behaviour may influence health both directly through its own adverse physiological effects and indirectly by reducing responsiveness to exercise,” the Australian researchers said
Despite their disagreement, there is some common ground with both sets of researchers agreeing that lifestyles including long periods of uninterrupted inactivity require more than the recommended 150 minutes of exercise per week to reduce the associated negative health consequences. Based on the most recent data, if you regularly spend long periods of sedentary time behind a desk or in front of a screen, you’ll need to aim for 40 minutes of exercise a day
Before you panic, it’s still not clear whether the exercise needs to be vigorous in intensity. There’s a strong suggestion that light physical activity, which is defined as the incidental movement that is part of your daily habits (house or yard work, walking, going up and down stairs etc.) can contribute toward the goal of a minimum of 40 minutes of daily activity
Bottom line if you sit a lot, try to break up long periods of inactivity with simple movement strategies that get you out of your chair. Many smart watches prompt you to move if they detect long periods of inactivity. They also calculate time spent being sedentary and active, which gives you a realistic picture of the degree of change you need to make to improve your long-term health
Work on cutting down on sedentary time by adding more movement breaks into your day. And on days when meetings are long and frequent and screen time is unrelenting, go for a walk at lunch and/or after dinner and try to hit the gym for a quick workout. Anyone whose day includes lots of sitting needs to set a loftier goal than just 150 minutes of physical activity a week if they want to counteract a 9 to 5 spent behind a desk
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