Thirty minutes' exercise won't counteract sitting all day, but light movement helps
It's recommended we do at least 30 minutes of exercise a day—or 150 minutes a week—to stay healthy. But 30 minutes accounts for just 2% of the day. And many of us spend most of the rest of the time sitting.
Research shows that sitting can be bad for our health in many ways—with some even suggesting it's as bad for us as smoking. And our new study has revealed that 30 minutes of daily exercise is not enough to overcome the health risks of sitting too much. But we also revealed that with the right balance of time spent exercising and moving, it may be possible to counteract the negatives of sitting.
We combined data from six different studies from the UK, US and Sweden, looking at a total of over 130,000 adults. Each of the studies used a physical activity monitor (like a Fitbit) to measure a person's movements and sitting time throughout the day. Each study then followed the participants for an average of four to 14 years to track whether any participants died.
As expected, we found that 30 minutes of daily exercise decreased the risk of early death by up to 80% for those who also spent less than seven hours a day sitting. But it didn't have the same effect for people who spent between 11 and 12 hours a day sitting. In other words, it's not as simple as checking off the exercise box on the to-do list. A healthy lifestyle requires more than 30 minutes of exercise if you spend a lot of time sitting.
For those who sat a lot, 30 minutes of daily exercise would only lower risk of early death by 30% if combined with four to five hours of light movement a day (such as shopping, cooking, or yard work) – spending less than 11 hours sitting total. We can think of this mixture of light activity, exercise and sitting as a "cocktail." And when it comes to living an active lifestyle, there are different recipes you can choose to to get the same benefits.
For example, one person might exercise daily for 30 minutes, move throughout the day for about six hours doing activities like housework or walking to work, but spend around ten hours a day sitting. They would have the same risk of death as someone who exercised 55 minutes daily, moved throughout the day for about four hours, and sat for about 11 hours. In other words, different combinations of exercise and movement can be used to offset the harms of sitting.
Our findings provide new insights on what constitutes a healthy and active lifestyle. For decades, scientists have studied the health benefits of exercise—but this research has largely ignored the fact that how you spend the rest of the day also matters. Instead of the recommendation that everyone should strive to achieve 30 minutes of daily exercise, our results show physical activity recommendations can been more personalized. People can adopt a mixture of activity that works best for them.
For many of us, our jobs require us to sit for eight hours or more a day. But when you get home, exercising for one hour and doing light activities for a few hours in the evening (such as housework or yard work) could still yield health benefits. If you're a stay-at-home parent who's typically too busy to get to the gym, moving around throughout the day while doing essential tasks (such as playing with the kids or putting away groceries) can also improve your health.
The caveat, however, is that our study found that six minutes of light activity was equivalent to one minute of moderate to intense exercise. So you would need to do three hours of light activity to yield the same benefit as 30 minutes of exercise.
While our study adds important new insights about the ideal balance of movement, we are missing one ingredient: sleep. It's unclear if the health benefits of exercise and movement are the same if you don't get enough sleep. As well, key questions on how to spend your day—like whether you should wake up 30 minutes earlier to exercise—still need to be studied.
Ultimately, our findings show that a healthy and active lifestyle is more than just exercising for 30 minutes, and that there are many different ways of achieving better health and longevity. While exercise still provides the best "bang for your buck" in terms of the amount of time required, our findings are still good news for people who may not have the time, ability or desire to exercise. The road to an active lifestyle is more accessible and achievable than we thought—and is not just for gym regulars.