Most of us sit in front of computers to work and play for extended stretches of time. That’s dangerous. Over the past several years, studies have shown that sitting for long periods, called sedentary time, is associated with harmful conditions such as obesity, high cholesterol, and high blood sugar. One recent review of several of these studies found that sitting for more than eight hours a day without physical activity is as bad for you as being obese or smoking. And since the average adult in developed countries spends nine to 10 hours in an office chair, many have tried to solve the sitting problem with standing desks or treadmill walking while on the phone. Or the sitters set timers to indicate when to stand and move about.

But all that can be a hassle.

Good News for Long-Term Sitters

A new study from a collaboration of researchers in Norway, Sweden, and the United States finds that you can safely sit down if you average more than 22 minutes of moderate-to-vigorous physical activity (MVPA) per day. That amount of MVPA was found to eliminate the health risk of sedentary time. That amount of MVPA corresponds to the lower level of MVPA recommended by the World Health Organization, 150 to 300 minutes of moderate-intensity exercise per week.

The new study, which is published in the British Journal of Sports Medicine, analyzed data from four previous studies involving close to 12,000 adults age 50 and over. All study participants had a minimum of four days that included 10 daily hours monitored for activity for at least two years. To measure sedentary and MVPA times, the studies reviewed used a type of fitness tracker worn on the belt called a hip accelerometer. This device measures the force of forward movement (acceleration).

The researchers wanted to find out how both sedentary time and MVPA were associated with mortality. Acceleration data can be used to measure MVPA, but for people without the data, moderate exercise can be defined as exercise that increases breathing rate without causing shortness of breath, works up a mild sweat in about 10 minutes, and does not affect talking. Vigorous exercise makes you a bit short of breath, works up a quicker sweat, and makes it hard to talk normally.

22 Minutes Makes a Big Difference

During the study period, 805 people died (about 7 percent). After adjusting for other mortality risk factors such as sex, obesity, smoking, cardiovascular disease, cancer, and diabetes, these were the key findings of the study…

  • Getting less than 22 minutes of MVPA per day, along with more than 12 hours of sedentary time, was associated with a 38 percent higher risk of death compared to eight hours of sedentary time.
  • Getting more than 22 minutes of MVPA was associated with a lower risk of death no matter the sedentary time.
  • Ten more minutes of MPVA per day was associated with a 15 percent decreased risk of death in people with less than 10.5 hours of sedentary time and a 35 percent lower risk in people with more than 10.5 hours of sedentary time.

Long sedentary time may be a risk factor for death because it allows large muscles and heart muscles to become weak, called deconditioning. When we’re deconditioned, it becomes harder to exercise and stay fit. Deconditioning has also been associated with poor mental health, injuries, and poor sleep.

But you can reduce your risk. The research team concludes that even small amounts of MVPA may be an effective strategy for reducing the health risks of sedentary time.

Source: Study titled “Device-Measured Physical Activity, Sedentary Time, and Risk of All-Cause Mortality: An Individual Participant Data Analysis of Four Prospective Cohort Studies,” led by researchers at Arctic University of Norway, Tromsø, published in the British Journal of Sports Medicine.

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