22 minutes of exercise per day cancels out the impact of sitting down.
Experts have found that those who sit for long periods - such as in a desk job or watching TV - are more likely to die earlier but just a small amount of moderate-to-vigorous physical activity (MVPA) eliminates the risk.
Examples of moderate activity include very brisk walking, heavy cleaning such as washing windows and playing badminton.
The findings back up the UK chief medical officers' recommendation that people aim for 150 minutes of MVPA per week - about 21 minutes per day.
Edvard Sagelv, who led the study for the Arctic University of Norway, said: "In our study, we found that only those people doing more than 12 hours per day sitting had a higher risk of death.
"We are talking about any sitting behaviour – such as being in the office or watching TV for long periods of time.
"However, doing 22 minutes eliminated the higher risk of death from sedentary time.
"And, if doing more than 22 minutes per day, there was a lower risk of death overall. Basically, the more the better."