A new study has some good news for people who spend a lot of time sitting:

Thirty to 40 minutes a day of moderate to vigorous physical activity can offset up to 10 hours of sedentary behavior.


For years, we’ve been told that any amount of sitting is bad for us. Creative headline writers went as far as to say “sitting is the new smoking.”

That’s obviously BS, as this 2018 study in the American Journal of Public Health showed.

But just because sitting isn’t as dangerous as smoking doesn’t mean it’s healthy.

The study showed that people who spend the most time in sedentary activities have nearly twice the risk of type 2 diabetes, compared to the most active individuals, and an increased mortality risk of about 20 percent.

The open question for fitness professionals:

What do we tell clients whose work requires them to sit for eight to 10 hours a day? Are they just SOL?

We now have an answer.

What’s new in this research

The new research in the British Journal of Sports Medicine is a meta-analysis combining nine studies from four countries, with more than 44,000 participants who were followed for up to 14 years. About two-thirds were women, and the average age was 65.

More than 3,000 study subjects died, giving the researchers a lot of mortality data to work with.

But unlike previous studies, which were based on self-reported data, these subjects wore activity trackers, like Fitbits.

Here’s what the researchers found, when they combined the data:

  • Those who spent the most time sitting had higher mortality rates, no matter how much exercise they got, compared to those with the least sedentary time.
  • Those who got the most moderate to vigorous physical activity had lower mortality rates, no matter how much time they spent sitting, compared to those who got the least exercise.

In other words, exercise mostly offsets the health risks of sitting, but doesn’t eliminate them completely.

The sweet spot is 30 to 40 minutes a day of moderate to vigorous physical activity, which can be anything from walking the dog to training for a marathon.

The danger zone is more than 10 hours a day of sitting. No amount of exercise can completely offset that much inactivity.

What it means for your clients

Is this a message you can sell to your clients? Can you use this data to convince them to exercise more or sit less?

It probably depends on how you frame it.

“For health behaviors, risk awareness does not work well,” says frequent PTDC contributor Justin Kompf, whose doctoral studies focus on behavior change to promote physical activity. “A gains-framed message would be more motivating.

“Still, I don’t run into many people who would be motivated to get out there and move more if I just told them it would prolong their life.”

A better tactic, Kompf says, would be to use the data to track improvement. You could put clients in competition with themselves or with each other, with the goal of measuring and ranking improvement over time.

The takeaway

The bottom line for fitness professionals:

Motivating clients to exercise is hard. Especially when gyms are closed and they’re forced to work out at home.

It’s equally hard to get them to sit less when they’re home all day and have few non-sedentary options.

You can use this study to give them two new goals: move more, sit less.

If they’re willing to use an activity tracker, you can challenge them to show improvements over time in both areas, and perhaps even turn it into a competition with other clients.

After all, it is a matter of life and death.