A new study out this week suggested that both sitting a lot overall and sitting for long, uninterrupted stretches can increase a person’s risk of all-cause mortality.

The study, published in the Annals of Internal Medicine, adds to evidence that sedentary lifestyles can increase health risks. However, the study aimed to push the conversation forward, not just look at how much time people spend sitting each day and what that does to health. The researchers also tried teasing apart patterns of sitting. The authors, led by researchers at Columbia University, hoped to address more nuanced questions, such as: if you have to sit all day for work, can you reduce your health risks by getting up every 30 minutes? Or, if you’re generally active, are there still health risks from a 10-hour Netflix binge each week?

The questions are good ones. Based on the study’s vast media coverage, health-conscious Americans are leaping for answers and specifics on the risks of our sedentary, modern lives.

But, sadly, this study doesn’t provide those answers or specifics. In fact, it’s kind of a flaming disaster. Like a junky old couch stuffed with crumbs, stale Cheetos, remotes from bygone TVs, and a random woodland creature between the cushions, this sitting study is crammed with red flags, limitations, and crippling weaknesses. It’s difficult to draw any conclusions.

Let's start with the money: It was funded in part by Coca-Cola

The study clearly mentions this in the text, and the authors note:

“The Coca-Cola Company had no role in the design, conduct, or analysis of the study or in the decision to submit the manuscript for publication.”

That may be true. But, it’s hard to look past the fact that this is exactly the type of health and nutrition research Coke wants. In fact, Coca-Cola secretly spent $1.5 million to fund an entire network of academic researchers whose goal was to shift the national health conversation away from the harms of sugary beverages. Instead, their research focused on the benefits of exercise—i.e., the health risks of sedentary and inactive lifestyles.

The research network disbanded after The New York Times published an investigation on the network’s funding in 2015. Coca-Cola’s chief scientist and health officer also resigned . But, that all went down just two years ago. It takes years to conduct, analyze, and publish research once grant money is in place. The funding for the new study may have come through when Coca-Cola’s research meddling was less clear. And, not to be too cynical, but it’s rather easy to imagine a soda executive saying: Americans are suffering with an obesity epidemic and health problems because we spend too much time sitting—never mind those 64oz sodas by their sides.

And that’s just the beginning of the study’s problems. Up next:

It didn’t actually measure sitting

Yep, a study basically claiming that sitting can be bad for your health didn’t actually measure sitting.

Oddly, the authors are a wee bit boastful in their manuscript that their study didn’t rely on participants' survey responses on how much time they spend sitting. This is a reasonable goal. People are notoriously bad at reporting what they do. Sometimes they may fib out of embarrassment. But more often people just don’t remember things well or have a perfectly accurate take on their activities.

So, instead of asking participants how much they sit, the researchers tried to measure it. Except they didn’t really. They used a hip-mounted accelerometer. In their words:

Our study has several limitations. First, the Actical accelerometer cannot distinguish between postures (such as sitting vs. standing); thus, we relied on an intensity-only definition of sedentary behavior.

The “intensity-only” definition of sedentary behavior is based on metabolic equivalents (METS), basically units defined by how much oxygen a person uses up doing various activities. But those definitions are also not cut and dried. There are no clear lines between lying down, sitting, standing in place, or light movement. All of those lie somewhere below 3.0 METS.

In the end, the data can add to evidence that a lot of time doing such low-intensity behaviors is bad—but we pretty much already knew that. This limitation really puts a damper on the author’s goals of coming up with a more nuanced look at behavior patterns and health risks.

Then there’s the participant data: It’s not representative—like, at all

The study drew from a pre-existing cohort of research participants enrolled in a study called REGARDS (Reasons for Geographic and Racial Differences in Stroke). The REGARDS study involved “30,239 white and black adults aged 45 years or older enrolled between 2003 and 2007 from across the contiguous United States.”

The sitting study borrowed 7,985 of those participants, who all agreed to wear the accelerometers. They were told to wear them for seven consecutive days for at least 10 hours each day. But some only made it to four days.

So, overall activity patterns were based on just a week's worth of data or less. And the ones who were more likely to go the full seven days were also the more sedentary ones.

The researchers used the accelerometer data to break the group of nearly 8,000 into four roughly equal groups, from the most active to the least active. At the time of wearing the accelerometer, the most active group’s mean age was 65. The mean age of the least active group: 75.

According to the study:

On average, participants with greater total sedentary time were older and were more likely to be black; to smoke; to not live in a stroke belt or buckle region; and to have diabetes, hypertension, dyslipidemia, estimated glomerular filtration rate less than 60 mL/min/1.73 m2, atrial fibrillation, history of coronary heart disease, and history of stroke. They were also less likely to be moderate or heavy drinkers, had greater BMI, and had lower levels of light-intensity physical activity and MVPA [moderate-to-vigorous physical activity].

The authors adjusted their modeling to try to account for these differences. And no matter what, this type of study can only pick out correlations, not causations. But, it’s worth noting that there were a lot of differing health factors between the groups.

Then there’s missing data and weak links

And we don’t even have the full picture of the health differences between the groups. The accelerometer data was taken about six years after some of the participants signed up for REGARDS and gave their initial health data. Some never gave follow-up health data. So if they had health problems or improvements in those six years—such as if they lost weight or developed diabetes—we don’t know. This could easily throw off risk calculations.

After the researchers collected the accelerometer data, they tried to keep track of the participants. Their median followup tracking lasted four years and ranged between six weeks and six years. During that tracking, 340 participants died.

The researchers then tried to look for associations between sedentary/activity patterns and mortality risks. They broke the 8,000 up again into four groups, this time by those who:

Sat little overall and tended to sit for short bouts

Sat little overall, but when they did sit it was for long bouts

Sat a lot overall, but in short bouts

Sat a lot overall and for long bouts

They next tried to look at mortality rates in each group at four years out. But, at the start, there were only 446 and 628 people in the two middle categories, respectively. During tracking, only nine and 30 people died within those two groups. Those categories are critical to parsing whether sitting bout duration, rather than just overall sitting time, contributes to health risks. Yet, they simply didn’t have the numbers to make any firm conclusions.

In the authors’ own words:

In analyses examining the joint effects of total sedentary time and prolonged, uninterrupted sedentary bouts, the sample size and number of deaths were small for the groups of participants who had high levels of only 1 of the sedentary characteristics (that is, high total sedentary time and low sedentary bout time or low total sedentary time and high sedentary bout time). Although the association between total sedentary time alone (but not sedentary bout duration alone) and mortality suggests that the volume of sedentary time may be the more hazardous sedentary characteristic, the small number of events and wide Cis [confidence intervals] in these groups render these findings inconclusive. Thus, caution is warranted when interpreting these results.

Annals of Internal Medicine, 2017. DOI: 10.7326/M17-0212 (About DOIs).