Editor's note: This popular story from the Daily Briefing's archives was republished on June 18th, 2019.
Prolonged inactivity could increase an individual's risk of an early death, regardless of their exercise habits, according to a study published Tuesday in the Annals of Internal Medicine.
For the study, researchers examined the association between sedentary behavior, both sitting and standing, and all-cause mortality by using accelerometers to track the movements of 7,985 black and white adults ages 45 years or older. The researchers tracked sedentary behavior by total volume, prolonged accrual, and uninterrupted bouts. The researchers followed up with study participants for four years.
According to Reuters, the observational study is unlike previous research on sedentary behavior, which has relied on self-reported data from study participants who recalled and reported how much time they spent in motion. However, the researchers noted that the study was not a controlled experiment designed to determine causation.
The researchers found that, on average over a period of 10 days, sedentary behavior accounted for 77 percent—or 12.3 hours—of a 16-hour waking day. According to the study, bouts of sedentary time on average lasted for about 11 minutes, though they ranged from under 30 minutes to more than 90 minutes per seated session. For instance, Reuters reports that the researchers found:
- 52 percent of study participants' had stretches of sedentary time that lasted less than a half-hour;
- 22 percent lasted between a half-hour and just under one hour;
- 14 percent lasted between 60 to 89 minutes; and
- 14 percent lasted 90 minutes or more.
When compared with the least sedentary individuals in the study—those who spent about 11 hours total per day sitting and standing—the most sedentary study participants—those who spent more than 13 hours total per day sitting or standing—were twice as likely to die of all causes over a four-year period.
The researchers also looked at the correlation between sedentary bout length and mortality and found participants whose sedentary bouts were longer were more likely to die than those with shorter sedentary bouts.
Lead study author Keith Diaz of the Center for Behavioral Cardiovascular Health at Columbia University Medical Center said participants who spent more than 12.5 hours per day inactive for durations longer than 10 minutes had the highest risk for all-cause mortality, regardless of whether or not they exercised.
Diaz said the "findings suggest that it is simply not enough to be active or move at just one specific time of the day, that is, exercise." He continued, "The simple, straightforward implication is that excessive sedentary time may be a toxic, hazardous behavior and that regardless of whether a person exercises on a given day, they still need to be mindful of how much time they spend sedentary outside their exercise time."
David Alter—the head of cardiovascular and metabolic research at the University Health Network-Toronto Rehabilitation Institute, in an editorial accompanying the study—cautioned that "observational studies, no matter how well designed, cannot imply causality." Still he noted it is possible that prolonged inactivity could result in an early death due to metabolic toxicity. "The lack of activity in our muscles affects our ability to metabolize our sugars efficiently," he said, adding, "Over time, our body accumulates excess fat, which can lead to obesity, diabetes, heart disease, cancer and death."
James Levine, an obesity expert at the Mayo Clinic, said it is not surprising that the researchers found exercise cannot undue the effects prolonged inactivity can have on the body, because studies have found that even short-term changes in activity over time can have profound effects on individuals' risks of diseases tied to sedentary behavior. He said, "Even if you're a gymgoer and think you're safe on account of your excellent effort, you are not," adding, "If you're sitting too much, you need to do something about it—like right now."
According to the Los Angeles Times' "Science Now," the researchers recommended individuals get up and move at least every 30 minutes to counter the health risks of sedentary behavior (Rapaport, Reuters, 9/11; Healy, "Science Now," Los Angeles Times, 9/11; Bachert, MedPage Today, 9/11).
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In this briefing, we profiled six leading institutions have successfully integrated outpatient diabetes services into their primary care networks. Read it now to learn how an effectively implemented program can benefit PCPs who may otherwise be unable to provide quality diabetes care to their patients and help your organization set itself apart from the competition.