Short Bouts of Physical Activity May Offset Occupational Sitting CVD Risks

Having a job that involves prolonged sitting increases the risk for CVD, but even short periods of physical activity throughout the day may help mitigate the negative effects.

Compared with people who reported not mostly sitting while at work, those who were mostly sedentary had a 16% greater risk of all-cause death and a 34% higher risk of CVD mortality, a study of nearly half a million adults shows.

But the researchers, led by Wayne Gao, PhD (Taipei Medical University, Taipei City, Taiwan), say people in their study who alternated between sitting and not sitting at work saw a 16% reduction in all-cause mortality compared with those mostly sitting on the job.

“Furthermore, we found that individuals who mostly sit at work but engage in high leisure time physical activity have all-cause mortality comparable to that of individuals who mostly do not sit at work but had lower leisure time physical activity,” they write. High leisure time physical activity included jogging and running.

Commenting for TCTMD, Carl “Chip” Lavie, MD (Ochsner Heart and Vascular Institute, New Orleans, LA), said that correlates with most other studies in the field, which suggest that high levels of physical activity, exercise, or leisure time activity combined with less sitting can negate or almost negate the effects of prolonged sitting.

“It would be ideal to avoid the prolonged sitting, or at least do so less than 6 to 8 hours per day, but many are sitting [for] 10, 12, 14 hours per day,” he said.

In 2019, Lavie’s group published a large review on the health consequences of sedentary behavior and inactivity. A year later, the World Health Organization issued guidance on this topic for the first time. The US Department of Health and Human Services also has guidelines that recommend ways for people of all ages to accumulate bouts of moderate- and vigorous-intensity physical activity.

To TCTMD, Lavie said it’s clear that those at greatest risk from the detrimental effects of prolonged sitting are individuals with sedentary jobs combined with low overall exercise or leisure time physical activity.

The good news is that in the study by Gao and colleagues, bumping up physical activity seems to mitigate the risk.

Lavie added that standing desks are a good nonsitting option at work, as are frequent short walk breaks, even if only for 60 seconds. One way to ensure that happens, he added, is to increase water intake at work and force yourself to need frequent bathroom breaks that get you up and moving for those short periods of time.

Young, Educated, and Sitting

For the study, published January 19, 2024, in JAMA Network Open, Gao and colleagues examined data on 481,688 adults (mean age 39.3 years; 53.2% female) with no preexisting CVD who participated in a membership-based health checkup program in Taiwan between 1996 and 2017. The participants used questionnaires to self-report activity levels and sedentary time at work.

While about one-third of participants said they alternated between sitting and nonsitting at work, 60% reported mostly sitting. In the latter group, 47.5% described themselves as physically inactive, as did 52% in the alternating sitting and nonsitting group, and 57% in the mostly nonsitting group.

Compared with the other groups, adults in the mostly sitting group tended to be younger, with higher degrees of education, and were less likely to smoke, drink alcohol, be overweight or obese, or have hypertension.

People who were mostly sedentary on the job, compare with nonsitters, had higher all-cause mortality regardless of sex, age, smoking status, or chronic disease condition, with a similar pattern seen for CVD mortality.

Individuals who reported alternating sitting and nonsitting at work had no increased risk of all-cause mortality compared with mostly nonsitting individuals (HR 1.01; 95%CI, 0.97-1.05).

Furthermore, when participants were categorized by leisure time physical activity levels, those who mostly sat at work had higher all-cause mortality risk across all levels than those alternating sitting and nonsitting.

For those mostly sitting at work who reported either 15 to 29 minutes per day of leisure time physical activity or less than 15 minutes per day, increasing physical activity by 15 and 30 minutes per day, respectively, reduced mortality risk to a level similar to that of inactive individuals who mostly do not sit at work.

‘Denormalizing’ Sitting All Day

Gao and colleagues say prior studies on sedentary behavior and health risk suggest that hours of sitting contribute to lack of exercise of the large muscles in the lower limbs and trunk with increased blood flow to lower extremities that can contribute to reduced insulin activity, diabetes, obesity, metabolic syndrome, and poor kidney function.

“As part of modern lifestyles, prolonged occupational sitting is considered normal and has not received due attention, even though its deleterious effect on health outcomes has been demonstrated,” they write. “Emphasizing the associated harms and suggesting workplace system changes may help society to denormalize this common behavior, similar to the process of denormalizing smoking.”

Gao and colleagues further suggest that employers need to get involved in helping their employees get more activity during the day. In addition to standing desks and breaks, they suggest designated areas for leisure time physical activity or company-sponsored group activities.

To TCTMD, Lavie said other simple things like setting alarms on your watch or phone to remind you to take a standing and/or walking break for 60 seconds every half hour or hour should be encouraged.