麻豆传媒

Time spent standing, rather than sitting, was associated with lower fasting plasma glucose, triglycerides, and cholesterol in a new study.

Researchers attached a monitor to nearly 700 participants over 7 days and found that each additional 2 hours per day spent sitting was significantly associated with higher body mass index (risk ratio 1.03, 95% CI 1.01-1.05; P<0.001), waist circumference (Beta=2.12, 95% CI 0.83-3.41, or around 2 centimeters; P<0.001), fasting plasma glucose (about 1%), total/high-density lipoprotein (HDL) cholesterol ratio (5%), triglycerides (12%), 2-hour plasma glucose (4%), and with lower HDL cholesterol (0.07 mmol/L).

The study was led by , at the University of Queensland, in Australia, and appeared on Thursday in the .

The associations of sitting with fasting glucose and lipids were independent of moderate to vigorous physical activity, according to the researchers. Associations with the adiposity markers and 2-hour plasma glucose were no longer statistically significant after they were adjusted for exercise.

"These findings provide important preliminary evidence on the potential benefits of standing for cardio-metabolic risk biomarkers, especially improved lipid metabolism," wrote Healy and colleagues. "This has important public health implications given that standing is a common behavior, the most common alternative to sitting, and predominantly replaces sitting in some types of effective and acceptable environmental sitting-reduction interventions."

A lot of research has been done on sitting: a recent meta-analysis found that those who spent a lot of time in chairs faced a higher all-cause mortality risk, independent of whether or not they exercised after sitting. But exercise has been shown to lead to clear benefits for kids and adults who lead otherwise highly sedentary lifestyles.

Many have replaced sitting with standing, but the benefits or harms of standing aren't known and little research has been done on it, according to Healy and colleagues.

In the study, they also found that replacing two hours a day of sitting time with stepping was associated with a lower BMI (11%) and with lower triglycerides (14%) and higher HDL-cholesterol (0.10 mmol/L). In , , of Mayo Clinic wrote that the study offered an important contribution to the wealth of evidence pointing to the need to avoid sedentary behavior.

"The fight against sedentary behavior cannot be won based only on the promotion of regular exercise," he wrote. "A person walking while at work for 2 hours, standing for another 4 hours, and performing some daily chores at home for another hour will burn more calories than jogging or running for 60 minutes."

He added that those in the healthcare world, including policy makers, should look at ways to get people to move more often. "Healthcare providers, policy makers, and people in general need to stand up for this. Literally," he wrote.

Data were taken from the Australian Diabetes, Obesity, and Lifestyle Study, which began in 2000 but underwent its third data collection in 2011 and 2012. The authors wrote that 782 participants agreed to wear the activity monitor provided and, of those, 741 (73%) gave at least one day of complete data. The patients were an average age of 57, and 57% of them were women.

On the day that the participants were recruited, they underwent biochemical, anthropometric, and behavioral tests. And following an overnight fast, a standard oral glucose tolerance test was administered.

The activity monitor was from PAL Technologies and secured to the right anterior thigh with a hypoallergenic patch and waterproofed. All of the participants were told to wear the monitor continuously for 7 days and to record in a diary the times they went to sleep and woke up. Periods when the participant was asleep were not monitored.

Metabolic-equivalent minutes of stepping and time spent sitting, standing, stepping, and stepping as part of a more vigorous physical activity were totaled for each day; they were then averaged across the days, and intensity of stepping time was calculated.

Healy said that more work is needed to understand cause and effect.

"While the study cannot show that less time spent sitting causes the improvements in these markers of health, the associations it reveals are consistent with what is known already about the benefits of a non-sedentary lifestyle," she said.

In the study, blood samples were collected from the participants. Triglycerides, total cholesterol, high-density lipoprotein (HDL) cholesterol, and fasting and 2-hour post-load plasma glucose were measured. Blood pressure was taken using a monitor, and BMI was recorded.

The authors also collected information about patients' socio-demographic and behavioral attributes and medical history. Most of the patients provided at least 4 days of monitor data (97%), and 82% of them provided data for all 7 days of the study.

Limitations of the study included selection bias -- there were minor but statistically significant differences between the included participants and those in the larger study who opted not to do the tests.

"There was a tendency to exclude those with lower dietary fat intakes and those who were older, shorter, of lower socioeconomic position, post-menopausal, not taking the oral contraceptive pill, and with some poorer health characteristics," the authors wrote. "As previously observed there were some biases in loss to follow-up with a number of small but statistically significant differences in baseline characteristics between those who attended the wave three follow-up versus those who did not."

In addition, the authors noted that larger, and longer, studies are needed to establish definitive evidence.

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