An analysis of postal workers in Glasgow, Scotland, found that people who spent more time in a sedentary posture during work had a larger waist circumference and an increased risk of cardiovascular disease.
Lead researcher William Tigbe, PhD, of Warwick Medical School in Coventry, United Kingdom, and colleagues published their results online in the International Journal of Obesity on March 1.
The cross-sectional study took place between September 2006 and September 2007 and enrolled 111 workers from the Royal Mail in Glasgow, including 55 who worked in the office and 56 who delivered mail. The workers were healthy, did not smoke and did not have a history of MI, stroke, coronary heart disease, hypertension or diabetes. They also did not take lipid, blood pressure or glucose lowering medications.
Each of the workers wore a physical activity monitor for seven days. They strapped the monitor to their thighs, except for when they bathed or swam. The researchers measured participants’ weight, height and blood pressure and took blood samples.
The mean age of participants was 40 years old, while the mean body mass index was 26.9 kg/m2 and the mean waist circumference was 95.4 cm. In addition, the mean high-density lipoprotein (HDL) cholesterol level was 1.33 mmol/l, the mean low-density lipoprotein (LDL) cholesterol level was 3.11 mmol/l, the mean trigylcerides level was 1.23 mmol/l and the mean 10-year PROCAM risk was 1.8 percent.
On average, the participants spent 9.1 hours per day in a sedentary position, 7.6 hours per day sleeping, 3.9 hours per day standing and 3.3 hours per day stepping.
The mean waist circumference was 97 cm in desk job workers and 94 cm in those who delivered mail, while the 10-year risk of cardiovascular disease was 2.2 percent and 1.6 percent, respectively.
“Longer time spent in sedentary posture is significantly associated with larger waist circumference, higher triglycerides (fat in the blood) and lower HDL cholesterol, all adding up to worse risk of heart disease,” Tigbe said in a news release. “The levels associated with zero risk factors were walking more than 15,000 steps per day, which is equivalent to walking seven to eight miles, or spending seven hours per day upright.”
A univariate regression analysis found that waist circumference, fasting triglycerides, HDL cholesterol and PROCAM risk were detrimentally associated with sedentary time. The analysis adjusted for age, sex, family history of coronary heart disease, shift worked, job type and socioeconomic status.
The researchers found that for every additional hour of sitting on top of five hours leads to a 2 cm increase in waist circumference, a 0.2 percent increased risk of cardiovascular disease, an increase in LDL cholesterol and a decrease in HDL cholesterol.
“Our findings could be used as the basis of new public health targets for sitting, lying, standing and stepping to avoid metabolic risks,” Tigbe said in a news release. “However the levels suggested in our research would be very challenging to achieve unless incorporated into people's occupations.”
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Tim Casey joined TriMed Media Group in 2015 as Executive Editor. For the previous four years, he worked as an editor and writer for HMP Communications, primarily focused on covering managed care issues and reporting from medical and health care conferences. He was also a staff reporter at the Sacramento Bee for more than four years covering professional, college and high school sports. He earned his undergraduate degree in psychology from the University of Notre Dame and his MBA degree from Georgetown University.