SPENDING too much time sitting down is bad for your heart and waistline, a new study of postal workers has concluded.
The research found a link between sedentary work and a bigger waist circumference and higher risk of cardiovascular disease.
To avoid the risk, people may have to walk at least seven miles a day or spend seven hours per day upright.
The researchers studied 111 healthy Glaswegian postal workers who were kitted out with activity monitors for seven days. Fifty-five of them were office workers and 56 delivered post for a living.
The study revealed those who had desk jobs registered a bigger waist circumference – 97cm compared to 94cm – and approximately one BMI unit difference.
They also had a higher risk of cardiovascular disease – 2.2% compared to 1.6% over 10 years.
The research suggests waist circumference increases by two centimetres, and risk of cardiovascular diseases by 0.2%, for every additional hour of sitting on top of five hours.
Dr William Tigbe of Warwick Medical School at the University of Warwick, who led the research, said: “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.
“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.
“Our findings could be used as the basis of new public health targets for sitting, lying, standing and stepping to avoid metabolic risks.
“However the levels suggested in our research would be very challenging to achieve unless incorporated into people’s occupations.”
Participants in the study wore a tiny physical activity and position monitor called activPAL, invented by co-authors from Glasgow Caledonian University, strapped to their thigh for seven days.
They also had their weight, height and blood pressure measured, and provided blood samples.
Cardiovascular risks were assessed using the Procam risk calculator which takes into account age, sex, family history, blood pressure and metabolic measures.
The study took place between September 2006 and September 2007, involving volunteers from the Royal Mail in Glasgow.
Only apparently healthy non-smokers, with no personal history of heart attack, stroke, coronary heart disease, hypertension or diabetes were included.
Fellow researcher Professor Mike Lean of the University of Glasgow’s School of Medicine said: “Our evolution to become the human species did not equip us well to spending all day sitting down. We probably adapted to be healthiest spending seven to eight hours every day on our feet, as hunters or gatherers.
“Our new research supports that idea. The ‘bottom’ line is that if you want to be sure of having no risks of heart disease, you must keep off your bottom.”
The study, Time spent in sedentary posture is associated with waist circumference and cardiovascular risk, has recently been published in the International Journal of Obesity.