SOME 70 per cent of van drivers have taken time off work due to back pain - costing the UK economy on average £21 billion per year, according to a Volkswagen Commercial Vehicles survey.

Drivers who suffer from ‘Builder's Back' take an average of three weeks off work and the resulting downtime costs companies an estimated £500 a day per van.

Poor seat adjustment could be to blame for triggering back issues, especially as many drivers spend up to seven hours a day in their vans.

During a day's testing spent at the Cordwallis Van Centre at Heathrow near London, Volkswagen Commercial Vehicles and a chiropractor from the British Chiropractic Association discovered that two-thirds of drivers are sitting incorrectly in their vehicles or missing crucial steps.

Prab Chandhok, chiropractor and member of, British Chiropractic Association, said: "Many people now point to driving as a trigger for their back or neck pain, so it's really important that your van is set up properly for your needs, to help ease the strain that driving - especially for long periods of time - can have on your back and neck.

"The key thing to remember is that there is no single seat that is perfect for everyone, so it's practical to test the seat out fully before you buy a new vehicle. The more adjustable it is the better."

Volkswagen and the BCA have now come up with the following seven tips to help van drivers sit properly in their vehicles.

HEIGHT: Your thighs should be as parallel to the floor as your seat will allow, and where possible try to get your hips higher than your knees. You should also adjust the thigh support if you have one to ensure you have the maximum surface of your thighs touching the seat.

PEDALS: You should be able to push the pedals to the floor with a bend in your knees.

110 DEGREES: Bring your seat all the way up so it's straight and then take it back until you are comfortable whilst maintaining a 110 degree angle between your back and thighs.

LUMBAR SUPPORT: The lumbar support should be adjusted so you can feel it support the hollow in your back but so it's not causing your spine to arch more than is normal for you.

HEAD RESTRAINT: The height and angle of your head restraint should be adjusted so you can feel the centre of the support touch the middle of the back of your head, although it does not need to be touching at all times

STEERING WHEEL: Once in correct seating position, bring your arm up in front of you and position the centre of the steering wheel to be in line with the fold of your wrist.

REAR MIRROR: Lift up your chest by five degrees and then adjust your mirrors to help stay in an upright position on long drives.

Volkswagen says its Crafter van offers both ‘ergoComfort' and ‘ergoActive' seats, allowing van drivers to individually adjust their seats for an optimal driving position.

The ‘ergoComfort' suspension seat features optimal back care with up to 20-way adjustment. The suspension seat softens unpleasant bumps and jolts which can jar a driver's back.

The ‘ergoActive' system offers 14-way adjustment, including a massage function, with back-friendly ergonomics that ensure the hours spent behind the wheel are as pleasant as possible.