Advice for all long-haul air travellers

Be comfortable in your seat.

Drink plenty of water.

Be sensible about alcohol, as excess leads to dehydration and immobility.

Bend and straighten the legs, feet and toes every half-hour while seated.

Press the balls of feet down hard on the floor or foot-rest to increase the blood flow in the legs and reduce clotting in the vessels.

Use upper body and breathing exercises to further improve circulation.

Take occasional short walks (when in-flight advice suggests this is safe).

At stopovers, where possible, get off the plane and walk about.

Avoid taking sleeping pills, which will increase immobility.