A New Mexico-based company which produces "pain relief" running shoes with a spring in the heel to people aged 50 and over has revealed it has almost tripled its sales in the past 12 months.

Z-Coil Shoes, of Albuquerque, said it is shipping around 5,000 pairs of shoes a month as older consumers with foot and leg pains rush to snap up the design that boasts a plastic brace like that seen in an orthopaedic shoe.

Company chiefs say sales have shot up 270 per cent in the past year and are expected to grow a further 250 per cent in the next 12 months as its 150-strong dealer network continues to expand.