The worn-out, smelly old sneakers you're about to throw away might have life in them yet. Hong Kong-based Fieldturf Asia is at the forefront of turning unwanted shoes into hi-tech playing surfaces for sports like basketball, tennis, athletics and soccer. Five such pitches have been constructed in Hong Kong since 1998. The first pitch was laid at the University of Hong Kong in Sandy Bay in 1998, a second was installed at the King's Park rugby ground in Kowloon in 2003, while a further three pitches have recently been laid in Tai Po, West Kowloon and Tung Chung. James Middleton, managing director of Fieldturf, said Hong Kong's subtropical climate was far from ideal for grass pitches. 'Grass pitches need time to recover from the wear of competition, so only a limited playing schedule is suitable in our climate,' said Middleton. 'Manchester United's grass pitch at Old Trafford can be kept in good condition as it's played on only about once every two weeks. Recreational pitches in Hong Kong see much more activity than that, so it's very difficult to keep them maintained and in good condition.' A 10-year cost analysis has shown that grass is 10 times more expensive to maintain than the new artificial surface. At 10,000 square metres, the Tai Po pitch is the largest of its kind in Asia, while the Tung Chung and West Kowloon pitches have been designed primarily for seven-a-side play, and each measures 3,240 square metres. By using an artificial surface, the Leisure and Cultural Services Department can now lease out the pitches with a much-improved playing schedule and hence bring in greater revenue to offset maintenance costs. There is very little difference in the overall construction cost of both grass and artificial pitches. According to Middleton, the cost to build a full-sized sports pitch is between $4.5 million to $5 million. The discarded shoes are simply sliced into three primary portions - the rubber outsole, the midsole foam, and the upper fabric or fluff. The materials are then ground down into small particles and cleaned. The resulting material is called Nike Grind. The upper fabric is used as padding under hardwood indoor basketball floors, and to cushion the impact of the players' often hard landings. The midsoles are re-cycled for use on synthetic basketball courts, tennis courts and playground surfaces while the rubber from the outsole goes into running tracks and football pitches. It takes just 3,000 shoes to make a basketball court or 100,000 shoes to create a new running track. Fieldturf has installed artificial pitches at more than 1,500 locations worldwide, including famous sporting landmarks such as the Tokyo Dome. The surface has also been approved for major international events by organisations such as Fifa and Uefa. In the UK, 75 per cent of Premier League football teams practice on synthetic pitches laid by Fieldturf. Dongdan Field, in the heart of Beijing, is the busiest football pitch in the world with an average of 700 players per day, and is also covered with Fieldturf's artificial surface. All this is a sad reminder that the Hong Kong Government Stadium in So Kon Po is still covered in pasty-looking grass and is seldom used for major sporting events. 'If you calculate the labour, machinery, chemical and maintenance costs at So Kon Po, and work it out on a dollar per hour basis per square metre, you would be shocked with the result,' added Middleton. While the purists may well see the hallowed turf of Wimbledon as the supreme tennis surface, the day might not be too far away when the shoes that are treading the turf today are ground up to make way for the playing surface of the future. BOUNCING THE BACK THE SYNTHETIC GRASS The hybrid fibres are a polyethylene and polypropylene blend that are woven into a porous mat. Each blade is UV-coated and placed to look like real grass. The blades can withstand extreme temperatures and are more durable than natural grass. THE INFILL The graded silica sand and finely ground rubber mimics natural earth, holding up the synthetic blades. The loose infill is spread between the blades in layers, and can be kicked up as an athlete runs over it. HOW IT DRAINS The porous design of the turf can take up to 40 inches of rain without losing playability. Water drains through the hybrid blades and its backing and down the mesh mat. Water then runs along asphalt to concrete drains set around the mound of the football playing area and around the entire field.