3/3. Sports Fabrics. Not so long ago, athletes competed in cotton vests and baggy shorts. But in today's competitive climate, athletes look to hi-tech sports fabrics for sporting advantage. Sports clothes are now marketed to the public and science has become a major selling point. Jonathan Edwards discusses some of the new textiles with scientists and manufacturers. Breathable fabrics might allow sweat to escape and at the same time keep the rain out. but will they improve performance? Producer John Watkins