A new type of athletic footwear known as a "sports sandal" has become one of the biggest selling outdoor products in recent years.

The sandal is a souped-up version of the traditional thong or flip-flop, which has a tendency to twist or slip off the foot. But these have thick rubber or foam soles that are held to the feet by wide, sturdy straps; some also have contoured bottoms to give them better grip.

Originally designed for use in rafts or kayaks, sports sandals are now promoted by some manufacturers as suitable for a variety of sports, including climbing, jumping and running. But some podiatrists and sporting goods experts warn that the sandals, while excellent for walking or aquatic activities, might not be for every sport.

Dr. Steven Subotnick, a podiatrist in Hayward, Calif., said that he had not seen any patients who were injured while wearing the sandals, but that that might be because people were not taking manufacturers' advertising claims at face value. Instead of Sneakers