On Sept. 17, 2006, in the Netherlands, Lornah Kiplagat of Kenya set a world record in the 10-mile run after some unconventional training. For the two weeks before the event, while trying to rehab an injury, she ran almost entirely in a swimming pool. Easy on the joints, water running and water aerobics offer muscular and cardio benefits similar to their land-based counterparts -- but without the impact. As aqua exercise grows among pro athletes and the general public alike, a wave of water-specific shoes has arisen to meet the need. They protect the feet from abrasive pool floors, dry quickly and in some cases add resistance that pushes the workout to a new level.
AQx Aquatic Training Shoe
Innovative water shoe with a breakthrough technology: built-in resistance scoops.
Likes: Provides a significantly tougher workout and greater calorie burn than the other tested shoes; particularly works the hamstrings and glutes. The "gills" -- six 1- to 1½-inch plastic scoops (three on each side of the shoe) -- catch water and provide noticeable resistance (20 percent to 30percent more than regular shoes, according to AQx) as your foot lifts up after push-off.
Effective way to strengthen the leg-lift portion of your stride; works when running in place, so OK for small pools or deep hot tubs. Dislikes: Doesn't dry quickly, because of all-neoprene lining.
Price: $79.95. (800) 203-1276; http://www.aqxsports.com
SPEEDO Hydro XP
All-around water aerobics and running shoe.
Likes: Has a more flexible, comfortable, sock-like feel than every shoe here except the AQx. Quick-cinch lacing system. Partial-mesh upper allows the shoe to drain and dry quickly.
Dislikes: No resistance mechanism.
Price: $49.99. (888) 4-SPEEDO; http://www.speedousa.com .
MERRELL WaterPro Current
All-around water shoe with all-mesh upper.
Likes: Good for water running. Has a flexible ground feel; mesh dries very fast. Tough and multifaceted; actually designed for nonchlorinated water sports such as rafting or kayaking.
Dislikes: Comfy, but not sock-like, as are AQx and Speedo. No resistance technology.
Price: $75. (800) 789-8586;
Sprint Aquatics Aqua Shoes
Water aerobics shoes.
Likes: Ultra-lightweight. Fine for all water activities. The price.
Dislikes: Regular laces can come undone in the water (a new model with a Velcro closure is coming in September). The thick, stiffer white-foam sole is less tactile than the others.
Price: $40.45. (800) 235-2156; http://www.sprintaquatics.com
Roy M. Wallack writes for the Los Angeles Times.