The cleats on outdoor soccer shoes feature projecting studs or blades of thermoplastic polyurethane. These are designed to give you the ability to execute long kicks and cuts on the natural grass of an outdoor field. Outdoor cleats can be bought for firm ground and for hard ground surfaces, such as rocky, dry or dusty fields. Outdoor cleats create problems for certain indoor soccer arenas, though, which feature artificial surfaces.
If you find yourself at an indoor game with only outdoor cleats in your gym bag, you may be out of luck unless you can borrow some correctly sized indoor shoes, which feature flat soles with treads made out of gum rubber. If the indoor arena features Astroturf, a green carpet-like material with a short pile laid over concrete, clattering around in cleats would tend to destroy the surface, the soles of your feet and your shins as well. Managers at indoor arenas with Astroturf ban outdoor cleats and tend to keep a sharp eye out for evidence that players might be bringing outdoor cleats onto the playing area.
If an indoor arena features FieldTurf, with plastic strands of artificial grass held in a bed of sand and shredded rubber, or AstroTurf’s similar AstroPlay product, more knowledgeable arenas will let you play with hard-ground cleats, with their shorter studs than firm-ground cleats. For arenas that still forbid cleats even on FieldTurf in their house rules, you may be able to obtain a one-time waiver from the manager until you can obtain indoor shoes. In fact, FieldTurf’s website states that “metal and aluminum rounded molded cleats are acceptable,” but not jagged metal cleats. The maximum recommended stud length is a half-inch. FieldTurf states that flat-soled shoes do not result in ultimate performance, indicating that polyurethane studs on soccer cleats do not pose a risk to the surface.
Among soccer arenas that permit indoor cleats, the Sportsplex in St. Charles, Illinois, notes that cleats must be “hard ground molded” for soccer. Soft ground cleats are forbidden as they have longer studs. The Saskatoon Soccer Centre requires that indoor shoes be clean and not have black soles that could mark the arena floors. Numerous indoor college soccer leagues forbid cleats altogether.
Your best solution is to buy indoor shoes or temporarily wear running shoes if you are playing on an Astroturf indoor soccer field. You can also wear what are called turf shoes, an outdoor shoe with short nubs designed for rocky, dry, hard fields or outdoor artificial surfaces. If you buy indoor shoes, look for a rubber or synthetic sole, recommends Ned McIntosh in “The Baffled Parents' Guide to Coaching Indoor Youth Soccer.” Examine the shoes for good heel support and sizing so that they are not too wide, to avoid blisters, but long enough to allow for possible swelling of the foot as it heats up, with enough room for the toes, he writes.