It depends on whether you're playing a sport indoors or outdoors. You are encouraged to, but aren't required to wear a mask if:
If you're participating in an activity that requires people to be crowded together for longer periods of time, then you should wear a mask or not do the activity.
If you're playing a sport indoors where you're usually six feet apart and you come in close contact only momentarily, such as swimming, then the governor's order doesn't require you to wear a mask.
People sitting on the sidelines not participating in the sport at that time, or spectators in the area, should stay six feet away from other people or wear a mask, unless they’re exempt under Kansas Governor Executive Order #20-52.