Are there any muscles protecting the kidneys from sports injuries?

Some. The kidneys are partly protected by the ribs (rib cage) and partly by overlying fat and muscles. Of course, the best protection is to avoid direct blows or forces and to use safety gear appropriate to the sport.
Refer to answer. Kidneys are in the back of abdomen, in retro peritoneal are. Are protected by strong para vertebral muscle, but however are prone to direct trauma and injury.
A few. There are some muscles that cover the areas of the kidneys. They are mainly protected by your rib cage. But there are muscles within the rib cage and overlying the rib cage, which give some additional protection to the kidneys.