Simplify the following text for a Grade 11 native English-speaking person.
Original: Ground fighting ( in martial arts sometimes referred to as `` ground work '' or `` ground game '' ) is hand-to-hand combat which takes place while the fighters are on the ground , generally involving a degree of clutching of gripping .
Simplified: Ground fighting ( also ground work or ground game ) is hand-to-hand combat which takes place while the combatants are on the ground , generally involving grappling .