In the Motion track of the Timeline, import a prepared motion/animation clip by selecting Import in the right-click menu (right click on the track) or by clicking the import button in the Modify panel.
Import the same motion clip right after it.
Play the project from the start frame. You see the actor pops back to the ground when the play head reaches the 2nd clip.
Right click on the 2nd clip and select Reverse in the menu or click the Reverse
button in the tool bar of the Timeline.
Play the project. You see the actor lays back to the ground in a reversing method of the original motion clip.