Use Paste Posture to create multiple kicks:
You can use the Copy Posture tools to quickly duplicate all the leg keys from
one frame to another to create repeated kicking motions.
1 Make sure that Auto Key is still on and move the time slider to
frame 0.
2 On the Track Selection rollout, click Symmetrical.
Now both legs are selected.
3 Click Copy Posture at frame 0. Name the copied posture R up L
down.
Creating a Simple Freeform Animation | 773