Vertical/horizontal zigzag transformation of a circle in illustrator

I would like to transform a circle in a zigzag shape in only one direction, either horizontal or vertical - not both. The zigzag effect does it in all directions. Can I change it somehow? Or is there another option. Like this:

Answer

Make a Zig-Zag effect on a path with an odd number of waves

Menu Effect > Warp > Apply a Warp Arch

Copy > Past in Front

From the Appearance Panel edit the Warp and change the bend for a negative number

Result