What on earth is planking?
I hate to be pedantic (that's a lie; I love to be pedantic), but "planking" is not the same as the plank exercise/pose. This is planking: [link] as explained by Wikipedia: [link]
The plank pose is a pilates pose (I think; or maybe yoga) that is great for your abs and harder than it looks: [link]
This post brought to you by someone who giggles every time someone mentions a "planking" challenge, because the mental image is hilarious.