Nevertheless, this is actually an "everything" exercise - some people seem to be big fans of it as part of an ab-focussed work out; for me I need to motivate every muscle from the neck down to hold me in this awkward position for longer than 2 seconds. And for the whole time I am trying my hardest to not let my booty shoot up in the air, seriously focussing on hovering there and keeping my butt in line with the rest of my body is a feat of nature.
I did a series of planks mixed in with other exercises after some cardio, each time holding a plank for 45seconds or so. It was hard. And my muscles were shakey afterwards. And my brain hurt from all the concentrating too.
I hope you're all well out there. In the words of Jillian (whom I haven't mentioned for a record number of posts, but adore ever more), Peace!