Hello. These sentences are from children's storybook.
I am wondering what the underlined part means. Please help!!!
They all joined hands and danced round and round and kicked up their heels for joy, because they always did that whenever there was the least excuse for it - and quite often when there wasn't any at all, just because it was such good exercise and worked off their high spirits so that they could settle down for a while.
Let off or get rid of hyper energy so that afterwards they would feel the need to rest or have a break.