Why do they use the word BREAK for everything a horse does?

Question

Break his/her maiden
Break at the post
Break down, I hate this one
Break a horse
Break, a high horse-drawn carriage with four wheels

I watch TVG and HRTV, they use the word break 10 times an hour at least.

Answer 1

these are some word they use
-trot
-post
-mount
-dismount
-canter
-gallop
-walk
-woh
-heya

Answer 2

I think now-a-days it is just a figure of speech. However, back in the day, a horse was "broke" to ride when it no longer acted on its own free will. So therefore the spirit was broken. I think you may be putting too much meaning into this.