Sorry, it’s a dreadful pun, but I couldn’t resist.
The stirrup is arguably one of the most important inventions in the history of mounted warfare, and of riding in general. The advent of the stirrup allowed a rider to mount more easily (making it feasible to wear heavier armour into battle), to rise out of the saddle and isolate his movement from that of the horse when necessary, and to recover his seat quickly when fighting in close contact with blows and grapples that may otherwise have ended in loss of balance or falls.
That said, an aid can easily become a crutch. Almost every riding instructor will agree that the best way to develop a good seat is by riding without stirrups, and almost every rider will benefit from dropping them from time to time. Only without stirrups can you train your legs and seat to respond naturally and intelligently to your horse’s movement. Training without stirrups is also insurance against the time (and it happens to all of us) that you lose a stirrup mid-gallop.
This is why one of the things we test in Riding level 1 is your ability to regain your stirrups.
13. Drop and retake stirrups at the walk
We’re looking for the ability to stay balanced in your tack without stirrups, and to retake them calmly by feel, reinserting your foot at the correct angle. This means your little toe will be against the outside branch of your stirrup iron, and your weight will be on the ball of your foot, with the heel lower than the toe.
Drop and retake your stirrups periodically as you ride. Not only is it a chance to loosen up the joints with some ankle rotations, it will improve your seat and your ability to regain your stirrups when you need to. If Xenophon rode without stirrups, you can too!