“It's called the spiraling circle because you basically ride a growing and shrinking spiral on a circle.”

– Filippa Norrman

This is how you do it:

“The starting point for this exercise is a regular 20-meter circle, which you gradually decrease to an 8-10-meter circle before transitioning back to a 20-meter circle. As you decrease the size of the circle, you have to bend your horse more; otherwise, it won't be able to properly follow the smaller circle's path. This exercise enhances your horse's suppleness and collection as their inner hind leg must step further under when riding smaller circles.

This exercise can be done in all gaits but my advice is to start at walk in order to have enough control over the exercise and your horse. Then, you can transition to a trot and try to maintain the same level of control before moving on to canter. Once you feel comfortable with the flexion and bend, you can even mix it up with gait transitions.

To increase collection even further, the canter volt can be reduced to a working pirouette, where you have precise control over every stride.  Here, it's crucial to be mindful of your and your horse's limitations. The most important thing is that the horse remains relaxed throughout the exercise. If you set too high demands, tension can easily develop. 

It is also vital not to overdo the exercise or spend too much time on the small circles, as it can be quite demanding for the horse. Therefore, avoid riding this exercise for extended periods. Alternate it with riding some straight lines around the arena while aiming to maintain the same sense of control. And, finally, don't forget to include walking breaks.”