Proper saddle fit is critical for ensuring your senior horse's comfort and longevity, especially as they experience age-related changes such as reduced muscle tone and arthritis.
Ten percent of U.S. senior (15+ years) horses are used for competition according to their owners, and some appear to compete at the highest/international level.
There are many materials you can use for footing in an equine arena or round pen. Some of the materials are used in combination. Check out these tips on footing from Animal Arts.