If you ran on the beach for an hour, would you run in the deep soft sand or the wetter sand closer to the water? Most of us would choose the wetter sand that provides a stable surface while still offering some ‘give’.
Running in soft deep sand doesn’t give a stable landing, and the sand particles move as we land on them, making the surface even less stable. It’s likely to hurt your knees, ankles and hips if you keep going in that footing.
The joints in the horse’s legs are not designed for ongoing work in deep loose footing any more than ours area. When the horse lands in deep loose sand, one side of a foot will land first, sending a concussive force up the limb into the bone and cartilage. The other side will land ‘late’, and this creates a jerking effect on the ligaments and tendons. Over time, this will predispose the horse to ringbone, an arthritic condition that can have dire outcomes.
Even a short ride in deep sand footing can cause back strain in your horse, in the same way that your back muscles are likely to ache if you run in deep sand for more than a few minutes.
Soft pasture is ideal footing, and for most horses kept for recreational purposes, it’s where they live. If you ride in an arena regularly, look carefully at the depth of the footing. If the surface is dry sand more than a couple of inches deep, look to make changes.