In FL we don`t have many hills, no mountains so it is difficult to condition and strengthen a horse without using speed which is risky. We do have sand everywhere and sand can be used as a partial substitute for hills. When a horse moves in sand two things happen that don`t happen on firm ground. First the heel of the hoof is narrower than the front and middle so the hill sinks - hence putting stress on the tendons. Secondly, as the horse pushes with its hind legs the sand absorbs much of the force and the horse compensates by pulling with its front legs. if you ever notice a horse that dose a lot of work in the sand it has big forarm muscles and shoulder muscles.
The two things you need be aware of when you start conditioning in sand are the above factors. Sand will place a lot of stress on the tendons so it should be done with care at first. When a horse is conditioned correctly using sand he will have tendons like steel cables. If you rush it you can eailly blow a tendon. Also most horses have relatively small forearm muscles and these need to be brought along slowly.
How you start depends on a lot of factors - the most important is the base the horse already has. If the horse has a good base of several years then the tendons should already be strong and starting with long stretches on easy trotting should be no problem. This can be worked up to intervals of trotting and cantering. I always watch the legs carefully for any sign of inflamation. When a horse moves in the sand his fetlock joints move in ways then don`t normally move. This can cause inflamation. One well known DVM told me one time that sandy conditions are harder on the joints than hard surfaces. She recommended the use of such things as Adaquan for horses that a lot of sand work. A lot of horses in FL develop windpuffs because of the sand.
If your horse has a long low stride then trotting int the sand might make his hocks sore since he will have to pick them up farther than he is used to. This is also somthing to watch out for. I have found is that it seems to be easier on the horse (after he is in shape to do it) to canter in the sand than to trot. Cantering gets him up and out of the sand naturally where horses with a long low trot have trouble getting up and out of the sand.
I train once a week in an area that is rolling sandy hills. Nothing very long or steep but very sandy in most places. There are some sand roads that are "firm". My training consists of trotting and galloping up the sandy hills and trotting on the flat. I also alternate between the sandy trails and the firmer roads. When I started training Misty here she had about 500 competitive miles under her girth. I introduced the deep sand slowly by doing more walking than normal, and trotting and cantering up the hills to build strength. After about two months (decreasing the walking time) I was basically trotting and cantering for about 12 miles, resting for a while and troting and cantering back home for about 12 to 15 miles. In about 3 months after I stared her sand training we did the Far Out Forest 100 (about 90 miles of deep sand) and she finished in great shape.
When I started Dan in the sand ( he is 8 and has about 100 miles) I did mostly walking. I would walk and trot for mile stretches for about 12 to 15 miles. After about three months I am adding uphill canters. I would think it will be about nine more months before he is caught up with Misty as far as workout.
Going down sandy hills is one of the most stressfull things you can do the the legs so I tend to walk the steeper downhills.
A lot of people fear the sand. The first question people ask about rides in FL is the amount of sand. Sand is nothing to fear but it sure is something to be respected. In the flatland sand may be the only thing that you have to strengthen your horse.
Hope this has helped
Truman Prevatt, Sarasota, FL