Hi Bronya, there are some real endurance folks around here, can't think why they haven't answered, maybe they are busy!
Last year, all winter, spring, and summer, I rode an average of 1-3 hours a day, trails only, 5-7 days a week. My horse made fast work of a 12 mile novice CTR in July. I can't imagaine with all that riding that you do, your horse wouldn't eat up a 25-mile ride. The horse will probably get pretty excited at the event--new place, new horses, etc., and he'll blow right through it.
I read in a couple of places that you get a horse ready for 25 miles by riding only 3 days a week for 8 weeks if you did it right.
More riding than your horse needs. I would suggest 3-4 times per week.
P.S. I've had two horses with stifle issues. Jumping and cantering isn't what I'd recommend. Maybe I should say, if your horse has had any pain or injury associated with the loose ligaments that are associated with locking stifles. Anything that causes the hind leg to extend further backward is counter productive. So extended trot, canter and jump work all cause the leg to push further back which can cause the ligaments to over extend and become sore and loose again. Uphill work at a slower trot or marching walk, will do wonders. But if your horse hasn't had any soreness or injury causing the loose stifles and is stalled regularly then I can see the reason for daily exercise. There's nothing worse for stifles then standing around in a stall.
She's sugar intolerant to the point where she's virtually allergic to grass so has a little grass-free paddock during the day unless it's raining when she has to come in or it ends up knee deep in mud. As a result, she gets little to no exercise other than when she is ridden. If I'm lucky I can grab some turnout in the school but not always so she has to be ridden on the other days, or she goes nuts (and her legs get really bad). Picture a horse that's so wound up it's dangerous to ride, bucking, mini rears, the lot, so full of adrenalin at being out that nothing stops it, and that's her if she's kept in without exercise. With exercise, she's terribly sweet and relaxed.
We have tried so many things to help her legs. 24/7 turnout was the best, though that's now out of the question. Jumping, particularly bounces, builds up the muscle quite fast in her quarters and when we do it regularly really helps. We don't jump high though - about 2ft max, certainly no higher than her more enthusiastic leaps and bucks when in her paddock. Lateral work and circles help too. Her legs are congenital - cause no pain and were not caused by injury. In the summer they improve hugely and then she probably could have the 'walk' days off when she's able to go out.
Is it possible for you to build a larger paddock or a racetrack? This way, it will allow your horse to exercise whenever he wants to.
My Arab is also very sensitive to sugar in grass so I'm going to make a racetrack on our property - it will be about ten feet wide going around my farm so Abby will have to walk alot to look for whatever grass she can find. If it does not work, then I will put her in a large dry lot during the day and let her out in the race track during the night.
One of our horses' hocks were very stiff when he first came here but is now able to move more freely out in our large pasture...so moving around all the time like they're supposed to is works wonder on his body.
Will get a dream horse!
More riding, swimming, and rowing, less posting
I wish! I board my horse and this is the only place I could find that would even let us have a little paddock! Anywhere else and she would have had to be stalled 24/7. I just need a pay rise - and some cheap land!
Your schedule looks like too much work. Just ride the horse, have fun, do anything that strickes your fancy and have fun just spending time on her back.
I believe it is about time spent on her back rather then the training schedule.
A 25 miler is usually limited to 4 hours minimum. It is easy to cover the distance in that time with almost any horse. Don't worry too much.
Get out, spend hours on the horse having fun.
If you only ride 1 hour every day it never gets the horse ready for 4 hours. Spend longer times and ride as often or whenever it pleases you.
I average 50 miles each week just having fun, don't worry about training, just go out and ride.
A good working trot is 8 mph so judge distance traveled by time at a trot.
I find a lope is only 9 mph and easier on me so I spend alot of time at a easy laid back lope.
Again I too was worried about my first 25 and found it far easier then I thought.
I see your situation. You really would not have to ride as hard as you are proposing to get a horse who is so game ready for the event physically.
Given her restrictions, I would consider as much walk and uphill slow work as possible, not a huge fan of lots of jumping and circles for distance training - wears out a horse's body too much. Horses are meant to walk and eat, with naps in-between. If she has limited turnout, I would try to walk her LOTS. Vary arena routines - maybe work on a slow jog or collection one day, jump another, etc. Galloping/fast canter 20m circles for an hour is not a good way to build muscles or wind, too much joint strain, IMO.