I'm reminded of the format of Lucinda Green's cross country clinics which focuses on jumping little things on non-specific distances:
I found this article by William Micklem on the very subject through COTH today:
TEN WAYS TO GET INTO FIFTH-LEG TRAINING
A number of you have asked about specific ways to train your horse to develop a 'fifth leg'. Below I list 10 good ideas for improving your horse’s fith leg and reducing the risk for accidents. I also aim to make fifth leg training part of every riding session as there is nothing more important than rider safety and fifth-leg training is the best insurance policy on the market:
1 - SELF CARRIAGE IN ALL ACTIVITIES
Allow the horse to be in self-carriage. Do not try to support through the rein contact because this only restricts the use of the head and neck and encourages the horse to take more weight forward as they try to lean on the contact. The reins should always be a communication point not an attempt at a support point.
2 - TURN OUT TERRAIN
As far as possible, even just for their holidays, turn your horse out on hillsides and in fields with varied terrain so that he gets used to going up and down hills. This is especially important for a young horse. So you should try and buy a horse who has had this experience and avoid those who have only experienced a flat arena and minimal turn out. Watching horses gallop freely and nimbly over undulating fields should also encourage riders to trust their horses to look after themselves.
3 - RIDING TERRAIN – LEAVE THE STANDARD ARENA
When hacking, deliberately walk, trot, and canter up and down banks and over undulating ground and varied terrain. You may not live in the country or in an area suitable for hacking, but this is of such benefit to your horse that you should consider transporting him to somewhere with good hacking on a regular basis so that he learns to become more agile. In addition do your dressage training on this varied ground. It is very useful if part of your schooling area has a small incline so that you can practise maintaining controlled impulsion as you go up and down a slope. As well as the benefits for fifth-leg training, this has considerable advantages for the physical development of your horse. Riding out and about is so important for both the mind and the body of your horse.
4 - LOOSE SCHOOLING
With the help of a coach, practise loose schooling your horse – without a rider or tack – over fences. This will teach the horse to make decisions about how to respond to the exercises without relying on his rider to guide him.
5 - MINIMAL INTERFERENCE
During jumping training, make sure you interfere with the horse’s jump as little as possible. It is difficult to sit still and make only the smallest of changes as you ride but, if you can do this, it will greatly benefit your horse’s fifth-leg training as they are encouraged to take more responsibility for judging the take off point and the effort needed.
6 - 'WATCH' EXERCISES
Put logs or sleepers in front of every stable door, between fields, and along riding tracks. In this way your horse will have to continually practise looking after himself, watching where he puts his feet and developing his coordination. This is particularly important for young horses.
7 – BANKS
Build solid, wide banks around your yard, along the side of the drive and between paddocks suitable for jumping at a slow speed on a regular basis.
8 - VARYING JUMP DISTANCES
During a jumping training session, start with standard jumping distances and/or distances that suit your horse, but then both slightly shorten and slightly lengthen them. A standard showjumping stride length is 3.5m, but you can gradually train your horse until he copes with a 3m or a 4.5m stride length. To do this you will also have to decrese or increase the speed but try to have no increase or decrease of weight in the rein contact. This process may take many months to achieve and will need the help of your coach but the results will be worth it.
9 - 'HUNTING' OVER FENCES
Make all small, 50-75cm, schooling fences as solid as possible so that your horse treats them with respect and because this will be safer as there will be no falling poles to trip over. Then with the guidance of your coach jump them not only on straight lines but off turns and at all angles, gradually using varied terrain and varied distances between fences. this is all done with the minimum of interference, with the rider just choosing the right direction and speed. (Your coach can guide you about doing the same thing over slightly bigger fences, however do NOT school over big, solid fences at home for reasons of safety and maintaining the horse’s confidence). This is also excellent preparation for learning how to jump 'against the clock' in show jumping.
10 – WATER, WATER, WATER
This is especially valuable because horses need plenty of time to develop confidence and a 'fifth leg' for water jumps. Permanently fill a natural dip in or near the yard with water (including ways for excess and dirty water to drain away) and then ride through the water on a daily basis. This might be on the route to your riding arena.
I have to remember #1 with River because he is still very unbalanced. #10 is my next step with Pom Pom. She has crossed the creek on her own, now she has to do it with ME on her back (muah ha ha ha). A neighbor offered us their near by field for turn out. It's on the side of a hill like #2, but the fencing is horrible. Hub and I need to go walk the fence line. I've been thinking about building a bank and a ditch in the pasture like #7, maybe that will be a summer project (that and working on the "mud pit" aka the arena).
The following is from a post on COTH that I thought was really good:
I try to teach them to balance themselves when they are green. E.g. trotting or cantering a circle, I will go in 2-point and put my hands on the neck, and expect them to maintain the same speed & balance. Of course, in the early stages they can't do this. So I half-halt, then get off their mouth and try again. It has to be built up.
I take them out on trail rides and don't hold them up when we are going up and downhill or across uneven terrain. But I insist they maintain the pace I have chosen - with half-halts. I will pull them up and halt if they're not listening. If they stumble consistently, I kick them in the gut - it is their job to pick where their feet are going and to PAY ATTENTION to their feet - not mine. (Having said that, I am careful about good footing and try to avoid rocks and holes.)
On green/young horses, this takes a bit of gumption - because they will stumble, they will slip, they will start trotting on their forehand down the hill. But if I always hold them up and package them and save them and tell them where their feet should go - how on earth can I expect them to make smart decisions about where their feet should go in a light-to-dark drop jump, or a bounce combination on XC, or on slippery footing, or if they stumble before or after a jump?
When I start them jumping, I let them pick where they take off at trot and canter. I get the most balanced gait I can, and I give them soft reins for the last 3 or so strides. I sit up and expect ugly jumps, stumbles, crashes, pecks, long spots and short spots. I do tons of grids and give them loopy reins and stay out of their way. I make small corrections (like leg-yielding or a guide rail if they're off the line) and praise them when they improve. They have to make mistakes in order to learn.
I take them outside and jump fallen trees from weird lines and distances and get them to deal with avoiding the big rocks and gullies and branches etc. I let them land and decide what to do with their feet around all those things and pay attention to the trees that we are weaving around. If they make a stupid decision or take off or spook or swerve, I will make corrections like pulling them up or leg-yielding or even doing it again and giving them a chance (or me, if I got a bad line) to make a better decision.
This is all done at 18" - 2'6, starting with things the horse could walk over if it needs to, then gradually increasing until they are confident and making good decisions.
As they get more broke, I can help them more - but have to remind myself not to always do that. I always force myself to do some weird lines, or to jump things that aren't on a set distance, so we practice being "not perfect" - I think it is the ability to deal with things when they're not perfect, that sets a competent rider at a level apart from one that is scraping by or potentially a danger to themselves.
I feel that as they get more broke, I am usually moving them up a level, so even though I can get the perfect speed & balance and see a distance and help them get to it more easily, that is just part and parcel of having to jump bigger/more complex jumps. I still need to feel confident that if I royally screw up, my horse will get us out of trouble, and vice versa.
The worst feeling is coming into a big jump or complex with a horse that is not in balance, is behind the leg, or that is relying on you to do all the work. If a horse gives this feeling consistently, I will reconsider its career.
I usually sit up 5-10 strides beforehand and check our balance, then ride the fence accordingly (keep the rhythm and speed for a fly fence, or establish a coffin canter and elevated forehand fora complex).