We do much of the canter work in the school when the weather is bad. 20 times around the 20x40 changing rein every 4 laps and lengthening on long sides is approx 2000m, same as an Intro or PN.
Just had a thought, why not try him on Saracens equijewel if he's finishing tired, it worked a treat for one of our horses. You start off on two lbs a day and cut back when the optimum energy level has been reached.
Chocolate is a different horse on it these days!
I was going to ask about feeding/supplementation - getting horses fit isn't just about work, it's about finding a balance of energy in and energy out.
If you're finding a very different reaction in your lessons perhaps you need to ramp up the work in your schooling sessions at home? While hacking is great for fitting horses up generally, it functions a bit like jogging. (Although if you're schooling when you hack and/or doing a lot of hills etc. then it a more "all over" work out.) But good flatwork is more like going to the gym and provides different stresses on the system. It may also be he finds the lessons mentally stressful, in which case the work should be more part of his regular routine.
What you say about the cantering is telling. Obviously the canter is the most important gait for horse that jump for a living and you need to have one he can not only hold but also adjust easily. You should be able to start to "work" in the canter at this stage, not just do a short canter in the school. I've certainly got horses basically fit by cantering in an arena (sometimes the only option in a Canadian winter!) - just make sure, as said, you do lots of changes of direction and at least some adjustments of pace.
Horses don't have to be worked every day, but how much work needed for the individual horse to get fit varies a lot.
My TBs/TBx have just thrown themselves into work and always put in maximum effort, so actually needed very little work to get them and keep them fit at the level I needed. On the other hand my present horse is very lazy and I was amazed at how unfit he was with my usual work regime.
Lots of trotting is circles is hard work, and they will be fit - for trotting in circles. If you are galloping you need to practice galloping, or at least long canters. You have to raise the heart rate to - I think - 120 per minute (check with a vet book/fitness book) - to increase fitness. You can buy a heart rate monitor for about £100 from the Endurance equipment sites if you think this would be a good idea (if I was getting my own horse fit for eventing I think I would invest in this tool.)
He might need a bit of extra food to give him a bit more sparkle. He should be doing his work easily. He won't have lost any fitness over the Christmas break. Horses keep fit for quite a time, unlike humans - years ago snow and frost would disrupt hunting for 2-3 weeks and the break didn't seem to affect the horses much.
QR: Just a couple of thoughts from my point of view:
1. I came seriously unstuck last season getting my horse way too fit for an intro and all the pro's I spoke to subsequently said they do not get their horses 'fit' for intro or PN, that they use the early events as fitteners. By unstuck I mean so many time penalties for too fast that we had a visit from the Steward to (in his words) give me a rollocking!
2. I agree some horses and riders are not fit enough but from what I've seen it tends to be the 'larger' more unbalanced riders on 'larger' horses who frankly aren't up to it full stop - you could get them as fit as you like but the ability still wouldn't match the ambition....(I know, terribly controversial, but hey ho).
3. In lessons it can be very mentally tiring for them - B is pretty fit at the moment (for example we jumped today so he worked for an hour including doing a big grid finishing at a 1.20 oxer) - he was not sweating and was barely blowing. Contrast that with last week when we had a 45 min lesson all in walk and trot doing dressage and he was shattered by the end of it - he had to think one hell of a lot more! I would guess Polly's lessons ask a lot of questions he is not used to and therefore he is mentally as well as physically tired.
By March he'll be plenty fit enough for intro - I think working 6 days out of seven with 2-3 schooling sessions and a couple of hacks, with some canter work will do him fine. Just take note of how he feels XC and let him take things steady if he needs to!
I think so, if only because any decent instructor should be able to see where the horse is at fitness-wise and tailor the lesson accordingly, even if that means finishing 15 mins early or whatever. There are plenty of things you can do which are helpful but not exhausting exercises, in walk for example.
Yep and Polly is very good with stuff like that - a lot of the earlier sessions we did a lot in walk that were really very helpful and she always pulls up when she thinks hes too tired