Everybody knows you should not increase your performance to rapdily in climbing, because your strength grows a lot faster than your tendons and you risk injury.
So how should I train to let my tendons keep up?
Everybody knows you should not increase your performance to rapdily in climbing, because your strength grows a lot faster than your tendons and you risk injury.
So how should I train to let my tendons keep up?
There was a study done along these lines in the Journal of Strength and Conditioning Research in 2010, where they did strength training for 3 months and then detraining for 3 months to measure the adaptations.
The basics were that strength was measurably increased after 2 months, size didn't start changing until near the three month mark, and the tendons did not start responding to training until near three months as well. It happened in reverse as well, muscle size reverted within a month, tendons in two months, but strength persisted for another 3 months.
The unfortunate thing is that you can't really specifically train a tendon, you just have to wait for them to catch up to the muscular training. I don't have any direct climbing experience, so I can't really advise you on the training progression you should follow, other than be aware that your tendons will somewhat lag behind your muscle development (At least until you plateau your training). I wasn't able to find any studies indicating if the tendons ever "catch up" to your muscular development cycle.
Note: This answer pulls from a variety of sources, books, observations and personal experience and opinion, none of which are cited scientific studies
I'm going to address this in two parts, how beginners tend to / should progress at climbing (from personal experience and observation) and tendon strength / training (mainly from books and a bit of personal experience).
Everybody knows you should not increase your performance to rapdily in climbing, because your strength grows a lot faster than your tendons and you risk injury.
I'll try and keep this succinct because honestly I could talk for hours about this, and I'm going to assume that you're a beginner, or just not very experienced (if I'm wrong about this, my apologies, feel free to skip to the next part)
The natural instinct for most beginners is to want to climb the hardest thing possible and so attempt to advance through the grades as quickly as possible; the problem with this approach is that they very quickly hit a skill ceiling and assume that they need to get stronger to improve, training to do more pull ups, or even chasing the oft sought after one arm chin. This is particularly true with males, whose natural instinct when climbing is to mimic a gorilla, grabbing and pulling on everything in sight.
This is a mistake.
As your climbing technique improves, as you learn how to position your body to better take advantage of the shape and position of holds, and learn how to take smaller steps and move your feet more instead of throwing for holds, you'll find that you naturally grip less and put less strain on your fingers, joints and tendons.
Before worrying about tendon strength, look at your technique. If you're into slab climbing, learn how to shift your bodyweight so you can get up routes just using holds to assist your balance instead of relying on them to pull yourself up the wall. If you're into climbing overhands or roofs, learn how to toe hook and twist to keep your hips close to the wall and maintain tension instead of treating the route and holds like odd shaped monkey bars.
If you're tall, really work on your core strength (I'm 6' 5" and 220+lbs, an unpopular truth is that shorter climbers have it a bit easier than taller ones, shorter climbers can always get stronger, taller ones cannot decrease limb length, well, maybe if your name's Aron Ralston...), being able to control your body and hold it in certain positions will greatly improve your climbing ability.
I had a break of almost 2 years from climbing, and when I went back to it, I knew my body wouldn't be conditioned to the point it was when I stopped, so I went with the intention of enjoying the movement of climbing, finding ways to send routes with a minimum of effort, placing my feet delicately and climbing as quietly as possible. By doing this I was able to immediate go back to climbing 3 - 4 times a week without suffering any joint or tendon issues at all.
Everyone I teach to climb or boulder, I advise to do the same. Don't be in a hurry to chase grades, learn to move better, enjoy the nuances of each route; if you climb a route and there's a particular part where you feel off balance and have to snatch at a hold, work at it and find a way to make a smooth transition. For me, climbing is a type of moving meditation, by focusing on a boulder problem and searching for the ideal way to climb it, it's very easy to lose a sense of time and your surroundings, to enter a flow state.
It's not always easy to get this across to someone who's just started and wants to send the hardest problem possible, but if they do understand it, I've found that they actually improve much faster and enjoy their sessions a lot more that those who go away and look at the fastest way to max out their pull ups.
So how should I train to let my tendons keep up?
I enjoy reading about old time strongman training, and one of the things that I understand they used to do, that very few people seem to talk about now-a-days, is train for tendon strength.
I'll admit I haven't exhaustively searched around for information on tendon strength training routines, but my understanding is that there are two specific elements to it, heavy weight and high reps.
I remember reading how old time strongmen would do heavy supports as part of their training, getting under a bar loaded with 150% of their squat 1 rep max, and just standing up and holding it for time, or pushing or pulling against a non-moving bar, isometric style (I think this is something that Louis Simmons does with the Westside lifters, though not specifically for tendon strength (with a quick search, I actually couldn't find any information from sources I know about isometrics for tendon strength, but it does lead nicely onto...)
For climbers, there's fingerboard training. Fingerboard training is literally hanging from your fingers from a board made to mimic various climbing hold positions in order to strengthen your fingers and tendons in general. This is the heavy weight part of tendon training for finger strength.
I first heard about high rep training for tendon strength when I read through Convict Conditioning by Paul Wade. Assuming you don't want to spend money to read the program, in order to progress from one exercise to another, he suggests you meet a minimum number of reps, for press ups, to move from exercise 1 (wall press ups) to exercise 2 (hand elevated press ups), he recommends being about to perform 3 sets of 50 reps (he also recommends using this as a warm up as you get stronger and progress). The belief that this was to train the tendons was confirmed in a blog post by Jason Ferruggia on bodyweight training (no link, it's probably been taken down by now).
More recently, Christian Thibaudeau wrote a very interesting article on the topic of tendon training.
Something that I know a few fellow climbers have had great success with is finger extension for high reps using something like ripper bands, or even just elastic bands, wrapped around the fingers throughout the day, to help with suspected tendon issues. Along the same vein, one of the warm up exercises I put people through before climbing is repeated tiger claw finger / hand movements, which I've found to help with warming up the fingers, and to prevent "finger ache" following climbing sessions.
Hopefully within my essay of an answer you'll find something helpful.
As a slight aside, recently at the Oscar's, where Free Solo won the Oscar for Best Documentary Feature (if you haven't seen it, you should), someone handed Alex Honnold a device for measuring grip strength, he pulled 75lbs with his right hand, 95lbs with his left. I recently tried one of these in a sports science experiment for climbers and pulled 180lbs with my right, 165lbs with my left.
I found this interesting because there is no way I could pull on half the holds he can during his free solo of Freerider up El Cap, and yet it would appear my grip strength is far in excess of his. Makes you wonder just how tightly he grips holds while climbing...