How do I improve climbing stamina for rope climbing?

Does your gym have circuits training wall? If so, maybe try to do reps of the circuits starting from middle to easy grade so that your body starts to learn the new condition of climbing. Do you drink enough water during the day, a night before climbing and during the climbing session, keeping your body hydrated? This helps. Getting pumped is a function of Lactic Acid building up in your arms, maybe forearms in particular. You can delay  the formation of Lactic Acid by training consistently, pushing harder until your tip into a higher level of fitness. Do you effectively position your body while climbing? Climbing is not only about using your upper body. Climbing is about distributing your body mass across the whole body while keeping your centre of gravity close the wall. This breaks the tension created by geometrical and steep walls. Maybe take notice on your footwork while climbing. It really helps to become a better climber. Do you read the route before touching the starting hold? If not, then work on your mental skills in reading a route and climbing it first in your mind. This enhances your body coordination and you appear climbing with grace. Always watch other people climbing the same route for everybody brings a different and novel form of idea for you. Maybe try dumbbell wrist curl workout that targets your forearms.  Finally before climbing, bring a happy memory to your mind and feel the happiness. Climb for fitness, health and beauty . Wish you all the best

I recall the first time I had to lift 2 full length climbing ropes with one arm for an over-hanging rappel (to descend from a 2-3 pitch climb). You just have to climb lots. Gym climbing alone won't do it. It's the difference between sprints and a marathon. No one can do it for you. You not only have to get experienced in face climbing up also crack and counter force climbing. Nothing like a newbie who claims to climb 5.10 and can't get up a 5.6 chimney. In roped climbing, you need to understand the difference (in the USA) between a rating and a grade. A rating is merely the hardest move on a pitch. The grade is a measure of over all sustained difficulty. This latter is an issue of stamina. Bouldering and short climbs only prepare you for short climbs. You have to do longer climbs. Climbing lots of Grade Is won't prepare you for a grade IV. For a couple decades, I had a massuse. Now I massage her. She has terrible foot problems (you wouldn't believe). Climbing (cracks and finger locks) allow me to give her a better massage than her professional colleagues. I hate to see her in her pain.

Look up "ARC training". Right now you need to develop more comprehensive capillary penetration in your forearms (and increase mitochondria count). This is accomplished with low intensity activity for prolonged periods of time- at least 20 minutes. You can do this by running laps on a route (assuming you have a very patient belayer), barring that your best option is to traverse. You want to avoid any breaks and try for at least 20 continuous minutes of climbing, you should be lightly pumped but not the deep painful pump you're probably experiencing when roped up. You'll know that you're exercising at the appropriate intensity when you're breathing hard and sweating but not falling off because of forearm failure. Once again, it's very important that this is done at the right intensity level, if you go too hard then the muscles expand, eventually cutting off the blood flow and forcing your body to use anaerobic processes to generate energy.

It's not just stamina. Sure you need strong fingers and arm muscles to climb sport routes or even steep trad routes. But you have to combine your physical training with technical as well. You need to climb smarter. Last weekend there was a bouldering competition at my local gym and I was amazed at how easily the female champion climbed the routes. She just nailed it with what looked like no effort at all, only by moving her body much more efficiently than all the others, who simply couldn't do it because half-way through they were exhausted and pumped. So, again: sure this girl is strong, specially her fingers. You could see it. But there was a another girl who looked (and probably was) even stronger, and she didn't get close. But what really stands out is how you position your body so as to require minimum effort on your arms.

Best way to regain stamina is... climbing regularly. More specifically: climb 2-3 times a week for 2h warm up for about 15-20 minutes slowly progress difficulty in order not to get too tired too early series: as long as you can on easy ways try to relax your hands very often. Do not squeze hard! Try to use good technique relax for 3-5 minutes if you have access to short ways only try to climb up and then down. If you still have strength repeat without rest if you fall, go down. Do not rest hanging (it's waste of time) Do not forget to do some exercises after training - push ups, pull ups, something for your stomack muscles, core muscles... Get a proteins shake after training. Let yourself at least one day between your training to regenerate.

Bouldering is just a different style of climbing.  Give it time and the stamina will come. A few things to think about...  Technique is really important to avoid the pump.  Climb slow and deliberate.  Straight arms, good footwork, push with your legs more than you think you need to, etc.  I'm guessing you know all that, but sometimes it's easy to forget after bouldering for a while.  Also, do a solid warm up on 3-4 easy routes.  You want the muscles primed before you start pushing yourself closer to your edge. Does your gym have a hangboard?  Use that, too.

I was recently discussing this with a friend of mine (who also happens to be a paraclimber for England) her answer was that it is the easiest thing to train.  Quite simply don't stop. When you're tired and your arms hurt and you want a rest, don't. Climb until you fall off, only then do you know you're squeezing as much stamina as you can out your body. Some people do circuits, some do laps, others just go to a bigger wall! Good luck!

This will make me sound like a meat head, but I wish I would have been taking pre-workout like pre gym or c-4 explode. Just recently been using them and they significantly improve your stamina...in an insanely unnatural way ha ha.

When warming up I would always traverse the length of the gyms I was in, this helped in that not only was I climbing a long distance but it was easy climbing. When in college It was a small gym and about a 1/3 of it was an overhanging wall, so I would avoid that.