In reply to yh001:
Endurance really divides into two main categories: Both important for route climbing (even for boulderers who climb longer boulders).
1) Stamina (also known as aerobic capacity or aerocap to training geeks).
Generally if you have good stamina, you have excellent recovery both on and off the wall, marginal rests feel better, so do repeated redpoint attempts.
Simple to train - 20 minutes on the wall on EASY gound, like many grades below your onsight level. Let's say you onsight 6c, you should be aerocapping at around 5+,6a. No interruptions. Yes, it's extremely boring to do this, climbing up and down autobelays is a good way of doing this training, or just traversing around the bouldering wall.
Note: The pump should be manageable at all times, if you feel you're getting pumped and can't get rid of it, make the moves easier. You should feel almost refreshed after it.
Quite hard to build up the stamina to a good level actually - expect to do this 2 times a week for a couple of months for your endurance to peak.
2) Power endurance.
Fun but also painful to train!
This is where training moves near your limit and lapping just below your limit come into play. The idea of PE is to be completely pumped for as long as possible shutting bloodflow to your arms and letting the forearm learn how to work when totally pumped.
Excellent article on this by Steve Mcclure:
https://www.8a.nu/?IncPage=https%3A%2F%2Fwww.8a.nu%2Farticles%2FShowArticle...
Note:
Is your profile up to date? If you're bouldering at V7ish (well done btw, V7 is hard!), and climbing about 6c+ this is quite a big disparity, and it might be worth looking at the other factors which have a major influence how you do on longer routes:
I.e. are you overgripping? Bouldering is about pulling really hard, route climbing is about pulling as little as possible and conserving energy, making each move as easy as possible.
Are you afraid of falling? Not being afraid and moving as fluidly as possible will make absolutely bags of difference to your climbing (Some time ago, I jumped from 6b+ to 7a+ just by working on the head and no training).
Do you avoid certain routes because they are too long, too sustained etc? Generally if you do more of them, you'll get better at them quickly.
As far as cardiovascular exercises - I don't do any personally, but who knows, maybe they might be helpful at some point? I just never ever feel I didn't complete a route because I ran out of breath.
Good luck! You'll experience massive gains soon as endurance improves very quickly. Enjoy!
Post edited at 18:42