As anyone here knows from getting on various obstacles, the grip technique and strength needed for the rings, steps and bars – requires an entirely different grip and type of grip work from ropes.
I was browsing an article about how to kill the next obstacle course you’re on by an unnamed trainer in an unnamed publication. The first section for “advice” was on the rope climb. The advice was inadequate and misleading at best. And my evaluation of this advice is from first- hand experience in working on this type of grip work.
So the advice to get better at ropes is to work on various pull-ups, chin-ups, and TRX work. As I said and you should be able to see, inadequate! Sure, upper body work is imperative for obstacle course training – you do need to pull your body weight up many times over and have the hand strength to hold on. But none of this makes your power grip better for rope climbs, rope hangs, rope swings, door hangs, cylindrical holds, etc.
I found this grip referred to as a power grip, so that’s what I’ll call it. Professor Alan Hedge of Cornell University indicates that the power or cylindrical grip provides the maximum gripping force that the hand can generate. The only two exceptions that change this are the wrist orientation (deviation of a neutral wrist position) and the thickness of the gripped object (very narrow or very large item).
In Ninja Obstacle Course training many items are vertical, so to say that working on pull-ups will help you kill rope based obstacles is a bit overreaching. To get stronger and better with the power grip you must progressively train on the very obstacles that use this grip. Get up on those floating doors or ropes and start by hanging; work the cylinder grips in succession with the rings and other grips; climb a rope hand-over-hand from a seated position keeping the heels on the ground as a pivot point. Build up from there and progress the movements.
You get the point, work on what you need to work on! Pull-ups get you good at pull-ups and are awesome to do. Your hands will strengthen and toughen up, but, only take you so far and have some carry-over.
I have personally sought out the advice of those that do it and have done it for years – I trust the trainers and coaches at the Ninja Park. So seek out those at your local ninja gym or those that you might follow and get their advice.