Second, I use the word "Sport" loosely and mostly because it makes the title sound nice and might trick you all into thinking I am well-read and witty.
Here we go...
I went to college in Colorado. I was able to climb rocks almost every day. Blah, blah, blah, it was great, then I graduated, now I've been living in Maryland again for over a year. Since moving back to Maryland I have probably spent less than 20 days rock climbing and at least 200 days gym climbing. Compare that to the year before, in Colorado, where those figures were pretty much flipped. In the past 2 years the pendulum has swung dramatically, giving me what I think is an interesting perspective (not unique, just interesting). Especially as I look forward to my imminent move BACK to Colorado in 2 weeks, where the pendulum will hopefully begin to settle somewhere in the middle.
It seems obvious to me, but I'll go ahead and say it just so we're all on the same page:
GYM CLIMBING AND ROCK CLIMBING ARE DIFFERENT.
(Okay, I shouted it. Because every so often I need to remind myself too.)
Sure, they're pretty similar: You grip, you pull, then repeat, and I'm sure your feet are probably doing something too. Though I would submit that this is where the similarities end and the two activities diverge, sharply.
I recently had a conversation with my girlfriend who was frustrated because she didn't feel like the gym was preparing her properly for outdoor climbing. She went to the New River Gorge, was working on a certain grade, came back to the gym, got stronger, went back to the NRG, and was still working on the same grade! How could that be?!
My response: How could that NOT be?
Training in the gym and then expecting to be a better rock climber is like spending hours perfecting your Guitar Hero skillz, picking up a real guitar, and expecting to be able to play the same songs. It just doesn't work like that. Guitar hero might help with your coordination and finger dexterity, and you need those things to play guitar, but you are missing everything else. And it's everything else, that makes playing the guitar, playing the guitar.
Training in a gym will make you strong. It will help you with basic sequencing. You will learn general technique and grip positioning. You'll learn how to try hard, how to heel-hook, how to toe-hook. You get the basics. And you NEED the basics, but what you're missing is everything else. The uncomfortable holds, the cryptic sequences, the minuscule foot holds, the weird body positions, the awkwardness, the fear, the SUBTLETY. It's all of those things that make rock climbing, rock climbing. It's all those things that the gym won't prepare you for.
Routesetters are constantly berated for how their work compares to rock climbing:
"There is NO WAY that is 5.9!"
"That would be 5.12a at The Red!"
"Yeah, but you would NEVER do that move outside!"
"All the grades in here are SO sandbagged compared to outside."
"All the grades in here are SO soft compared to outside."
"Yeah, that would be V2 at Horsepens."
"Dude, that V8 would be V11 at Hueco!"
"Bro, have you ever even BEEN to The Red!?"
Hey guys...chill. It's different. If you want to go rock climbing, go rock climbing. If you want get strong, train for comps, not lose all of your technique, have a good time, get pumped, satisfy your addiction until your next trip, flex at the girls on the treadmills, then come on in to the gym.
I hope it doesn't seem like I am bashing gym climbing, because I LOVE gym climbing. Hell, I even like comps! But I recognize and accept that it is not rock climbing.
I've been training in the gym for the past year. My body is stronger than it has ever been. But my last few bouldering excursions have been frustrating. My mind is weak. I feel uncoordinated. I have trouble seeing and feeling the body positions. It takes me longer to adapt to novel movements. I don't trust my feet enough. The list goes on... The only way I can improve these things it to climb on rocks more. For the ExPhys nerds, it all goes back to the SAID Principle. The Specific Adaptation to Imposed Demands. The body can only adapt to the demands you place on it and it adapts very specifically. Rock climbing and gym climbing are different stimuli and you body adapts accordingly.
Is this horse dead enough? I sure hope so. I'm going to go work on my van.