I have recently teamed up with an elite level youth climbing team from Massachusetts. I have a group of kids aged 10-17 who will be training out of my gym. General Fitness will be done with me twice a week for about 30-50 minutes depending on their age.
I was wondering if you could make a suggestion based on your own experiences as to some "must includes" and maybe even a "mustn't include" as far as training for climbers...youth specifically.
This will have to be a bit general.
They will get enough pulling already so no need to include that.
I would mainly concentrate on whole body movements aimed at core-to-limb integration: the more weight they can pass through the core to the feet (by way of body tension) the less weight is supported by the hands. Consider also the concepts of flexibility and coordination.
In this context the Turkish Get-up and Overhead Squat are quite good. The TGU can be done with flexibility as the focus or with strength as the focus. And you can work grip and enforce "presence" by doing them with a KB in bottom-up position. Both these movements are also good for shoulder integrity, which is often the weak link.
For raw strength the Deadlift is fine, probably no need to do any heavy Squats but Goblet and Front Squat for range and posture and hip flexibility are fine movements for climbers.
Finally, SOTS Press, mostly for posture, also shoulder health and because no one likes them.
The big thing to consider with young kids is connective tissue: it's not well developed, muscle develops 3x faster, so it is easy to over-power tendons and ligaments by doing too much strength work too quickly. They will do just fine with light to medium loads for a long time, and the younger the trainee the longer you can wait before strength will become a limiting factor and need to be addressed.
You will be surprised by the power-to-weight ratio the kids have and should do everything to preserve it so again, heavy loads are not needed or advised. Any circuits - the "Big Five 55" comes to mind - that work strength-endurance and CV power-endurance are also good. Anything they do to improve aerobic fitness will speed recovery day to day and when doing routes.