cross-training effect

[spiderman]

Rip,

I'm confused about the correct language to use to describe the necessity and benefits of cross training. For example, my rock climbing ability is heavily dependent on my forearm and abdominal strength. My forearms have developed over the years but in order to have my abs in good enough condition I need to do sit-ups. If rock climbing benefits from strong abs then why are my abs not developed enough through rock climbing alone?

Thanks.

[Mark Rippetoe]

More importantly, why are your forearms sufficiently developed and your abs are not?

[spiderman]

Well, rock climbing must stress my forearms enough to cause adaptation. What I don't understand is that if climbing benefits from strong abs then why doesn't rock climbing develop strong abs. It seems like a paradox of sorts. How is this sort of thing usually described?

[Mark Rippetoe]

What measurement of your ab strength tells you that they are not "strong enough"?

[spiderman]

Climbs are all graded if I've been doing abs exercises I can climb harder things. When I'm climbing on overhanging rock, the sensation is that I can lift my hips and keep my hips close to the rock. This puts more weight on the feet rather than hands and lets me control body position better.

I would guess the phenomenon I'm describing is not specific to climbing. I'd think there are many sports that can benefit from a high level of strength in particular muscles that are not the primary muscles of the sport but the sport alone cannot actually develop that high level of strength in those particular muscles.

[Mark Rippetoe]

This is why barbells work for football. There reaches a point in sports of all types where the activity itself is limited in its ability to provide enough stress for further adaptation to take place, usually once you get very efficient at doing it within the framework provided by the activity itself. Then it becomes necessary to create stress not normally encountered in order that adaptation may continue.