What I have always looked for is a type of conditioning that will carry over well to many different movements. As you know, an elite runner will gas out after a short ocean swim if he is not conditioned in swimming so the problem in not just having a great CV system to deliver to blood to the muscles but having the muscles conditioned to the efficient use of fuel IN THAT PATTERN.

The treadmill is a bizzar thing to me in that is seem to really screw up something that is so natural...rather than using your posterior chain to drive yourself forward your foot strikes a belt that mechanically pulls it back, thus taking your posterior chain OUT of the movement...what the hell is that?

I think the ultimate athlete that is not specialized to a certain event has to take a page from the crossfit book and be fit in serveral different patterns.

IMO the single best form of conditioning that casts the widest net of effective carryover is the KB snatch...people complain about spending 120$ on a kettlebell....try spending 2-3000$ on the only other equiptment that comes close Concept II or a Versa Climber.

The sport I am training for is best supported by bouncing between KB and a Nordic Track which is as fine a piece of cardio equiptment as you can find along with the Erg and Versa Climber