At the risk of getting all Tom Jones on you, I know that you know that what goes up must come down. That is a gravity thing, and it is pretty cool. It means when you go up a trail you get to come down. It is what MTB Enduro is based on. Ride up some road or trail and then time yourself coming down a section via gravity. I am sure there is some pedaling involved, but it is basically a gravity kinda thing.
Downhill is a gravity dominated activity. Unlike MTB Enduro, in DH there normally isn’t any hiding behind your ability to pedal up something. It is not like there isn’t any fitness necessary – oh there is. It is a bit like people’s perception of Motocross. The perception is that the bikes are so technical, that all you do is clamp yourself on to the things and they do the work for you. If you have not ridden a Motocross bike or a DH bike, you have no idea what you are talking about. They might not require the waif thin thing that XC racers or road racers are, they might not require the pure aerobic ability that those disciplines do. But, they require the ability to operate at a high heart rate and a ton more core strength and upper body involvement.
But, the biggest difference is that those sports (DH and Motocross) while dealing with the upper body strength and the core strength issues, while your heart rate is pegged at a near anaerobic level, they also require that you have handling skills that are never required on an XC bike or a road bike.
That handling skill and resulting amazingness is what makes watching those sports so much fun. I mean it is exciting to watch the pure athletic aerobic ability of an XC racer or a road racer. But, it is the death defying handling ability of DH racers or Offroad motorcycle racers or Motocross racers that is so fun to watch.
Take a look at these video’s and you will identify with what I am talking about. In the end, it is all 2 wheelers so it is all good.
The above video shows the skills required to be a DH racer. This is a practice run, so there is a lot of effort to be stylish. In a real race run, there is not really any coasting and certainly another 20% of pace effort.
That video is from the Ironman GNCC from 2013. A crazy hard 3 hour race up and down the mountain, over and over and over.
There is a bunch of really good slow motion in this video, showing how much body language it takes to make a mountain bike work in that terrain.
Pro Motocrosser’s workout on youtube.