cross country skiing... best workout of them all. Zero impact, all muscle groups worked and cardio like you wouldnt believe. And an average 200 # guy can burn over 1000 calories per hour. As much as I like cycling, xc skiers are the fittest athletes in the world.
Yeah, cross-country skiing is an incredible workout. The highest V02 max (a measurement of how well your body can take in and use oxygen during a workout) ever was from a cross-country skier.
I don't think its fair to say that any one sport is the "greatest workout of all," though. The best way to go is always to have a mix of sports and activities.
XC Skiing is great, its a lot of fun and a full body work out. man I need to do some upper body work so I think I'll try to get out this year. Also time to take a skate lesson and gear up for skate skiing.
It really depends on the course. I Know after a long road ride I am drained but there are also occasions on the dh course which is a large distance shorter I am drained.
To get an accurate Idea of which is better for your fitness and health you have to take care of some variables first, this mainly being The Distance of the course and the intensity of the ride.
If your going on a leisure ride neither are too substantial but comparing the two as an all out effort I do believe DH is more physically demanding. On the same length course The DH rider will have a tougher time and a more intense workout. Although road biking is hard it isn't as hard in a shorter ride like DH is.
So IMO DH is better for your health pending you are riding hard.