Strength can be broken down into 2 SUB-categories.....force production and force reduction.
When looking at the "On Mountain" demands, one can obviously see that force reduction will take the cake when it comes to a greater requirement while we are sliding down the slippery slopes.
With all the terrain changes that we experience on the slopes, our "shock absorbers" (AKA legs) are in a constant state of force reduction (which is an eccentric muscular contraction).All that said, wouldn't it be enough to focus on the eccentric muscle action of any exercise?
While that would be a step closer to the functional
demands of a skier/rider, it still would not be enough.
The forces that we deal with on the slopes are tough to mimic in a synthetic environment (machine). To expose our bodies and muscles to gravity, momentum and ground reaction forces would give you the necessary stimuli for what you are asking for
To do this, you have to get off the ground. Add two legged and single legged jumps to your program and the results will speak for themselves.
I would also have to agree with everyone in regards to getting you out of the leg press and getting you onto your feet since that is where the best skiing/riding takes place!