In addition to leg strength, you need upper body strength to get down the mountain. Developing your upper half will help you master your turns, dodge trees and other skiers, and reduce the risk of injuries — shoulders, back, arms — that result from falling. This piece goes through a simple upper body workout for skiing.
A wise man once said: “You’ll look a whole lot better coming down the slopes if your arms aren’t flailing and your skis aren’t controlling you.”
And for cross-country skiers, upper body strength is calculated to be half of what gets you up a hill.