You’re wise to look to injury prevention by using strength training. We’ve had great luck with single legged exercises for mountain sports. Things like the box step up, split squat and lunge. All these sports rely heavily on your hip stability. These single leg exercises have a great training effect on hip stabilizers while they are also training the prime movers that are responsible for locomotion. Two legged lifts like back squats and deadlifts, while good general strength, are not as well suited for mountain athletes as the single legged stuff.