Headed for the Mountains
Join Date: Oct 2009
Location: Squamish, BC, Canada.
I'll bite. I'm an endurance coach for runners and skiers so this falls close to my wheelhouse. Without knowing a whole lot of background info, it seems likely that the simplest/obvious answer might be what you are looking for - more time on trails. I respectfully disagree with the suggestion that high weight/low rep exercises are what you need. Consider what you are training for: LOTs of body weight reps, over many hours.
Spend more time hiking (or better yet running) on trails. If you are doing two, 5k runs per week, get that up to four per week. Then get build the distance to 10k and so on. You don't have to run fast, in fact, it should be at a conversational pace (power-hike the hills). It should be on rolling trails as much as possible.
Uphill hiking with a weighted pack is a good suggestion but should be a component of the training program, not the entire program. One 1hr uphill session per week would be a good start. If it's not obvious, dumping the water/rocks/whatever at the top is ideal because it saves your form and more importantly your joints for the hike (or run) down.
The stair master is great doesn't replace time on trails. As you are building up running volume, keep at the long hikes on your weekend. Keep the strength routine in there as it doesn't hurt but I'd advise to keep reps high and weight low to build endurance.
Training for the New Alpinism is definitely a good suggestion.