WEEK ONE: Create a base
Starting with moderate fitness, you'll need just a week to build a strong foundation. Do endurance and interval work on a soft surface, like grass or a dirt trail, or with low-impact sports like cycling. Older hikers: Substitute brisk walking for running on endurance days.
WEEK TWO: Build power
High-intensity bursts build strength for steep climbs. This week, you'll fit more into a half hour with longer intervals and less rest. Increase weight during training hikes to strengthen ankles and knees. For a lower-impact workout, substitute 1/4- to 1/2-mile swims for running.
WEEK THREE: Make miles
Training over long distances increases endurance, and working eccentric muscles (those employed on the downhills) will prevent soreness later. Increase mileage on all distance training, but ease off interval times to recover from week two.
WEEK FOUR: Taper off
Reduce intensity to preserve energy for the first day of your trip. Do endurance workouts on flat terrain, and substitute pace training (consistent tempo and intensity) for intervals. Stop lower-body strength exercises, but continue working your core and upper body.
Perceived Exertion (PE) - HOW HARD ARE YOU WORKING?
Perceived exertion (PE) is a subjective rating of intensity: You judge how hard you're working. Use a 10-20 scale, with 10 being a brisk walk and 20 an all-out sprint. Fitness gains roll in between 13-15 for endurance; 16-18 for backpacker-beneficial intervals. Heart rate correlates to PE x 10.