OUTSIDE
Trail running is a pumped-up version of hiking. It works all the hiking-specific muscles mentioned earlier, but because it picks up the pace, it also builds tremendous cardiovascular endurance and power. Concentrate on your balance and coordination-when mastered, they translate into fast, smooth skiing.

INSIDE
Grapevine
You've likely done the grapevine before. Place your feet shoulder-width apart with your hands out front and knees slightly bent, and cross one foot over the other in a smooth, fluid motion. Start out moving slowly and build up to a fast-but comfortable-speed. Do three sets of 20 feet in each direction, with a 30-second rest between sets.