Start with a 10- to 15-minute jog. The Kostelics hone their balance and agility by running along sea cliffs overlooking Croatia's Adriatic coast, but any uneven terrain will challenge your balance so you can better steady yourself on the slopes, says Guerriero. He recommends a run along the beach or, for the landlocked, a grassy field or hill with lots of natural obstacles.
Before the advent of fitballs and balance boards, Ante developed this rustic drill to sharpen balance skills. Standing on one foot, with your arms out for stability, balance yourself on a log and then jump forward, landing on the same foot.
The routine: Repeat five times on one foot, then switch to the other foot. Aim for three to five sets on each side. As this becomes easy, you can simulate a ski run by continuing on for a minute or two, alternating legs every few jumps.
The payoff: Log hops develop explosive strength and coordination, says Guerriero. "The motion is similar to what you have to do on the slopes. If you don't have a log, use a balance beam or snow berm. If you need a less challenging surface, draw a line in the dirt and concentrate on landing right on top of it.
With hands shoulder-width apart, lean forward and hang your arms toward the ground while holding a twig or taut rope. Keeping the twig in front of you, jump up and over it, as if it were a jump rope.
The routine: Begin with five sets of three to five reps. Focus on completing the move cleanly. Says Guerriero: "Technique has a tendency of falling apart if you go too fast. This move takes some coordination and flexibility. Don't be afraid to start by jumping over a stationary rope on the ground and then work up to holding it yourself.
The payoff: Expect this plyometric move to increase your power, leg strength, and coordination. "You need explosive lower body strength to handle the g-forces and rigors of skiing, says Guerriero. This exercise will get you ready for bumps and big mountain skiing.
The Kostelics grew up using logs and rocks as natural weights. You can do the same by holding a large tree branch in both hands and doing a shoulder press/squat combination. If you don't have a tree branch, hold a large rock (of equal weight) in each hand. Stand with your feet hip-width apart, and squat down until your knees are bent no further than 90 degrees. Hold your torso straight and centered over your hips. Press through your heels, and come back up to standing. Repeat five times. Janica increases the intensity of this exercise by balancing on a four-foot-high sawhorse. You can balance on a rock or log.
The routine: Aim for five sets of five reps with 10 seconds rest in between. As your technique improves, increase the load by stacking on bigger logs or holding heavier objects.
The payoff: "When you're skiing, you're fighting against gravity and speed. To do that you need strong legs, says Guerriero. This exercise is one of the best ways to bolster your quads.
With this move, the Kostelics prove you don't need fancy gym equipment to tighten your abs. Hang from a bar or tree branch with your arms straight. Keeping your torso still, lift your toes up until they touch the bar or branch.
The routine: Try for five sets, holding for five seconds each time. If lifting your feet to your hands is too difficult, begin by raising your knees (with legs bent) to 90 degrees. Then progress to holding your legs out straight, at a 90-degree angle from your hips. Finally, try to lift your toes all the way up to the branch.
The payoff: Core Strength. "The stronger your core, the better you can handle fast changes of direction on the slopes, says Guerriero. This exercise builds strength in your torso and back as well as your upper body.