Twenty-five years ago, the training regimen for World Cup cross-country skiers was largely cardiovascular. But that was then. "Now it's like the NFL," says Andrew Gardner, head coach of Middlebury College's Nordic ski team. "Size, as in muscle mass, is going up—but speed isn't decreasing." Training specialists like Gardner have learned that a hybrid approach, which mixes strength training with a cardio workout, is the best way to ramp up performance. And this technique, he adds, proves just as beneficial at an amateur level. The key is to focus on muscles not typically used on a daily basis to create a feeling of groundedness and control when it comes time for a glide through the woods.

TAKE A HIKE  A sore back is one of the most common complaints of beginning skiers. "This is really a matter of trying to overcompensate for lack of balance," says Gardner. Start by doing what you might already be doing if you're reading this magazine: take a hike. But add some structure to maximize results. "When you're walking on a sidewalk or carpet, the muscles that control balance in the lower leg-the microfacia-don't get used very often," says Gardner. Treading over uneven terrain, however, will firm your footing when on skis—and help prevent injury. Do a slow and easy hike to build capilarization one day, which will "increase the oxygen-carrying capacity of your body." Follow that with a high intensity romp with short intervals. Go hard for three minutes. Then rest for a minute. Do it five times. "This builds strength in your legs and increases your ability to continue at a high [lactic-acid] threshold."

WORK YOUR CORE  Build up greater core strength in the gym with what Gardner calls the medicine ball workout. Sit on a physio ball with a partner and perform overhead tosses with medicine ball (like a soccer throw-in) back and forth. "This works your abdominals, your obliques, and the two columns in your back," he says. Do five sets: one minute on, one minute off.

STAY ON BOARD  From here, move on to the balance board, an easy-to-find, simple-minded contraption consisting the of a non-slip board that rests atop a cylinder (www.vew-do.com). Start by moving side to side slowly trying to stay on for 30 seconds. Rest. Then shoot for a minute. After that, do it while holding a medicine ball.