THE SKIING IS EPIC this month, and it looks to stay that way right through March. But if you push your schussing as far into spring as possible, can you be physically primed for running and biking once it warms up?

"Definitely," says Steve Higgins, 46, a former pro cyclist who spent the winters of 1990 to 1994 as a coach for the U.S. Ski Team while entering a smattering of bike races during the summer. "I'd spend my winters on skis, then in April I'd join my cycling teammates, who had already logged about 6,000 miles of riding. But it never took me long to catch up to them fitness-wise, since I was already in great shape."

Today, Higgins still sticks to his ski-all-winter, ride-all-summer lifestyle while also running Zone 1 Sports Science, a Seattle-based coaching service for elite cyclists, runners, and triathletes. Over the past 26 years, he's developed a field-proven model of seasonal cross-training: Because he combines ski-boosting cardio, core, and general-strength workouts with 40-plus days on the snow each season, he's able to make a seamless transition to warm-weather activities.

"Skiing works your quads, hamstrings, calves, and glutes," says Higgins, who adds that these are the same muscles you need to push pedals, run trails, and stomp up mountains.

You, too, can get a jump on snow-free fun—without skipping any powder days—by following the three-week plan Higgins has laid out for us. His regimen involves three phases: muscle preparation, then strength building, followed by explosive power work. Get started now and ski till the mountain closes.

THE PROGRAM: Each day's workout includes five minutes of bicycle crunches and back extensions (a.k.a. Supermans—see The Moves for a description of the core and weight-lifting exercises), plus ten minutes of leg and hip stretches. On non-cardio days, start your workout with an easy ten-minute aerobic warm-up of your choice. For the dedicated cardio sessions, use this scale of intensity: Zone 1 = easy; Zone 2 = moderately hard, able to hold a conversation; and Zone 3 = hard, barely able to converse. If you're lucky enough to be able to hit the nearby slopes on the weekend, go out on a Sunday. That way your muscles will have enough time to recover from Friday's weight training.