It starts with a gentle soreness in your lower back or quads, after your second or third ski run of the year.
By lunchtime, each turn increases the burn in muscles that haven't been used this way in months. By the end of the day, walking to the car causes screams of protest from hamstrings, upper legs and thighs, and you wonder, was skiing this hard last year?
Skiing and snowboarding are intense aerobic and anaerobic activities, which can burn about 375 calories an hour, depending how vigorously you attack the mountain.
But your first tracks of the year don't have to leave you feeling like you're in traction the next day.
Fitness experts and ski instructors say skiers can greatly ease their transition into skiing, and have a much better season, with an exercise routine. And the time to start is now.
"Since people don't ski year-round, it's that kind of activity that you need to do some sort of off-season training for," said Greg Wiggins, president of local company AlpenQuest, who has been teaching ski conditioning courses for 30 years.
"Skiing and riding are pretty athletic endeavors. I think a lot of people probably underestimate the physical nature of the two sports," said Michael Ray, wellness director at the YMCA of the Pikes Peak Region's downtown facility, and an avid skier.
Many skiers, those who bother with pre-season conditioning, focus on the legs, and experts say that is important. Skiers should build up their quadriceps and hamstrings, while snowboarders should focus on calves and shins.
But experts say strengthening the "core" - the abdomen and lower back - and working on balance are much more important, whether you ski or ride.
"I certainly don't want to minimize having very fit or strong legs, but without the core, which is the foundation of the body, you're definitely not going to be at your peak in terms of physical conditioning," Ray said.
About 12 weeks before he plans to start skiing, Ray ratchets up his workouts, supplementing hiking and mountain biking with strength training for the torso, weight lifting on balance boards and workouts with balance balls.
He also recommends skiers take a ski conditioning class, or "boot camp"-style class, offered at many local gyms.
As the season approaches, Winter Park ski instructor Julie Pierce focuses on interval training, quick bursts of exercise to get the heart rate up, to mimic a day of skiing. She agrees skiers need to work on their core for strength training, and that too many build up their quads while neglecting other key areas, like the hamstring.
"I may not be able to leg press as much as a guy who's way bigger than me, but because my stomach is fairly strong, I can hold my own (on the slopes)," said Pierce, who was Colorado Ski Country USA's instructor of the year last season.
Before the first day on the slopes, skiers should take it easy for a few days, she said. They should stretch before starting to ski, take lots of water and not be afraid to call it a day early. There's a lot of ski season left.
"If you over-do it, it's going to take you twice as long to recover," she said.
And don't feel bad if you find yourself in recovery mode after the first day. After all, exercise in a gym can only prepare you so much.
"It's really good for people do to programs, but sometimes you just have to ski," she said. "People shouldn't get discouraged if they ski their first day and they're sore. They used their muscles, and they should (be sore.)"
Said Wiggins, "They're going to be less sore if they've been working out, I can tell you that."
Many Web sites offer tips and exercises for ski conditioning. Some of the better ones are ifyouski.com/health/ and abc-of-skiing.com/ski-fitness/ski-fitness.asp, or search for "ski conditioning."
EXERCISES FOR SKIIERS AND SNOWBOARDERS
Cycling: Hit the trail, or a stationary bike, for a cardio workout that strengthens leg muscles you'll need on the slopes, and do quick intervals to condition for the sudden burst of energy that is skiing.
Squatting: Squat and walk sideways, placing weight on the inside of your legs, to mimic skiing movements.
Balance: Stand on your toes and bend one leg back and hold it. Stand on your toes and lean to the left and right and hold it. Try a Pilates class.
Jumping: Hop from side to side over an object, with knees bent, landing and springing on one foot at a time.
Stretching: Stretch for 10 minutes before exercising and hitting the slopes. Yoga is great for improving flexibility for skiing.
Rollerblade or skating: You will use many of the same muscles as skiing, and, more importantly, work on staying upright with your feet strapped into foreign objects. Just remember, pavement is a lot less forgiving than snow.