You don't need an expert to tell you that vigorous cross-country skiing is a good workout. Each and every muscle in your body—including the ones you smile with—will remind you after your first time on skis this winter. But the better you prepare those muscles before the snow flies, the less they'll complain later.

When it comes to Nordic skiing fitness, almost everyone focuses on legs and lungs. Makes sense; that's where much of the work gets done. But your upper body contributes, too.

The primary upper-body movements in cross-country skiing use the deltoid muscles to raise the arms to plant the poles, then both arm and core muscles to push downward and backward to slide the body forward. Several simple, easy exercises will help tone and strengthen these primary upper body muscle groups.

Lift, Repeat
With simple dumbbells, you can get very serious training. Jason Aziz, a certified strength and conditioning specialist for Concord Hospital in Concord, N.H., recommends two basic exercises: the pullover and the front deltoid raise.

• Pullover: Lie on your back (preferably on a raised platform or bench). Hold a single dumbbell behind your head with arms slightly bent. Use the muscles in your arms and core to pull the dumbbell up and over your head in a smooth motion, ending at your waist, then reverse the movement. Raise your legs with bent knees as you pull over the dumbbell to work your hip flexors. The weight of the dumbbell should vary according to your individual needs. Start on the safe side, with 5 pounds or less.
• Front deltoid raise: Stand with a very light dumbbell (even 1 or 2 pounds will make a difference) in each hand and raise your straight arms in front of you to chin height. Alternate arms and use muscle power, not momentum, to move the weight. This will work the opposing muscles.

For maximum benefit, mix it up. On occasion, use heavier weights in sets of 10 repetitions to gain strength. At other times, do more reps with lower weights to build endurance (try sets of 20 and work up from there). Do some sets with quick, explosive motions, and others as slowly as you can.

Olympian Preparations
Former Olympic cross-country skier Sue Wemyss, now the ski school director at Great Glen Trails in Pinkham Notch, N.H., recommends adding some simple exercises that don't require a trip to the gym.

• Chair dips: Face away from a chair and place your hands on the edge of the seat. With legs stretched out in front of you, lower your body toward the ground by bending at the elbows, then straighten back up.
• Supermans: Lie on your stomach with arms stretched forward. Arch your back to raise your arms and legs off the ground simultaneously, then return to floor.
• Planks: Rest on your forearms and toes, with arms bent at the elbows, and hold your body in a pushup position for 30-60 seconds.
• Situps and crunches

Fun Before the Freeze
Weight training and core exercises will definitely ramp up your cross-country performance this winter. There are also fun, outdoors things to do until you're snowed in.

According to Wemyss, flatwater kayaking (or canoeing or rowing) develops great upper body endurance. By using a shorter paddle with a wider blade and a high-angle stroke you'll get a much better workout for your arms, shoulders, and torso. If it's too late for this season, keep it in mind for next year.

Wemyss also touts Nordic walking, hiking, and running while using poles actively with each stride. "Pushing technique should mirror classic ski pole technique," she says. "To get the most benefit, be sure to plant the pole angled back and push so that your hand is passing by your thigh. Arms should only have a slight bend and not collapse when you push. The longer the push on the pole, from start to finish, the more muscles engaged. This activity is also great for cardiovascular [exercise]."