Skiing isn’t an easy sport, and it can be tough on your body — especially if you’re out of practice. Ski-specific stretches and exercises can help improve your strength and mobility on the slopes, hone your reaction time, and reduce your chance of injury.

The Nicholas Institute of Sports Medicine and Athletic Trauma (NISMAT) focuses on understanding how the body adapts to the physical stress of exercise. NISMAT suggests that you start the following exercises at least three weeks before your next ski trip.

These five exercises will help you stretch and strengthen key muscle groups for a more successful ski season. Be sure to check with your doctor before beginning any new exercise program.

This stretch works well in the morning before skiing, as well as during your three weeks of pre-conditioning. Lie down on a mat on your back. Bend your left knee, and bring it across your body so that your left leg moves over your right leg. Your left leg should rest on the floor on the opposite side of your body. Then tuck your left ankle under your right leg. Your left knee should touch the floor.

Hold your left knee down with your right hand, and extend your left arm out to the left side diagonally. Hold the pose for 45 seconds. Then repeat in the opposite direction.

For a modified version of this stretch, you can sit on the floor or a table. Extend your left leg straight on the floor in front of you. Bend your right leg and step your right foot over your left leg.

Lock your left elbow across the outside of your right knee. Rotate your torso to the right. Hold the stretch for 45 seconds. Repeat on the other side.

This exercise stretches the soleus muscle of your calves. From a standing position, place your hands against a wall and step forward with your right foot. Keep your left leg back, with your left knee slightly bent. This pose stretches the calf on your left leg.

Keep your left heel in contact with floor and lean forward with your hips. Hold the pose for 45 seconds. Then switch legs to stretch your right calf.

This is an isometric exercise to strengthen your quadriceps. Stand with your back facing a wall. Bend your knees at a 90-degree angle, and position your back flat against the wall. Keep your lower legs perpendicular to the floor and be sure your knees do not go out past your toes. Hold the pose for 30 seconds. Then repeat for three sets, resting for 30 seconds between each set.

As you continue this exercise in the weeks before your ski trip, you can progress in difficulty. Try holding the stretch for five seconds longer with each session. You can also increase the difficulty by bending your knees at a 45-degree angle.

Be sure to keep your back flat against the wall and your lower legs perpendicular to the floor. If you’re doing the exercise correctly, you should feel a stretch in your quad muscles, but no pain in your knees.

The hamstrings are important muscles that help stabilize your knees during skiing. For this exercise, you need either a partner to hold your feet or an immovable object under which you can firmly lock your heels.

Place a thin, soft cushion on the floor. Kneel on the cushion. Have your partner hold your feet in place or lock your heels under an immovable object. Lean forward slightly to a count of five. Then return to an upright position. Repeat 10 times.

This exercise can be strenuous, so minimize your forward lean the first few times you perform it.

This exercise involves a continuous cycling motion. Lie down on your back on a mat on the floor. Begin with your right leg bent and your left leg straight. Lift both legs off the floor, while leaving approximately 12 inches between the floor and your left foot.

Place your hands behind your head, loosely touching your ears. By keeping your hands loose, you’ll prevent yourself from pulling your head and neck too far forward. Reach for your right knee with your left elbow, exhaling as you do so. Don’t let your upper back touch the floor.

Repeat the exercise on the opposite side of your body. Try 20 repetitions to start, and increase the number of reps over time. Breathe rhythmically as you perform this exercise, exhaling with each cross-over and inhaling as you return to center.

When it comes time to hit the slopes, start with a few easy warm-up runs. Remember to take regular breaks, stay hydrated, and eat healthy foods to stay energized. You should also stretch to help your muscles recover.