The upward plank is a bit like an upside-down press-up. It can be an excellent stretch for the shoulders and chest muscles, particularly after a long day of carrying a heavy pack. Here are two variations:

Gentle upward plan (pictured above)

1. Start sitting on the floor with your feet hip-width apart. Feet flat on the floor and just forward of your hips.
2. Put your hands on the floor behind you, palms down with fingers pointing forward. If this is uncomfortable, you can try turning your fingers out.
3. Press down through your hands, lift your chest forward and up. Let your shoulders come down away from your ears and slightly back. Relax your shoulders. Do not pinch your shoulders back.
4. Hold for a few breaths, rest and repeat.

Intense upward plank

1. For a more intense stretch, keep the action in your hands, arms, chest and shoulders but now try lifting your hips up.
2. Press your feet into the floor. When your hips come up, your ankles should be directly under your knees and hands directly under shoulders. You may have to bring your hips down to move your feet forward. (If you feel pain in your shoulders, return to the gentle pose.)
3. Hold for a few breaths, rest and repeat.