Menstrual cramps can bring pain to your stomach, lower back, pelvis, and upper legs. But some good stretches and moderate exercise can help. Try cobra, a classic yoga pose. Lie on your stomach, legs and feet together. Place your hands under your shoulders and lift your head and shoulders, straightening your arms. Breathe, and let your stomach expand on the inhale and soften on the exhale. Hold the pose for 30 to 60 seconds. Relax and repeat.