Deep twists can feel invigorating. However, avoid them if you are pregnant, or have a spinal fusion or injury.
To attempt this pose, begin seated in staff pose (dandasana), with your legs outstretched in front of you. Then, keeping the right leg straight, bend the left and try to sit on your left foot. To help balance, the toes of your left foot should be pointed right, and your bottom should sink into the arch or instep of your left foot. If this is uncomfortable, try sitting on a cushion or place your left foot under your right upper thigh. Anyone with knee replacements or injuries should keep the left leg straight.
Once you find your seated balance, cross the right leg over as far as possible. The sole of the foot should be flat on the ground outside your left knee or thigh. The right knee points upward.
Maintaining your balance, inhale and lengthen the spine. Exhale and twist your torso as far as you can to the right. If it's comfortable for you, look over your right shoulder.
Next, to deepen the twist, place the left bent elbow outside the right knee. The fingers of your left hand should point to the sky. Hold for close to a minute and then repeat on the other side.
As mentioned in my book, "From the Boxing Ring to the Ashram: Wisdom for Mind, Body and Spirit," this is an excellent pose for people with piriformis syndrome. As Dr. Loren Fishman explains in my book, piriformis syndrome is caused by muscles pressing against nerves. This deep twist helps to stretch out the compressed area.