Our practice shifts from heat-building flow (countering winter stagnation) to gradual twists to wring us out for spring.
Twist conservatively if you have spinal issues (bulging discs, pinched nerves) and evaluate how you feel later that day/the next day to determine how "far" is safe for your body.
Donna Farhi writes that forcing the body's bones/muscles into a twist is "one of the most common causes" of injury in yoga practitioners. Turn no further than your organs permit and let "the muscles and bones support and guide the intention and initiation of the soft inner organs" (159).
Farhi, Donna. Yoga Mind, Body & Spirit (A Return to Wholeness). New York: Henry Holt and Company, 2000. Print.