Are there restrictions for doing pranayama?
 
For most people, pranayama is safe and can improve their health. But if you have any medical conditions that are a concern, such as a history of lung or circulatory problems, please be sure to check with your doctor. Although you're usually not working up a sweat with breath work, it's still a form of exercise and can have a dramatic effect on the body. So treat it like any other activity, which means you should get medical clearance if you have an inkling that it might not be safe for you. If you have a history of breathing or circulatory conditions, it's safest to avoid pranayama practices that involve holding the breath, either in or out, as well as those that involve fast or vigorous breathing.  
 
Once you have the green light, here's a breathing exercise I recommend:  
Start slowly by lying in Relaxation Pose, head and neck supported on a folded blanked, with a roll under your knees and one under your ankles. Cover your eyes with a soft cloth and your body with a blanket to stay warm. Begin by watching your breath for 20 breaths. Then gradually begin to increase the length of each inhalation and exhalation so they grow longer and longer. Keep the breath soft and exactly even and never strain. Try this elongated breath for 10 breaths, gradually building up to 20. This Centering Breath will calm and quiet you. Practice every day, and let the length of the breath increase naturally. When you are done, lie quietly for five minutes, then roll to your side and use your arms to help you sit up slowly. 

Judith Hanson Lasater, Ph.D, and PT, has taught yoga since 1971 and is the author of six books including the latest, “A Year of Living Your Yoga.’’