In a recent study published this week in the journal "Annals of Internal Medicine" by the American College of Physicians, researchers found yoga classes designed specifically for back pain can be as safe and effective as physical therapy in easing pain. The authors came to the conclusion after studying 320 adults with chronic lower back pain, who were assigned to yoga and physical therapy classes for 12 weeks.

Both groups showed almost the same amount of improvement over a period of time. Apart from the yoga and the physical therapy group, there was a third one which was called the education group where participants were tutored on back pain by being given self-help books and mailed newsletters.

"The improvements in pain and activity limitation in the yoga and physical therapy groups were also found at 1 year and were similar to each other. Yoga did not perform better than education in terms of improvement in pain and activity limitation at 3 months. However, participants in both the yoga and physical therapy groups were less likely to use pain medications at 3 months compared with the education group," the study said.

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The participants were of diverse racial backgrounds and mostly from low-income families. Several of them had pre-existing medical conditions and researchers said this factor was important as chronic back pain — which affects about 10 percent of U.S. adults — has a greater impact on minorities and people of lower socio-economic status.

Till now, most studies on yoga for back pain were confined to studying only white and middle-class people, according to lead author Dr. Robert Saper, director of integrative medicine at Boston University School of Medicine, as reported by Time. "We feel that it was important to test whether the yoga would be received well by an underserved population as well as being effective," he said.

Here are five yoga poses to help you get relief from severe back ache.

1. Two-Knee Twist

Lie on your back, bend your knees into your chest and bring your arms out to form a "T." As you exhale, lower down your knees to the ground on the right. Keep both the shoulders pressed down firmly. If you lift your left shoulder, lower your knees further away from the right arm. Hold for around two minutes each side and repeat the pose.

2. Sphinx

Lie on your stomach and prop yourself up on your forearms. Slowly, align your elbows directly under your shoulders. Your palms and top of the feet should be firmly pressed against the ground. Breathe as you stay in this position for one to three minutes. You will start feeling sensations in your lower back. This allows blood flow into the lower back for healing.

3. Pigeon

Lift your right knee and bring it behind your right wrist and keep your lower leg diagonal towards your left hip. Square off your hip towards the ground and bend forward. Widen your elbows and place one hand on top of each other in a way your hands act as a pillow for your forehead. Stay in that position for two to three minutes and repeat the same position with the left leg.

4. Thread the Needle

Lie on your back and bend both the knees with feet flat on the ground. Bend your right knee like a figure "4" with the outer left ankle to the right thigh. Lift your left leg into the air and bring the left calf parallel to the ground. Put your right hand in the space between the opening of the legs and interlace your hands behind your left thigh. Stay in this pose for two to three minutes.

5. Legs Up the Wall

Lie down and lift your feet up the wall. Keep your hands straight on either side of the body. This pose will help relaxing muscles of your lower back and it will drain stagnant fluid from the feet and ankles. Stay in this pose for five to 10 minutes. Practice this pose after a challenging workout and always after traveling by plane.