The American Physiological Society said the Iyengar method, created by B K S Iyengar, "is considered to be one of the more active forms of yoga".

Lead researcher and presenter Pamela E Schultz from Washington State University said: "It still has the meditative component, but it's been shown to have a physical output equivalent to a moderate-intensity exercise."

Dr Schultz and colleagues randomly assigned 10 breast cancer survivors to eight weeks of Iyengar yoga (two classes and a solo session at home per week) and nine to a wait-list control group. The women had an average age of 61, were about four years out from initial cancer diagnosis and were being treated with hormone therapy. None of the women had any prior experience with Iyengar yoga.

Psychosocial tests showed that the "demands of illness", reflecting the burden of hardship of being a breast cancer survivor, fell among the yoga participants.

"Psychosocial variables indicated improved quality of life with Iyengar yoga," Dr Schultz said.

Importantly, these improvements correlated with decreased activation of an important immune system protein called NF-kB, which is a marker of stress in the body.

"So it's possible that decreased activation of NF-kB indicates decreased stress in the body, which would be a positive thing. NF-kB can be activated by any type of stress in the body, like physical stress and mental stress," Dr Schultz said.

She plans to continue her research by looking at various immune system proteins to see if they too show changes for the better, "which would confirm immune and psychosocial benefits of Iyengar yoga".

source: news.com.au