Yoga improves respiratory function

Apr 6 2006

Young and healthy Thais who participated in just 18 short yoga sessions showed significant improvements on six of seven measures of respiratory function, according to research from Khon Kaen University.

"This research suggests that short-term yoga exercise improves respiratory breathing capacity by increasing chest wall expansion and forced expiratory lung volumes," said lead researcher Raoyrin Chanavirut. "These findings may benefit people suffering from illnesses that affect breathing, including asthma." The researchers chose five Hatha Yoga positions designed to improve chest wall function, including the cat, tree and camel positions.

Fifty eight healthy volunteers, all around 20 years old, participated in the six-week study. Half of the volunteers did five positions of Hatha Yoga during 20-minute sessions, three times a week. The control group did not do the exercise, but continued their usual lifestyle, and did not smoke or drink, Chanavirut said.

The researchers obtained base line lung expansion and lung volume measures on the 58 volunteers before the experiment began and took final measurements after the experiment ended. They used a tape measure to determine lung expansion capacity, measuring the

• upper chest (sternum)
• middle chest (rib 5)
• lower chest (rib 8)

"Chest wall expansion allows individuals to get more air to the base of the lung," Chanavirut explained. Greater expansion of the chest wall provides more oxygen with each breath and requires less effort to breathe, she said.

The researchers used a spirometer to measure

• tidal volume
• forced expiratory volume (FEV1)
• forced expiratory volume (FEV25-75%)
• forced vital capacity (FVC)

Improvement on six measures

FEV1 is the amount of air a person can forcibly blow out in one second, and is one of the most important indexes of lung function, Chanavirut said. FEV25-75% is the average speed of the air coming out of the lung during the middle portion of the expiration. FVC is the total amount of air an individual can forcibly blow out after full inhalation.

The researchers found that the volunteers who did yoga over the six-week period significantly improved their chest wall expansion at all three measurement points, and also showed significantly better forced expiratory volume (FEV1, FEV25-75%,) and forced vital capacity (FVC). The yoga sessions did not affect tidal volume, that is, the amount of air that passes in and out of the lungs in an ordinary breath.

It is not yet known whether the improvement in FEV occurred because the expiratory muscles became stronger, there is less airway obstruction, or both, Chanavirut said. The improvement in FVC may have been the result of a

• strengthened inspiratory muscle
• better chest expansion
• stronger expiratory muscle
• less airway obstruction.

The authors concluded that even short-term yoga practice improves breathing capacity by increasing chest wall expansion capacity and forced expiratory lung volumes. The study could help people with asthma, those suffering neuromuscular conditions such as myasthenia gravis, and individuals who have undergone thoracic and abdominal surgery, Chanavirut said.