The Cardio Effects of Yoga

Yoga is popular these days. People who practice yoga on a regular basis claim that it encourages deeper breathing and relaxation, improves muscle tone and, in general, just makes them feel better. Data from many studies have demonstrated the positive effects of yoga on mental and physical health. The authors of a study published in BMC Complementary and Alternative Medicine wanted to know what happens to the heart rate and metabolism of a person practicing yoga, and whether practicing yoga meets the recommended level of physical activity required for improving or maintaining cardiovascular fitness. The study compared the heart rates of 18 women during a yoga session, with their heart rates while walking on a treadmill. Results from the study showed that heart rates fluctuated during a yoga session, so that some yoga components reached recommended levels, while others did not.

Each participant performed a specific routine inside an air-tight room known as a respiratory chamber, where rates of oxygen consumption and carbon dioxide production can be measured. Each participant wore a heart monitor. First, they sat quietly or read for 30 minutes, in order to obtain a resting metabolic rate. Each participant then followed a 56-minute beginner-level yoga DVD, which began with 28 minutes of sun salutation poses, followed by 20 minutes of standing poses, and, finally, 8 minutes of sitting and lying poses, for relaxation. When they finished the yoga session, subjects walked on a treadmill at 3.2 kpm (2 mph) and 4.8 kph (3 mph), for 10 minutes each. To determine the reliability of their measurements, seven participants returned at another time to repeat the same test protocol.

The authors found that overall the physical activity expended during a yoga session is similar to walking on a treadmill at 3.2 kph, and does not meet the recommended requirement for improving health and fitness. A yoga session combines standing, sitting, and lying down, so that the metabolic costs of the activity vary throughout the session. They found that values for sun salutation poses were substantially higher than those for treadmill walking at 3.2 kph, and similar to recommended values for moderate levels of exercise intensity. The authors concluded that a session that includes at least 10 minutes of sun salutation postures may provide some cardio-respiratory improvement for a sedentary person, but probably not for someone who exercises on a regular basis. The relatively low level of physical activity associated with yoga may still be enough to provide a metabolic boost, even if it appears not to meet certain standards of cardio-respiratory fitness. For example, even a small amount of physical activity has been shown to reduce insulin resistance in patients with Type II diabetes.

Walking on a treadmill provides an excellent cardiovascular workout. Doing yoga clearly benefits body, mind, and spirit, but researchers are just not sure how. The results of this study demonstrate that physical activity levels cannot adequately explain the well documented benefits of yoga. There is more to it than that. People who practice yoga on a regular basis claim that it increases flexibility, encourages deeper breathing and relaxation, and can lead to an increased sense of well being. Perhaps the benefits of yoga cannot be explained in terms of physical activity levels or metabolic costs, and scientific measurements may never bring a true understanding. Besides, anyone faithful to the practice of yoga requires no scientific validation. They know it works, even if they cannot fully explain why.

Resource

Hagins, M., Moore, W., Rundle, A.

Does practicing hatha yoga satisfy recommendations for intensity of physical activity which improves and maintains health and cardiovascular fitness?

http://www.biomedcentral.com/1472-6882/7/40