Posts Tagged ‘science_and_yoga’
In a 2010 survey paper, researchers found that at least when it comes to VO2 max, Yoga asanas are inferior1 to physical exercises2. VO2 max, maximum oxygen consumption, is a standard measure for the physical fitness of an individual. But in most of the other health outcomes covered in the “meta-analysis”, yoga was just as good if not better than exercise.
Below is a comprehensive table from that 2010 survey paper3 comparing the Health Benefits of Yoga and Exercise (see here for pdf version of the table below):
Here is a brief description of the studies the researchers reviewed:
Table 2 provides a summary of the studies comparing yoga and exercise by outcomes measured. Nearly half of the studies have been conducted on healthy populations, and yoga interventions have yielded positive results in both healthy and diseased populations. Nearly every study utilized a yoga intervention that combined physical asanas (standing, seated, or inverted) and restorative or relaxation poses. Seven of the 12 studies also incorporated meditation and/or breath work. Three studies did not specify the type of yoga intervention used. The remaining studies utilized Hatha yoga (N=4), Iyengar yoga (N=3), and Integrated yoga (N=2). While five of the studies provided specific sequences of yoga poses used in the intervention, the remainder offered few details.
… Most of the studies involved some form of aerobic exercise: walking, running, dancing, or stationary bicycling, plus some form of stretching. Two studies compared yoga with gentle, nonaerobic exercises and stretching.
(1) The researchers found that “… yoga interventions appeared to be equal or superior to exercise in nearly every outcome measured except those involving physical fitness. The studies comparing the effects of yoga and exercise seem to indicate that, in both healthy and diseased populations, yoga may be as effective as or better than exercise at improving a variety of health-related outcome measures.”
(2) Granted, none of the subjects performed Rodney Yee’s extreme example of 108 sun salutations in a row!
(3) The health benefits of yoga and exercise: a review of comparison studies, pdf version here.
One of the enduring myths in yoga circles is the notion that the proper execution of breathing techniques (Kapalbahti and other forms of Pranayama), can flood the body and brain with revitalizing amounts of oxygen. As an example, Indian TV Guru Baba Ramdev recently made such a claim in a BBC program (jump to minute 2:20 below):
To understand why such claims are misplaced1, consider the following summary from William Broad:
… The atmosphere of our planet is 21% oxygen, That’s a lot. In comparison, the levels of carbon dioxide are 500 times smaller. The human body exploits this ocean by means of hemoglobin — the remarkable protein inside our red blood cells that soaks up oxygen like a sponge and carries it from the lungs to the tissues. Typically, the refreshed hemoglobin of a resting person is nearly saturated with oxygen, holding virtually as much as it possibly can. The usual figure for the level of absorption is 97%.
For yoga the glut of oxygen in the air and the saturation of hemoglobin in the lungs mean that fast or slow breathing does little to change the levels that enter the bloodstream — as Gune found at his ashram and as I found in the University of Wisconsin. The vital gas is available in large quantities no matter what.
The body’s consumption of oxygen does go up and down. But science demonstrates that it does so in response to changes in muscle activity, metabolism, and heart rate — not breathing styles. As we saw in the last chapter, cardiovascular fitness can raise peak oxygen consumption2.
(1) When the lungs are diseased or impaired, “slow breathing may aid oxygenation”. See here.
(2) A 2010 paper (The health benefits of yoga and exercise: a review of comparison studies, pdf version here), found that “… yoga interventions appeared to be equal or superior to exercise in nearly every outcome measured except those involving physical fitness. The studies comparing the effects of yoga and exercise seem to indicate that, in both healthy and
diseased populations, yoga may be as effective as or better than exercise at improving a variety of health-related