In this post, I’ll discuss some of the results of the study I described in my previous post. If you haven’t already done so, you should read that one before this.
To refresh your memory, Santaella and his colleagues studied the effects of bhastrika practice in elderly individuals (1). They tested several measures of respiratory function at the beginning of the study and again after four months of training. Those measures included forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and maximum expiratory and inspiratory pressures (PEmax, or MEP, and PImax, or MIP). Don’t worry about the abbreviations. Scientific research tends to read like acronym soup, but in general I’ll stick to the full names.
Breathe in as much as you can, then exhale out as much as possible. The amount of air you exhaled is your forced vital capacity. You’ll never empty all the air out of your lungs, so vital capacity doesn’t represent your lungs’ total capacity, but it’s a good measure of their useable capacity.
The air that’s left in the lungs after a complete exhalation is called the residual volume. Residual air is important. It helps to maintain a moist, carbon dioxide-rich atmosphere in the lungs and allows for continual gas exchange even after you’ve exhaled.
Vital capacity is a function of the size of your lungs, which is correlated with the size of your body, particularly your height. It’s also a function of your age. As you grow older, your lungs lose elasticity and your chest becomes stiffer. This leaves more air trapped in the lungs, increasing the residual volume, which leads to a gradual decline in vital capacity.
Now do the same exercise, breathing in and out as much as possible, but try to exhale as quickly as you can. The amount of air you exhale within the first second is called forced expiratory volume in one second, or FEV1. You may have done this test in your doctor’s office. FEV1 is an important measure of the health of your lungs. If you’re healthy, you should be able to empty out 80% or more of your vital capacity in the first second. If you can’t, because there’s some obstruction to the air flow, it could be a sign of asthma, chronic bronchitis or emphysema.
Maximum inspiratory and expiratory pressures are self-explanatory. They are measures of the maximum pressure you can generate while inhaling and exhaling through a mouthpiece. Both of them are indirect measures of the strength of your respiratory muscles.
The elderly lose both muscle mass and strength as they age, a process called sarcopenia. Exercise does a lot to mitigate sarcopenia, but some loss seems to be inevitable. Not surprisingly, as the strength of the respiratory musculature declines, maximum inspiratory and expiratory pressures also decline. That can be a serious problem for the elderly when conditions such as pneumonia place an extra load on the respiratory muscles. Since vital capacity and respiratory pressures decline with age, anything that improves them would be good news for the elderly.
So, did bhastrika practice help? The results were mixed. Maximum inspiratory and expiratory pressures improved significantly in the bhastrika group. Forced vital capacity and FEV1 increased slightly in the bhastrika group, but the difference was not statistically significant. The control group remained essentially unchanged, despite the fact that they were also practicing yoga (but without the bhastrika practice).
Research has generally shown that you can’t improve vital capacity with exercise. (On land at least. Swimming does increase vital capacity, probably because of the greater resistance to breathing that water provides.)
Some research suggests that yoga practice can improve vital capacity, but there are enough weaknesses in those studies that I’m not convinced. Most of the evidence comes from uncontrolled studies on students who were teenagers or young adults (2, 3). Women don’t reach full vital capacity until around age 20. For men, it’s around age 25. Without a control group, it’s hard to know whether those young people’s vital capacity would have increased regardless of yoga training. One large uncontrolled study (3) of college students did find increases across the board, regardless of age and gender. That’s suggestive of a training effect, but aside from the lack of a control group, there was also enough room for error in the testing procedures that those results aren’t as compelling as they could be.
I’ve only found one controlled study (4) showing a link between improved vital capacity and yoga. Unfortunately, there were major differences in the composition of the experimental and control groups in that study, and no details about the selection process, so again, I’m cautious about the results.
Other studies have found no correlation between yoga practice and vital capacity. It would be nice if there were better-designed studies to answer the question, especially for mature adults, but for the time being I’m not convinced that yoga does much to increase vital capacity. If it does, my guess is that the effect is small, unless you’re young. In that respect Santaella’s results weren’t surprising.
On the other hand, maximum inspiratory and expiratory pressures are a function of muscle strength. You can strengthen muscles, so you’d expect those measures to improve with training, and, in fact they did in this study. Overall, there hasn’t been much research on this topic. What little there is suggests that yoga practice can increase inspiratory and expiratory pressures (5), although in one of those studies (6) the difference was not statistically significant.
The bhastrika practice in this current study consisted of rounds of kapalabhati followed by breath retentions incorporating bandhas. I’ve written about kapalabhati before. It’s a strengthening exercise for the expiratory musculature, specifically the transversus abdominis as well as other abdominal muscles.
Inhalation retentions, particularly using jalandhara bandha, strengthen the muscles of inspiration. Jalandhara bandha is the “net-holding lock,” sometimes called chin lock. It requires you to hold the ribcage in a lifted position while bringing your chin towards your sternum. At some point, I’ll write about the physiological rationale for jalandhara bandha, but for now I’ll just point out that maintaining the position of the ribcage necessitates a strong contraction of the external intercostals along with the scalenes and the diaphragm, all of which are muscles of inspiration.
So, for the elderly individuals in this study, bhastrika practice seems to have strengthened their respiratory muscles. I should point out one caveat, though. The researchers in this study tested their subjects first to make sure they were healthy, and did not include any with evidence of cardiovascular disease in the study. Both kapalabhati and breath retentions can affect blood pressure. Because high blood pressure is common in the elderly, I wouldn’t recommend that senior citizens practice them unless they have a physician’s approval.
In the next post in this series, I’ll discuss the findings relating to heart rate variability.
1. Santaella DF, Devesa CRS, Rojo MR, et al. Yoga respiratory training improves respiratory function and cardiac sympathovagal balance in elderly subjects:
a randomised controlled trial. BMJ Open 2011;1:e000085. doi:10.1136/ bmjopen-2011-000085
2. Joshi LN, et al. Effect of short term ‘Pranayam’ practice on breathing rate and ventilatory functions of lung. Indian J Physiol Pharmacol. 1992;36(2):105-8.
3. Birkel DA & Edgren L. Hatha yoga: Improved vital capacity of college students. Alternative Therapies in Health and Medicine. 2000;6(6): 55-63.
4. Makwana K. Effect of short term yoga practice on ventilatory function tests. Indian J Physiol Pharmacol. 1988;32(3):202-8.
5. Madanmohan, et al. Effect of six weeks yoga training on weight loss following step test, respiratory pressures, handgrip strength and handgrip endurance in young healthy subjects. Indian J Physiol Pharmacol. 2008;52(2):164-70.
6. de Godoy DV, et al. Yoga versus aerobic activity: effects on spirometry results and maximal inspiratory pressure. J Bras Pneumol. 2006;32(2):130-5.
Image from Wikipedia Commons