The vital capacity of our lungs is vital to our health. Vital capacity (VC) is not the total capacity of our lungs, but rather the total amount of air we can inhale once we have exhaled fully. Generally, more is better, and our yoga practice can help expand and maintain our VC.
Vital capacity varies from person to person and can be correlated with a person’s height, gender, aerobic conditioning, overall health, socioeconomic status and ethnicity.(1) Taller people tend to have larger lungs and a larger total lung capacity. Higher percentage body fat (adiposity) is inversely associated with changes in lung volumes. (2) Men, on average, have 12% greater lung capacity than women of the same height.(3)
Lung function increases as we grow up, to a maximum around the age of 20 for women and 25 for men. It then stays pretty level until 35, after which it starts to decline.(1) To be more specific, the total lung capacity actually remains fairly constant as we age, perhaps even increasing slightly, but our residual volume, the amount of air in our lungs after a full exhalation, increases significantly, which decreases our vital capacity.(1) (These terms are illustrated in figure 1 below.)
FIGURE 1: Lung volumes and capacities.(4)
As we get older, what is important is not how much we can breathe in but how much we can breathe out!
As we move into our 50s and beyond, our rib cage tends to become permanently elevated (see Are you a Belly Breather?), our ribs more horizontal, and our costal cartilage stiffer. In effect, we get stuck in the “inhalation” position, unable to lower the ribs during exhalation as much as we once could. Also, as we get older, we see a decrease in the natural elasticity that helps the diaphragm passively reduce the chest volume.
When these tissues become stiffer, exhalation is neither as natural nor as passive as before; more work is needed to fully exhale. Additionally, more work is needed to inhale, in order to overcome the stiffness. Balancing this is a decrease in the lungs’ elasticity, which makes it easier for them to fill with each inhalation, but reduces their recoil on exhalation.(4) With a permanently elevated rib cage, exhalation takes more work; we have to rely upon the diaphragm rather than the elasticity of the rib cage to exhale. Unfortunately, our diaphragm also tends to weaken as we get older.(1) Table 1 shows how vital capacity decreases as we grow older.
TABLE 1: Variations in Vital Capacity by age and gender (in ml). In parentheses is shown the range of variation for one standard deviation in both ml and percentage.(5)
As an experiment, place one hand on the sides of your lower ribs and the other on your sternum and notice how a deep inhalation moves the lower ribs to the side and raises the sternum (see figure 2 below). This expansion of the rib cage creates more volume in the lungs, allowing a deeper inhalation. This extra volume is still available when we are older, but now we may no longer be able to reverse the process fully. So, focus now on the exhalation. With the hands on the lower ribs and the sternum, take a deep breath in, and then slowly exhale, forcing the sternum down and the lower ribs in. Maximize those movements as much as you can.
FIGURE 2: The older we get, the more we need to work to enhance our exhalations. With one hand on the lower ribs and the other on the sternum, take a deep inhalation and notice the movements. Keeping the hands there, exhale and try to reverse the movements as much as possible: Draw the sternum down and the ribs in fully.
As we grow older, the challenge is not to increase the amount we inhale but to increase the amount we can exhale! Practicing reducing your rib cage size with each exhale may help to maintain the natural elasticity between the ribs as long as possible.(6) This is something we can work on during yoga: At the beginning of your practice, try a few deep breaths, focusing on completely emptying your lungs, drawing your lower ribs in as much as you can. You do not need to overdo this: a minute or two should be sufficient. If you feel dizzy or lightheaded, stop. If you have breathing challenges, check with your health care provider before trying these exercises.
Slowing the breath is better than deepening the breath.
Sometimes, we don’t need to breathe more (or deeper), just slower. We are all different, and these differences can affect the way we use our breath while in meditation or while doing our physical yoga practice. Lengthening the breath so that we breathe six times a minute improves our heart rate variability (which is an indication of the health of our vagus nerve), turns off the “fight or flight” response (the sympathetic nervous system), and stimulates the “rest and digest” response (the parasympathetic nervous system).(7) But this slower breath does not necessarily mean that the breath must be that much deeper!
Due to a variety of complex chemical cascades, slow, shallow breathing may be much healthier for most of us than deep breathing. One good way to ensure the breath is slow but not necessarily deep is to breathe through the nose. This is done in most forms of pranayama practice and in ujjayi breathing, but one particular form of pranayama has been specifically studied. It is called alternate nostril breathing, and involves inhaling through the left nostril, exhaling through the right, then switching and breathing in through the right and out through left. Also called nadi shodhana, nadisudhi pranayama or anuloma viloma, this practice has been shown to reduce heart rate, breathing rate, and diastolic blood pressure.(8)
Next time you are feeling anxious or a bit on edge, try breathing slowly through the nose, not necessarily deeper, and see whether it works for you.
This article is excerpted from Your Spine, Your Yoga—Developing stability and mobility for your spine by Bernie Clark.
1. See G. Sharma and J. Goodwin, “Effect of Aging on Respiratory System Physiology and Immunology,” Clinical Interventions in Aging 1.3 (2006): 253–60.
2. See Tim J. T. Sutherland, et. al., "The relationship between body fat and respiratory function in young adults" in European Respiratory Journal 2016 48: 734-747.
3. See Francois Bellemare, Alphonse Jeanneret, and Jacques Couture, “Sex Differences in Thoracic Dimensions and Configuration,” American Journal of Respiratory and Critical Care Medicine 168.3 (2003): 305–12.
4. Neumann, Kinesiology of the Musculoskeletal System, 3rd ed., 456.
5. The study was done on 1,965 Serbian men and 2,539 women between 2001 and 2006; see Pavlica et al., “Correlation of Vital Lung Capacity.”
6. I wish I could cite a study that proves this exercise works to maintain our vital capacity as we get older, but alas, I could find no such research. The value of this exercise will have to remain a conjecture for now. But I suggest you try it to see whether you find it benefits you.
7. See Luciano Bernardi et al., “Effect of Rosary Prayer and Yoga Mantras on Autonomic Cardiovascular Rhythms: Comparative Study” British Medical Journal 323 (2001): 1446–9. For a summary of research showing that slow breathing leads to personal, social, and global health benefits, see Laborde et al., “Heart Rate Variability.”
8. See K. Upadhyay Dhungel, V. Malhotra, D. Sarkar, and R. Prajapati, “Effect of Alternate Nostril Breathing Exercise on Cardiorespiratory Functions,” Nepal Medical College Journal 10.1 (2008): 25–7.