Asana practice as cardio?

Think “cardio” and the type of activity which comes to mind is likely to be running, swimming, or cycling – intense repetitive activity that is usually sustained for 20 minutes or more. Asana practice, that is the practice of yoga postures, is not usually associated with the term. However, asana practice, particularly of the Ashtanga or Vinyasa flow variety, can also constitute cardiovascular activity.
Cardiovascular activities are those characterised by a slightly elevated heart rate which allow you to sustain the activity over a prolonged period. During this period, the exertion of muscles requires additional oxygen, and the heart rate increases in order to cater to this demand for additional oxygenated blood. Over time, cardiovascular activities increase cardiovascular health. This means that the heart is able to supply more oxygenated blood (cardiac output) to the body with less effort (i.e. at a lower heart rate). By way of an illustration, whereas your heart rate may increase to 150 beats/minute the first time you run 10 km, running 10 km regularly is likely to increase your cardiovascular health and the heart may get more efficient such that it only increases to 110 beats/minute when you run 10 km.
As highlighted above, the first requirement for an activity to count as cardio is that there must be an increase in heart rate. This may disqualify static asana practice such as traditional Hatha yoga or yin yoga as the emphasis on holding the posture for a long period of time may not elevate the heart rate sufficiently. Ashtanga or Vinyasa flow asana practice on the other hand are more likely to elevate heart rate – perform Surya Namaskar 10 times with jumps forward from downward dog and back into chautranga, and you are bound to find that your heart rate is increased. A 60 minute Vinyasa flow practice incorporating asanas which target larger muscle groups such as the quadriceps and hamstrings (think fast transitions from warrior poses to standing balancing poses) is also likely to elevate the heart rate as the larger muscles will require more oxygenated blood. Practice this in a heated room, and the heart rate is likely to elevate even further.
Ultimately, whether an activity counts as cardio would depend on an individual’s level of fitness. As an individual gets fitter and the heart gets conditioned to supplying more oxygenated blood more efficiently, the intensity of the activity would have to be increased in order for the same elevated heart rate to be achieved. For yogis, this could mean incorporating more challenging asanas into a Vinyasa flow (think transiting from inversions to arm balances and jumping back into chaturanga). The wonderful thing about asana practice is that there is never an end to learning – we can always strive towards better alignment or a smoother transition.
Go get sweaty!

200hr YTT Vinyasa Flow