The above chart explains various exercise zones vis-à-vis its intensity (in terms of heart beat rate). In order to understand the vital role of Shavasan in Yogic practice we will just focus on two zones – Aerobic & Anaerobic.

Long distance running, sports like badminton, tennis and few yogic postures are examples of aerobic exercises. On the other hand, anaerobic exercises are high-intensity brief exercise like one hundred meters sprint.

The intensity and nature of aerobic exercise are such that all the oxygen required for performing them can be breathed in essentially during the exercise itself. That is not possible with more intense exercise performed for a short time. In the case of these exercises, called anaerobic, the body incurs an ‘Oxygen Debt’ which is ‘paid back’ by breathing in extra oxygen after the exercise.

Although Yogic postures are low-intensity exercises, the changes in thoracic and abdominal pressure and fluctuations in oxygen supply (due to breath holding) are comparable to those produced by rather high-intensity non-yogic exercises, typically of an anaerobic nature. Hence during yogic postures also, body incurs ‘Oxygen Debt’ and which can be paid off by relaxing the body by way of Shavasan.

Always remember, what makes Yogic Exercise different from other forms of exercise, is the sequence of yogic postures is so designed that at the end of the session a person is relaxed rather than tired (which is a case with other forms of exercise).