Going upside down affects the body in the same way vigorous aerobic exercise does, by circulating blood down to the feet and up the back. (fivepillarsyoga.com)
This may be particularly important for those who are reluctant to take up other forms of vigorous aerobic exercise like running or cycling. (yogauonline.com)
And if you'd like to take that up a few notches, consider 30 to 60 minutes of more vigorous aerobic exercise four to six times a week. (mindbodygreen.com)