Planks

Chieflrg

100 calories per 5 minutes. Source: http://www.flaviliciousfitness.com/blog/2013/01/29/best-ab-exercise/

You will want to scroll down to the comments where people say that they don't believe one can burn 100 calories in 5 minutes. :ohwell:

I will call BS to any site that states this. I run 5k in a lil over 20 minutes at 220lbs and I don't burn at that rate, no way.