It’s not running, and it’s not sex, either (which burns between 130-200 calories per hour).
After analyzing a bunch of different activities, including walking the dog (which burned just about at many calories as sex, by the way), they found out that boxing is one of the most effective ways to burn calories quickly. On average, people burned about 800 calories an hour, which is actually quite astonishing if you think about it.
Squash came in second place with about 748 calories per hour. If you’re like Producer David and have no idea what squash is, it’s pretty similar to racquetball, but with a smaller ball and bigger rackets.
Anyway. More info on what activities burn what calories, including a video of Chris Hemsworth’s boxing routine here. Swimming will burn 680 calories per hour, and running on a treadmill burns about 580, for example.