Look, I’m gonna be straight with you – those online calculators that tell you exactly how many jumping jacks you need to burn 500 calories? They’re basically making educated guesses about your body.

"Hearst Magazines and Yahoo may earn commission or revenue on some items through these links." YOU MIGHT THINK back to your childhood gym class and remember learning the basics of physical fitness, ...

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Planks and jumping jacks are perfectly fine workout moves. But if you combine the two together, you can actually get an even better total-body workout. Meet: the plank jack! How To Do Plank Jacks For ...

TL;DR Your personal metabolism can make the difference between needing 1,000 or 2,000 jumping jacks to burn 500 calories The surface you jump on and how you move can change calorie burn by up to 35% ...