The hardest jumping jack you will ever do involves a resistance band and *all* of your muscles

I tried resistance band jumping jacks with celebrity trainer Don-A-Matrix, and I'm still sore days later. Here's how to do them yourself for a strength + cardio burst.

alt
Photo: Getty Images/gradyreese

Adult Ballet is on the Rise—And Yes, You Should Totally Try it

Here's what to know before your first class.