The one exercise that’s better for a strong core than a plank

This stability ball exercise is even better for a strong core than a plank. Here's exactly how to do it properly, according to a trainer.

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Photo: <a href="http://www.stocksy.com" target="_blank" rel="noopener noreferrer">Stocksy</a>/Javier Díez

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

Here's what to know before your first class.