The ‘C-Crunch Rock’ Instantly Sets Fire to Your Core With a Twist

The 'C-Crunch Rock' fires up your obliques in seconds. Here's how to do it, according to Keoni Hudoba, creator of COREntine.

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