This Plank-Push-Up Hybrid Is the Hardest No-Equipment Move in the Gym

Ready to work up a sweat? The plank push-up is the hardest no-equipment move in the gym. Here's how to do it correctly, according to a trainer.

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