Heart Rate Zones | Everything You Need To Know About How Heart Rate Zones Work (And How To Become An Exercise Physiology Ninja). Read more: http://www.bengreenfieldfitness.com/2013/03/how-heart-rate-zones-work/#ixzz2vtYSEPEu
Stand with your feet more than hip-width apart, toes turned out slightly, and hold a heavy dumbbell vertically in front of your chest (a). Bend your knees to lower your body to the floor as far as possible (b). Push through your heels to stand, then rise up as high as you can onto your toes. Return to start. That's one rep. Do 15 to 20.