To up the muscle-building ante, try extending one arm in front of you when you're at the top of the push-up (which looks like a plank), suggests Jay Cardiello, fitness editor-at-large of Shape. Then, return your hand to the floor and lower into another push-up. Continue to alternate your arms with each rep, and see how many you can complete in 30 seconds. This variation challenges your balance and engages the muscles of your core, to keep your body stabilized.
The push-up isn't your only body-weight exercise that could use a makeover — click through for more simple ways to supercharge your routine. (Shape)