Plank up-downs are guaranteed to tighten and strengthen your underarms.
Konforti's form tip:
- Start in a push-up position.
- Lower your right elbow to the ground, then your left, so you're in an elbow plank.
- Place your right hand underneath your shoulder and press up as you do the same with your left hand, returning to a push-up position. Repeat and alternate which arm you start the motion with.
- Complete this exercise for 45 seconds.