This 20-minute, no-equipment workout created by Victoria Brown, an Under Armour trainer and Certified Functional Strength Coach, is part of the Under Armour 21 Days to a Stronger Self challenge. It ...

Start in a push-up position but with your elbows on the ground, so your upper-body weight is on your forearms. As quickly as you can, move into a standard push-up position one arm at a time. Then ...

It’s normal to find the plank tough. The move demands strength in multiple muscle groups—to maintain the hold, keep your hips lifted but buttocks down, and a straight line from head to heels—all while ...