A strong, stable core is the foundation you need to not only prevent injury but move freely and strongly in every workout. Add the 30-day plank challenge to your training plan as a supplement and you'll see noticeable changes in just a month's time.

You won't find any "hold a plank for 30 seconds" business here. We're talking moves that challenge and sculpt your core like never before.

Each day, you get a plank workout move that builds upon the last, leading to new challenges at the end of each week.

How it works: You'll learn a new twist on the classic plank daily. Plus, at the end of each week, you'll put those moves together for a plank workout flow that works your strength and endurance.

Add this to your existing training plan for triathlon, cycling, running or general fitness.