This video presents the second level of the Copenhagen plank, which utilizes a straight leg for a longer lever and increased challenge. To set up, place your foot and ankle on an elevated surface, aiming to align your foot with your knee, hip, and the top of your head. Lift up to form a straight line, push through the glute, and hold the position. The lower leg can be in a comfortable stance. You can increase the difficulty by having someone place a small weight on your ankle. This longer lever creates more stress, which can be beneficial for strengthening the muscles and tendons around the knee if you can handle it, but you should work your way up to it. Hold the pose for anywhere from 30 to 60 seconds and perform about two or three sets, which can easily be incorporated as an accessory exercise to a main lift.