This exercise provided courtesy of Billy Polson, founder and co-owner of DIAKADI Body training gym, voted best personal training gym in San Francisco by CitySearch in 2006.
Football players train using this exercise, which gets your heart pumping as you work your quads and hip flexors. Jog forward and back for two minutes, lifting your knees as high as you can, as fast as you can, on each step.
Stand in a room with at least 40 feet of open floor in a straight line, such as an aerobics room, basketball court, or even a sidewalk, with as much space as possible in front of you.
- From the starting position, begin a knees-high jog forward down the floor. Bring alternating knees rapidly toward your chest as you push off with your feet, such that between knee lifts there is a moment when you are completely off the floor. Keep your chest lifted as you jog, and pump your arms in a natural rhythm. The more quickly you lift your knees the harder this exercise will be, but think of this as the speed of the knee lifts, not as going faster across the ground (see Photos 2 to 4).
- When you reach the end of the room, or in one minute of forward jogging (whichever comes first), reverse direction and jog backwards, keeping your knees just as high as you did on your forward trip. Be careful not to go backwards too quickly, or you risk falling. Continue traveling up and down the room, keeping up the speed and height of the knee lifts, for a total of two minutes (see Photos 5 and 6).