The Jackknife is an excellent conditioning exercise. In many ways it’s a double Mountain Climber, although it’s difficult to match the Mountain Climber’s speed.
Online Personal Training Video: Jackknife
How To Do It
1. Begin in the pushup position.
2. “Jump” both legs forward to your chest to the tucked position, as if preparing for a squat thrust.
3. “Shoot” your legs back to the pushup position. Repeat.
Online Personal Trainer Tips
1. As with other primarily cardio exercises, breathe normally.
2. Keep your eyes on a spot a foot or so in front of you on the floor. To avoid neck injury, do not stare straight forward.
