Main focus area: Abs.
Why do this?
Cross crunches resemble the air bike exercise, only cross crunches focus more on strength. These help to develop a good general abdominal strength. The complex motion activates most abdominal muscles in an alternating fashion. This motion is closest to the abdominal motion during running. Therefore, this exercise is a great support to make running more effective.
How to do this?
- Lie on your back and bring your knees up to a 60 degree angle, keep your feet flat on the floor.
- Place your hands on either side of your head (over your ears).
- Curl up raising your right elbow and your left knee so that they touch over your chest.
- Return to the starting position and repeat with alternate arms and legs.
How to vary?
Increase difficulty: Hold the posture for a moment when you left elbow meets your right knee or vice versa. This destroys momentum and you need to squeeze your abs a bit longer at their peak tension.
Decrease difficulty: Leave the feet on the ground.