Mountain climbers work your entire body, and pulling your knees in while maintaining a plank position will strengthen your whole core, obliques including. For even more oblique work, consider adding in a twisting modification.
- Start in a plank with your shoulders directly over your wrists. Keep your back flat, your hips down, and your spine neutral.
- Engage your core, and draw your right knee in toward your chest. Hold this position for one second, then return the right foot to the starting position.
- Repeat with the left leg, driving your left knee toward your chest, holding for one second, and then returning to the starting position.
- Continue alternating sides without speeding up the pace.
