The plank jack is a dynamic core exercise that combines the plank position with a jumping jack motion. This exercise targets the core, shoulders, and legs, improving strength, stability, and cardiovascular fitness.

1. Start in a plank position with your hands directly under your shoulders and your body in a straight line.
2. Jump your feet out to the sides, wider than hip-width apart.
3. Jump your feet back together to the starting position.
4. Continue the jumping motion while maintaining a strong plank position.