7. Plank Jacks
A plank jack is basically just holding a plank position and then jumping your feet from narrow to wide. I recommend a full pushup plank position, but a forearm plank works as well.
Begin in your desired plank position. Jump your feet out wide, then quickly bounce back to the starting position, keeping your core stable. Repeat for the prescribed time.
8. Bicycle Crunches
Bicycle crunches are a great core exercise that adds cross-body core activation to your bodyweight training calorie-burn circuit.
Start by lying on your back with your hands behind your head, your knees bent, and your feet in the air. Bring your left elbow to your right knee while straightening out your left leg. Switch sides, bringing your right elbow to your left knee while straightening out your right leg. Repeat for the prescribed time, alternating sides on each repetition.