Fire hydrants

Start on all fours, with your hands underneath your shoulders and knees hip-width apart.
Engage your abdominal wall and lift your right knee sideways off the ground. Keep your knee bent and flex your foot.
Lift until your knee is level with your hips.
Lower your knee back down until it almost hits the floor and repeat.

Use your abs to keep your hips as level as possible.
Push away from the ground with your hands, so you don’t collapse in your shoulders.
Don’t crunch with your side abs.

Glutes