Setup
Position upper back on a plyobox with chin tucked slightly, feet about shoulder width apart and knees bent with glutes resting on the floor, engage your core.
Movement
Engage your glutes and drive your hips up pushing through your heels and keeping your back straight and pivoting through your upper back, when your shoulders, hips and knees are in a straight line stop the movement and pause the amount of seconds as prescribed at the top. Maintain your shins in a vertical position to bias the glutes. return to the start
Tip
Keep your chin tucked like you are holding an orange between your chin and sternum.
Do not flare your ribs outward
Feet far apart will bias the hamstrings, closer together will bias the quads
Squeeze the glutes hard at the top of the movement as you pause
Do not let your knees cave in
Maintain a neutral spine position, do not overarch your low back