If available, you can use a cable machine for this exercise.
Alternatively, fixate a resistance band to a solid object at knee height.
Lie on your back with your knees bent and your feet flat atop the round side of a BOSU.
Reach your arms up above your head whilst holding one handle in each hand.
Engage your deep abdominal muscles.
Inhale.
Exhale as you lift your buttocks from the floor into a bridge position by engaging your glutes whilst simultaneously pulling your arms straight down to your sides against the resistance.
Take care to ensure your you are in a straight line from your knees to your shoulders and that your hips remain level as you extend one knee, keeping your thighs parallel.
Hold this position, then return your foot to the BOSU and repeat with your other leg.
Control your buttocks back to the floor and slowly raise your arms back to the start position.
Repeat.