Trunk Flexion

A good exercise for developing muscular strength for the internal / external oblique's, and deeper stabilization (quadratus lumborum) muscles.

Lie on your side, positioning yourself so that your belly button is on the center line of the Bosu. Keep the lower leg straight, inline with your spine, resting the side of your foot on the floor.

Your upper leg should be placed either slightly forward on the floor, to aid balance; or resting on the lower leg / in the air to increase difficulty.

Support the weight of your head with your lower hand, or rest your hand on the floor to aid stability, whilst the elbow of the top arm faces upwards. Begin the exercise with your side resting relaxed along the Bosu.

Exhale and contract the top oblique's, lifting to a straight spine position, aiming to prevent any twisting during the lift whilst avoiding bending the neck.

Pause in the upright position for a few seconds, then inhale deeply back to the start position before repeating. The complete exercise is best performed in a slow rhythmical manner, concentrating on using the top oblique / internal muscles.

Beginner should aim for 4 - 8 repetitions each side.

Intermediates perform 6 - 10 repetitions each side repeated twice.

Advanced 10 + repetitions each side slowly repeated twice.

Variations

Bringing the legs together, so that the knees and ankles are aligned will reduce your stability throughout the movement, and as such will require greater muscular strength to perform and maintain the position.

Only suitable for intermediates and advanced, perform 10 - 15 slow repetitions each side, repeated twice.

Raising the top leg throughout the movement will again reduce stability, whilst also working the deep lateral flexion muscles. Alternatively extending your arms straight out above your head will increase the resistance. This method is an advanced exercise, perform suitable repetitions, stopping if you feel any discomfort, or if your technique becomes poor.