The core is composed of several groups of muscles including the transverse abdominus, pelvic floor muscles ,multifidus and diaphragm. These muscles work together to produce stability in the abdominal region as well as coordination of movements of the arms, legs, and spine. Engaging these muscles is something that is not done consciously so it is important to know how to contract them during exercise.
Core exercises strengthen the core muscles which abdominal,back and pelvic muscles. Strong core muscles allow you to do other physical activities with more ease and will help if you suffer from low back pain.
The first group are floor exercises that don't require much movement but put constant tension on the muscles As you get better at these exercises you will increase the duration that you are able to perform them.
The plank works your entire core and upper- and lower-body muscles. Lie down on your stomach. Lift your body off the floor with your forearms (elbows at 90° degrees) and your toes. Keep your body in a straight position (without arching your back) and hold for 30 seconds to one minute. Lift one foot in the air for added difficulty.
This exercise is the same as the plank, except that you are in a pushup position. The pushup plank works the core, chest and biceps. This is a great exercise to end your workout with; it will fully fatigue almost every muscle in your upper body.
The next group are dynamic exercises that require movement.
This is one of the most effective crunch workouts, as it hits all of your stomach muscle fibers at once. Assume a standard crunch position, raise your torso to a 45° angle, and then twist from side to side. For an advanced movement, extend your legs and pretend to peddle a bicycle while continuing to twist.
This exercise is one of the most challenging. Lie on your back with your arms extended and raise your legs until they are perpendicular to the floor. Slowly lower your legs to the side as low as you can while maintaining complete shoulder and back contact with the floor. Bring your legs back up to center and lower them to the other side
Swiss Ball Core Exercise
Plank on a Swiss ball
This is a variation of the static plank. There are two possible executions: You can place your forearms on the Swiss ball with your feet on the ground or you can place your feet on the ball with your forearms on the ground. Keep your abs and glutes tight, and do not arch your back. Hold this position as long as possible. Move the ball slightly from side to side for an advanced movement.
The lying glute pushup targets your butt and back muscles. Lie on your back with your feet resting on top of a Swiss ball. Push through your heels to raise your butt off the floor as high as possible. Form a straight line from your knees to your shoulders. Hold this position for 60 seconds.