Core muscles are defined as any muscle that connects to the ribs, pelvis or lower back. There are 29 core muscles in all. Strengthening those muscles through exercise can improve overall physical condition. A strong core also provides body stability, makes it less susceptible to injury and better protects the back and spine. Core strengthening exercises will improve balance, posture and sports performance.

Some of the muscles that core strengthening exercises work include the hip-flexors, the muscles of the upper and lower back, and the abdominal muscles. They also include the muscles of the trunk and the hip and shoulder girdles.

Some easily accessible core strengthening exercises that do not require any special equipment include:

Abdominal crunches . Lying flat on your back with your knees bent and your feet flat on the floor, position your hands behind your neck with elbows bent. Raise your shoulders up off the floor moving them toward your knees. Slowly, and with control, lower your body back down to just above the floor and repeat. Reverse crunches are also an effective core strengthening exercise. Utilizing the same position, draw your knees up off the floor towards your chest using similar repetitions.

Plank. Lying flat on the floor with your face down, bring your arms into the position to do a simple push up. With your hands on the floor, raise your body off the ground until your arms are fully extended, although not hyper-extended. Tightening your abdominal muscles, hold this position for about 10 to 15 seconds and repeat. Planks can also be done in a side position resting on your bent forearm to work the oblique muscles which are also part of your core. A simple push up is also a good core strengthening exercise.

Bridge. Lying on the floor on your back with your knees bent and your feet flat on the floor, push your hips up while keeping your heels planted. Squeeze your hip muscles at the top of the motion and hold for about three seconds. Repeat the process. To provide more a more challenging bridge, do the exercise with one leg extended but parallel to the floor. Repeat the same number of repetitions with the other leg extended parallel to the floor.

Squats. Standing with your feet slightly apart, bend your knees while keeping your back straight. Lower your body until just before your knees extends beyond your feet. Push through your heels straightening your legs and return to your starting position.

Many yoga positions would also be considered core strengthening exercises. Exercises utilizing any of the 29 core muscles would fall into this category.