Did you know that your core includes 35 muscles that make up your back, sides, abdominals and hips?
When people think of core muscles, abs are the first to come to mind. However, your core includes a lot more muscles than your abdominals. In fact, it’s everything besides your leg and arm muscles. While your legs and arms do the work necessary to get you moving, the core does the stabilizing, initiating, and supporting throughout the process. Strong core muscles make simple physical activities easier, protect your spine, make you leaner, and improve your balance. Athletes who want to kick or punch hard need a strong, stable core behind the movement.
You can’t effectively strengthen your core with isolation exercises like the crunch. Crunches are great, but they only work your abdominals. If you want a strong core, focus on movements that target multiple 
muscle groups at once (like your abs, back, and side muscles) so your core is forced to stabilize your entire body.
Instability exercises that put your balancing skills to the test are highly effective at strengthening your core. Here are a few to try.
Side Plank
Work your abs, upper back, and shoulders with the side plank. To do this simple exercise, lie on the floor on your right side. Your body should be in a straight line and your left foot on top of your right. Place your right forearm or palm on the floor to support your body and raise your left arm up toward the ceiling. Tighten your abs and lift your hips off the floor. Hold for 15 to 30 seconds. Lower your body and switch to the other side.
Russian Twist
To do a Russian twist, sit on the floor, lean your upper body back, bend your legs, and—if possible—raise your feet off the ground. You can either hold a dumbbell, weighted plate, weighted ball, or an imaginary ball in your hands in front of you. Twist your upper body to the right, bringing the ball or weight over to the right, then twist to the left, bringing the ball or weight with you. Continue twisting from side to side.
Bird Dog
Strengthen your lower back muscles, build your core, and test your balance with the bird dog exercise. For this one, you’ll need to get on your hands and knees on the floor as if about to crawl. Slowly lift your right arm straight out in front of you. At the same time, extend your left leg straight out behind you. Hold this position a few seconds then lower them both to starting position. Now slowly lift your left arm and your right leg. Hold and lower. Continue alternating from side to side.
Liftoff
This exercise may seem awkward at first, but it’s highly effective at targeting your back, shoulders, abs, glutes, and hamstrings. Stand up straight and then lean over, bending at the hips so your upper body is parallel to the floor. Extend your arms down toward the ground. Then, raise both arms out to the side while lifting your right leg straight behind you. Lower your arms and leg until it’s a few inches off the floor. Repeat for a minute then switch legs.
Lunge with a Twist
A lunge with a twist not only works your legs but your core as well. Stand up straight and hold your hands in front of you. Holding a weighted ball or dumbbell is optional. Lunge forward on your right leg and lower your body until your right thigh is parallel to the floor. Once in this position, twist your upper body to the left. Return to the starting position, lunge forward on your left leg, and twist to the right. Continue alternating sides.
