When training to strengthen your core, you should begin by teaching your trunk how to stabilize itself first before moving onto strength exercises. As with any muscle, too much too soon could lead to injury — and an injury to your core is devastating to any training program. Once you have begun to build power and stability within your core, only then should you begin the core strengthening exercises. Don't forget to focus some of your attention to your pelvic floor; keep it slightly engaged by squeezing the buttocks together.

If you have these muscles properly engaged, you should feel a slight pull inward from your belly button. However, be sure that you do not over do this as internal strains can be quite painful. This pull should be a simple, subtle draw inward of your belly button. This is engaging your lower abdominal wall and transversus abdominis.

There are a couple of reasons it is important to strength train the core in this way. First, when holding the pelvic floor and core musculature together you are strengthening your body from the inside out. This is the deepest level of strength training that can be practiced. When this kind of strength is developed you will see an increase in strength in everything you do, from lifting your child into her car seat to your Krav Maga workout routines.

The second reason it's beneficial to train the core this way is that with practice your body will begin to make these muscles fire more frequently whether you are aware of them or not. You want this to become second nature to you, something you automatically do all the time. So when you punch and kick you may not be thinking about how the muscles in the core are firing, but they will be firing due to the fact that you train them. Thus your punches and kicks will naturally become stronger and more powerful.

Following are some exercises for core trunk stability.

Core Exercises

Plank

1. Start out on your hands and knees with your hands directly under your shoulders.

2. Step your feet back hip width apart so that you are holding the top of a pushup position.

3. If you are struggling to hold this position, step your feet wider than hip width to distribute the force over a wider base of support.

This exercise is static, which means that you do not move. Your body should be one straight line from your heels all the way up through the top of your head. The entire front body should work to support you.

Safety: Here's a tip to maintain a straight posture in Plank: Pretend there's a string tied at the base of your spine that runs up your back and is being pulled tight at the crown (top of head). This visualization is often helpful to avoid the beginner mistakes, such as drooping your midsection to the ground, lifting your head up, or arching your back. Also keep your navel pulled in slightly.

Yoga Pushup

1. While remaining in the Plank position, lower your body in one straight and solid piece all the way down to the floor. Brush your upper arms and elbows into your ribs as you lower.

2. Once lowered, press with your arms to push yourself back into your starting position (Plank).

3. Return to starting position. The idea is that you do not lose any stability in the trunk of your body as you lower yourself down and return to the starting position. Your arms have to do some of the work here, but try to see if you can make your legs and core take more of the force so that you don't feel as though all of the heavy exertion is being placed on your upper body. If you feel you cannot hold your body, continue practicing Plank and doing pushups on your knees until you feel like you are strong enough to move to pushups on your toes.

Side Plank

1. Assume a stable and straight Plank position, then step your right hand to a point on the floor that is under your nose.

2. Slowly rotate your entire body all the way to the left (counterclockwise). You must use the inner and outer edges of your feet to stabilize yourself. Your left foot is just in front of your right foot.

3. Next, place your left hand on your hip and take deep, controlled breaths. Once you have achieved balance, be sure that you are using your core by lifting your hips toward the ceiling.

4. Once you can do this with control and balance, try reaching your left arm up toward the sky. Lower the nonsupport (left) arm back down to the floor as you come slowly back into plank position.

5. Now switch sides. If the Side Plank is a little too much for you in the beginning, modify the pose by doing do it with one knee down on the floor. If you are looking to add a little more difficulty, try stacking your feet one on top of the other.

Core Resistance

Following are some core strength and resistance exercises:

Seated Balance

1. Sit with your feet out in front of you and knees bent.

2. Lift one foot up off the ground followed by the other.

3. Try to lengthen the spine and open up the chest.

4. With both arms parallel to the ground, turn the palms up and reach the arms forward.

5. Try holding for at least 5 seconds in the beginning, then build up to at least 30-second sets.

Straight-leg Sit-ups

1. Start seated with both legs straight and your arms reaching up toward the ceiling. Inhale.

2. As you exhale, reach your arms forward. Try to round your back down one vertebra at a time, while allowing the arms to move out in front of you.

3. Inhale as you reach your arms over your head.

4. Exhale as you reach your arms forward and peel your body up off the floor to come back to your starting position.

5. You can begin with 4–5 reps, and as you become stronger work up to 10–12 repetitions per set.

Cross Extensions

This exercise is a variation of the classical bicycle exercise.

1. Place your hands behind your head.

2. Without pulling on your neck, take your right elbow to your left knee.

3. Extend your right leg all the way out along the floor.

4. Alternate back and forth while keeping your shoulders from touching down between each repetition.

5. Start with a total of 10 repetitions and work your way up to 20–30. The slower you perform the exercise the fewer reps you will do until reaching a point of muscular fatigue.

Half Cross Extensions

1. Lay down on your back, face-up, with your right arm overhead and left leg straight along the floor.

2. As you exhale, touch your right hand to your left toe.

3. Inhale back into your starting position and repeat.

4. Be sure to perform the same amount of repetitions on both sides.

5. Begin with sets of 5–8 reps and build up to 8–12 reps per set.

Russian Twists

1. From a seated position, balance with your feet lightly touching the floor.

2. Rotate your torso and touch your hands to the floor on one side of you.

3. Reach your hands up and over to the other side.

4. Repeat 8–12 reps per set.

This exercise can also be done with a medicine ball or a hand weight for added resistance.

Knee Drive

1. From Plank, lift your right leg up and bring your knee in toward your chest.

2. This can be performed fast or slow, although it's much more challenging when done slowly.

3. Try to keep your shoulders over your wrists when bringing your knee forward.

4. Extend your leg back slowly and place your foot gently on the ground in order to move to the other side.

5. This may be challenging at first. Once you become stronger and more flexible this exercise will become much easier. Start with 6 repetitions per set and build up to 10–12 reps per set. Again, the slower you go the more challenging it becomes to do more repetitions.

Bridge

1. Lay face up, and bend your knees with your feet close to the buttocks and hip width apart. Try to keep your feet parallel to each other (although it may be hard to tell because you should not be able to see your feet).

2. Press the hips up with your legs. You can either hold this as a static exercise or you can lift and lower for repetitions.

3. Ground fighters do a variation of this exercise by rolling over one shoulder and reaching the opposite arm across and back (see the Bridge Variation photo).

4. This exercise should be done at least 8–12 times. You can do a static hold for 5–30 seconds as well.

Spinal Extension

1. Lay face down with your elbows in and your hands close to the shoulders.

2. As you inhale, lift your head, chest, and arms off the floor.

3. With an exhale, lower back down toward the floor. Many people look forward when performing this exercise. Keep the chin down so the back of the neck is long.

4. Repeat this 6–10 times.

Core Power

For any exercises in which you are training to increase the power in the core of the body, you should perform at least 10 to 15 repetitions and two to three sets of each exercise. Remember when training for power that the exercises are generally done faster than when training for stability or general strength. Keep all of the muscles in the trunk firm when performing any core exercises.

Sit-ups

When performing a sit-up to increase the power of the muscles in the trunk, it is best to anchor your feet either under a sit-up bench or any stable object you can fit your feet under or by using a partner to hold your feet.

There are many variations for the arms. The simplest version is with your arms across your chest. You then sit back so the lower to mid back touches the floor but the shoulders do not. This is different from a regular sit-up in that you are working on power, which means by using your legs to stabilize you can speed up the movement to increase the workload.

If that feels easy, try placing your hands behind your head, but be sure as you come up you do not pull your head forward to assist your situp. Lastly, you may hold a weighted ball at your chest or overhead to increase the resistance. Remember, whenever you add speed it should be just enough to also stay in control of the exercise in both directions, in this case sitting up as well as going back.

Double Leg Lifts

1. Lying on your back, find something to anchor your hands down with. You may grab your partner's ankles or the legs of a chair. Just be sure whatever you use is heavy enough that you do not lift it off the ground.

2. Take both legs up toward the ceiling, keeping your legs as straight as you can. Make sure your naval is moving toward your spine. If your hamstrings are tight, you may have to bend your knees to bring your legs to this position.

3. Inhale as you lower your legs down as far as you can without the spine moving from its starting position.

4. Your legs will come back up at the last half of your exhale.

Once you have found your range of motion you can begin to speed up the pace of the exercise. You may lose the stability of the spine slightly. This is probably fine for someone who has a healthy back and spine. However, if it bothers your back, slow down and only work through the range of motion that does not irritate your back or feel painful. Once you have built up some strength in the midsection you will find that your range of motion will increase.

Overhead Rotations

This is a great exercise to strengthen all of the muscles in the mid section of the body.

1. Stand with a medicine ball at your left thigh.

2. Reach the ball out to the left side, up over your head, and down to the right side.

3. Finish with the ball touching the right thigh and repeat in the opposite direction.

Crunch-ups/V-ups

This is an old gymnastics exercise. Once you are able to perform a Seated Balance, you are ready to try Crunch-ups.

1. From the Seated Balance position, inhale as you extend your legs out and exhale as you bring them back.

2. Start with your hands on the floor, just next to or behind your hips, then try holding your arms parallel to the floor.

3. Once you've mastered this, try the exercise with straight legs. The upper and lower body will both lower toward to floor without touching, you then come back up and reach toward the toes. This is called a V.

4. Drop back and burst up, staying balanced and finding a rhythm that works for you.