For the most explosive performance, you should define the ‘core’ muscle group as containing more than just the abdominal wall. To reap the real benefits of the true protection the core musculature promises, you should also add the obliques, spinal erectors, hip flexors and glutes. Spending time developing your core is smart because this muscle group will prevent you from getting hernias and save your lumbar discs from injury. Besides the importance of staying injury free, the core muscle group is responsible for all explosive power in both the weight room and the field/on the mat/in the cage. Its all inclusive role in virtually anything athletic gives credence to prioritizing it in every training program. The problem is most coaches and programs do not know how to train this muscle group properly for the best strength carry over into their particular sport and everyday life. With the wrong exercise selection and/or program set-up, you can waste tons of time and energy working your abs to death and barely doing anything more than keeping your mid-section fit but still leaving you with a pitifully weak core.
Many athletes brag how they do thousands of sit-ups and/or crunches every day. The fact is these exercises rarely do anything more than provide a bit more tone to your gut. To get the most power and stability from the core, use only exercises that have a strength carryover to the rest of the body. Bent leg exercises like these take the primary emphasis off the front abdominal wall and place it on the hip flexors. While training the hip flexors is a good idea, hundreds of reps all the time can lead to overtraining and eventually an imbalance. If the imbalance continues it can even lead to a postural spinal imbalance leading to further, more complicated issues and injuries. If you want a strong, healthy core, rarely practice abdominal exercises with bent legs. Choose exercises with straight legs for the best and most functional strength carry over. Examples of straight leg abdominal exercises include straight leg sit-ups, ab pull downs (using a cable machine/lat pull), leg raises, planks and hanging leg raises. If your exercise program doesn’t revolve around strengthening your core, you would be extremely wise to train your core directly at least once/week using these exercises.
Besides the wrong exercises, most trainers advocate high reps such as 20-30+ when performing abdominal work. This will only barely give you a fit mid-section but do nothing for enhancing your physical abilities. Remember what the core is used for… protection of your spine and organs while offering a base of explosive power for athletic movements. High rep work will not enhance this, however using light to moderate weights explosively for less reps will. To develop your core so it’s best fit for explosive power, provide resistance by holding weights or using bands and keep the reps in the 8-10 range for most of your training. For the best gains, keep records of how much weight you use and try to beat the numbers by volume/amount of weight each time you perform the exercise. Examples of good abdominal exercises with resistance include weighted straight leg sit-ups, incline straight leg sit-ups, leg raises with chains added to the ankles, weighted side bends and hanging leg raises with bands around the ankles (anchored to the floor).
Your core training should of course include plenty of work for the abdominal wall, but if you want the best stabilization and functional power, do more for your sides than your front. For real core strength, train the obliques twice and the abdominal wall once. Train the obliques with both side bends and twisting motions for both high and low reps however not more than 15 or less than 8. It’s also very smart to target the obliques with not only direct work but accessory lifts that heavily incorporate them. This includes one sided training like one legged squats, one arm overhead presses, one arm rows, one arm deadlifts and quite a few TRX exercises. Another great way to add functional strength to the core is by carrying heavy weights for a short distance. This is performed by carrying a heavy kettlebell, dumbbell or plate (more than 50 lbs.) at the chest level for 50-100 ft. Carrying weights with only one side is one of the best ways to train the obliques; these are called suitcase carries and performed exactly how they sound. Other great oblique exercises include heavy dumbbell side bends, handing side bends, offset bar bends (side bends with a squat bar offset on your back), anchored barbell work, twists with weights, med balls and hammers and wood choppers with cables or bands.
When you want improved performance, it’s important you keep your program varied with different exercises all the time. Performing the same exercise/rep scheme over and over again will only help a brand new beginner for a short period of time. Intermediate and advanced athletes must keep their training fresh by switching exercises all the time. Vary your program with different core exercises to give your system a hardiness for activity in every direction. Also include exercises to emphasize other posterior chain musculature like the glutes, lower back, upper back, traps and neck. These include kettle bell swings, adductor exercises, back raises, reverse hypers and tons of hamstring work with glute ham raises, good mornings and romainian dead lifts. Adding this emphasis to your program will greatly enhance your core work and ensure better carry over into other athletics.