Bruce Lee, above almost all else as far as fitness, was well regarded for his abs. Bruce Lee had a powerful, functional six pack that any guy would love to have. But more than his six-pack, I want to draw attention to his core. He didn't just have abs for aesthetics; Bruce Lee had a powerful core that wrapped from the sides of his six-pack to his back muscles.
Same thing if you look at Buakaw Banchamek, arguably one of the best K-1 fighters and definitely one of the best Muay Thai fighters of all time. He has a very distinguished six-pack, but you can clearly see his dense core muscles on the sides of abs. This core is what helped Bruce Lee to produce the frightening punch power that he did. Core power helps Buakaw to completely blow away larger opponents with his mighty kicks.
Training the core is fantastic for endurance and lifting as well. If you look at a model's physique as compared to a powerlifter's physique, you'll notice a clear difference. The model may have better looking abs than the powerlifter, even of the same weight, but you'll notice more often than not that the powerlifter has a thicker and stronger core to accommodate heavier weights.
Wrestling, boxing, baseball, soccer, martial arts, golf, and almost any physical sport can be brought to its peak if the athlete trains his or her core. If not, you'll be weak against competition; a weak core means that the stress on your body will transfer to your spine, joints, and tendons, increasing the chance of injury. A strong core will protect these parts, and allow you to put in much more force and endurance.
Everybody knows and loves the six pack. That's what people seek for abdominal training, and that's what most people think when someone talks about your 'core'. Your core muscles can actually be broken down into four parts: transverse abdominals, internal obliques, external obliques, and your abs.
Your transverse abdominals wrap horizontally around your midsection, and they provide great support for your spine. Your internal and external obliques, which wrap diagonally from your pelvis to your ribs, support your torso movements, and provide stability for your spine and pelvis. Your abs, you already know about those :)
So how do you train all those parts for a strong core? Well, deadlifting is a great place to start (or finish!) Deadlifts require full core activation to really get that lift all the way up, and it works well to strengthen your core. The wrestler's bridge can also work wonders for your core, because you aren't only supporting your weight with your neck, you're keeping it stable with your core.
The dragon flag, used notably by Bruce Lee and popularized by Sylvester Stallone in the Rocky movies, is a really tough core strengthening exercise. You have to bring your whole lower body up toward your torso, and you get that extra eccentric burn when you bring your torso back down. If you haven't tried this exercise yet, beware: it's not for the faint of heart. BUT, in the end it delivers. That delivery might be as painful has shoving carbon under pressure and thousands of degrees of heat, but in the end, even that carbon comes out a diamond.
And one exercise that I love for core work that I know a lot of you might moan about, is the plank. There are so many plank variations for various parts of the body, but every plank exercise has some effect on strengthening the core muscles a great deal. Side planks, normal planks, and a variation of the reverse plank that I like to call “the drawbridge” help so much with core activation (more on the drawbridge later ;))
So don't undermine yourself or your athletic ability; solidify your foundation with core training, and build on that foundation for a well developed muscular strength system.