JCash wrote:
core is useless unless you're really injury prone, just run.
I don't know, the best runners seem to have better control of their bodies, more flexibility and power in their hips and a better connection between arms and leg movements. Sure, they are fitter, which allows them to sustain a higher work rate, but they are also wasting a lot less energy at foot strike and are smoother and more powerful because of it.
Core strength might help with that coordination and energy absorbtion. Coe did it. Getting strong from knees to sternum as he said it. El Guerrouj did a lot of it. WEbb did (does?) a lot of it. Bekele does it. Geb does it. Ovett did it. Kenyans do it. Almost all top U.S. distance and middle nowadays do it. Galen does an hour of core a day. One hour. A day. Have you done an hour this week?.
Generally proffesionals have a lot more time on their hands, so can do 2-3 runs a day+core work (which doesn't really need to take away from mileage), but I guess the OP doesn't have that luxury.
The ability to absorb energy from the ground, generate power from the hips, and transfer power from the torso/arms through the hips all generate a longer, faster stride, and ultimately, faster running speeds and better economy. Look at all the best runners and their strides...it is impossible to generate that without incredibly strong (and flexible) hips-particularly the psoas muscles, deep glute muscles, other hip flexors and extensors, abductors and adductors.
Core is definitely not just situps, and its not just abs. Core has more to do with the hips than the abdominal muscles, and hips are what running is all about. Have you ever seen a great runner with unstable hips? That is really the biggest difference between the elite runners and the sub-elite. There is a lot of twisting and turning around the hips during fast running, and core work is a good way to minimze these injury-causing forces.