Core work-outs make a difference...

[OpethDrums]

i think both endurance and heavy work is good for your core. just depends on what you plan on doing with it. explosive power is only going to last a little while if you dont have muscle endurance

i like medicine ball work for the core. i think thats what you do for explosive power. not doing a decline sit-up with 2 45s on your chest

 

[Madmick]

I think they (Air Force Para-rescue/Combat Controllers) were looking for endurance. I heard the swim test was even worse than the flutter kick requirement.

What is the flutter kick requirement and what is the swim test?