I find that when I haven't worked abs/core for a while (eg 1-2 weeks), I am much much stronger doing an ab workout and can manage planks much better. If it has only been a few days, my abs give out really earlier, especially doing planks.
So, my question is, if I want to continue to build ab/core strength and get some good shape there, should I just do abs/core once per week so that I am strong when I do it? Or, should I work them 3 times per week (as recommmended by Cathe in her description of the new core workouts coming out) even though I don't fel strong?
Any thoughts?

So, my question is, if I want to continue to build ab/core strength and get some good shape there, should I just do abs/core once per week so that I am strong when I do it? Or, should I work them 3 times per week (as recommmended by Cathe in her description of the new core workouts coming out) even though I don't fel strong?
Any thoughts?