I can over 90 seconds too. This is just first try. So, advanced must be for you for over 150 seconds?

90 Seconds was a piece of cake. And I don't vendors have a six pack. Not even close to one.

60 to 90sec?

10 mins is advanced!! 

I can do 60 secs plank tops. Im usually grunting by the time my timer hits around 45 though. Arms start to shake around 50. And im screaming inwardly between 50 sec and minute mark. One tip though, add side planks to your normal plank routine and see how you go. No breaks between though.

Idk how i feel about planks i feel like my shoulder stability gives out way before my core

Advanced: on your hands!!

+мιкαη тѕυмιкι yep!

+мιкαη тѕυмιкι and +Hanna P -this exercise is for me only to test progress (and maybe for better sex :) ). The real exercise is body saw - number 10 from picture here: http://darebee.com/workouts/abs-of-steel-workout.html - do 5-6 sets or more with contraction at end 5 times, each set. Really goooood :) 

Last time i try to do it in combination with 5 sets pull ins - was great six pack training!
 

+Eduard Dimitrov I love body saws! I use a foam roller

+Hanna P, roller is not the same thing, but, yes, is very good. 

how many times per day

+Eduard Dimitrov (Едуард Димитров) yes it is , you put your shins ON the foam roller and body saw , now THATS a work out!!

+Osama Saafan, if you speak about body saw - bottom right on picture here: http://darebee.com/workouts/abs-of-steel-workout.html 

I do it 1 times weekly (only), but I am very busy - I work 60 hours weekly and train only 2-3 times weekly. You can do exercises for ABS  2 or 3 times weekly if you want. But keep in mind: Great Abs are made in the Kitchen, NOT in the Gym. Diet is very important!

Full training contains: Min. 5 sets or more " body saw" - with contraction at last 5 reps .
5 sets "pull ins" (see it on http://darebee.com/images/workouts/abs-of-steel-workout.jpg )


More info here: https://plus.google.com/+EduardDimitrov/posts/iHGps66qBTU