Haha. I think he is trying to get his post count up, so he can send me a DM of a video of him doing suitcase carry.
Not the way to do it brother, that is how end up getting kicked off for spamming the board.
To answer your question. Most people train their core different than the rest of their muscles. Why? Because they don't know what the fuck they are doing. Do you build your quads, biceps, pecs, etc... doing isometric holds? No, you don't. You train them with concentric and eccentric movements and you train them with weight, heavy fucking weight. Start training your core like that and shit will even out.