How? I've never heard about it. It does sound little bit like sci-fi. So if we would start playing soccer with left leg (more than our leading right one) then our brain would also be stimulated in a way that can help us?

I have heard that before, it is not sci-fi, I really don't know why it works best for the brain. If you are right handed, try using your left hand to eat from time to time, it helps the brain a lot. It like learning a new language, because you are learning how to use a dormant hand or leg @crypto.piotr