It may seem silly and doubt the question myself but I've been watching these animes; Freezing and Freezing Vibraton which is centered on genetcially modified/engineered girls with genetic tissue called Stigmata. These tissues allow them to attain superhuman skills such as being extremely strong and fast. I was wondering if this would be able to do in the future? If people could be this genetically modified. If I haven't explained things well, which I'm sure I haven't then I suggest watching an episode of the show. They're each on Netflix.

I've not seen that show, but I can tell you that there are very solid restrictions on how strong a human can be -- limitations imposed by the properties of bone, cartilage and muscle. Although there is a little variation in muscle between individuals, and between species, all muscle fibre is capable of exerting pretty much the same stress. That means that the strength of a muscle is almost exactly proportional its cross-sectional area, and that is of course limited by the structure of the human body. So you could never have, for example, Captain America lifting a car above his head: there necessary amount of muscle simply won't fit on a human.