Because we may collide when we are exercising, if the impact resistance of the lens is not good, it will easily break. Once the lens is broken, it will do harm to such a fragile organ as the eye, you know.
As for the technical principle, you can find it online. This is a picture I found on the Internet.
Similar to the principle of ordinary charcoal and diamond, the main reason is that the molecular structure is more compact and the impact resistance is 5.6 times that of the national standard. I have seen an experiment in which almost 400 kilograms of pressure is pressed on the lens, and the lens will not break.
Of course, it doesn't mean that sports glasses can only be worn during exercise. It has the performance that ordinary glasses should have, but its impact resistance is particularly outstanding. It can be used not only at ordinary times, but also during exercise.