Teams are working on a lot of proprietary stuff with different vendors, and new ones are coming in every year. However, most use tracking systems (such as ones by a company called Catapult) that can measure all the wear and tear on players in practice. The issue is that they are not allowed to use these in games, and games constitute most of the “load” placed on the best players. NBA teams have more games than practices, and the intensity of those games is also far greater.