The (other) AP has a neat article on the technology the Kansas City Chiefs are using during games. According to Dave Skretta, the Chiefs are using a device from StatSports which collects all kinds of data on a player during practice.
Basically, this little black device is put on a player's jersey and it can provide information about the player's activities that day, such as:
— Accelerations and decelerations, including peak rates, duration and distance covered.
— Heart rate, including max, average and the time a player spends at threshold.
— Step balance, which determines how much force a player applies to each foot, and can be used to determine whether a player is dealing with an injury.
— Dynamic stress load, the total force of weighted impacts that a player experiences during a practice, a more useful metric than running for offensive and defensive linemen.
The Panthers and Bengals are the only other teams using this particular technology but I have heard of the Eagles doing something similar, too. The Chiefs trainer is quoted in there as saying that the Chiefs monitor the results to see if they need to change their practice around in order to maximize the time that they have.
Check out the full article here. Neat stuff.