The game may be the same, but the gear is different: This Saturday, as NFL prospects try to impress coaches at the Combine workouts, a few players will don smart shirts–souped-up sports attire that measures everything from players’ heart rates to g forces of acceleration.

Designed by Under Armour and Zephyr, this sophisticated shirt is called the Under Armour E39. It weighs less than 0.3 pounds and boasts a load of sensors that sit just below the athlete’s sternum; the sensors include a triaxial accelerometer, a heart-rate monitor, and a breathing-rate monitor. As an athlete practices, trainers can follow the player’s vital signs on their smartphones, laptops, or any other device that can receive Bluetooth data. As Wired explains:

“What we have is something very close to the body’s center of mass that’s measuring the accelerometry data from that center of mass,” Under Armour vice president Kevin Haley told Wired.com.

This smart shirt innovates trainers’ and coaches’ performance evaluation by allowing them to see exactly how runners accelerate–and whether a player’s stride can be improved to gain speed. It does this by separately measuring acceleration and direction change on the left and right sides of a player, ...