Our technology is very different from marker-based systems. Adding markers would mean designing a completely different system.
Good marker-based systems like Vicon have very high-res cameras and therefor are capable of tracking small nuances of movements.
For tracking really high speed athletic motions, you just need cameras with good sensors, like Logitech QuickCam Pro 9000, to minimize motion blur. Markersless mocap systems are generally believed to be good at tracking large motions like athletics. See
http://en.wikipedia.org/wiki/Motion_capture#Optical:_Markerless