Not to stray too far off topic, but isn’t ground contact time, at least for an elite sprinter at max speed, simply a byproduct of speed? You go faster your foot spends less time on the ground. Assuming speed over ground remains the same, how can you reduce ground contact time without contacting farther back in the stride or toeing off sooner? If the force applied is greater, speed increases, therefore ground contact time is reduced. It may be semantics, but I see so many people talking about training to reduce ground contact time when, IMHO, the should be training to 1) apply more force per stride (power) and 2) applly at faster (RFD).