Name a 'speed enhancement device' on the market, and I've probably tried it at some point in my career.  In fact, when I do a clinic, I carry a gym bag with all kinds of devices, surgical tubing, overspeed pulley cables, resistance belts, etc.  Also in that bag are a couple of parachutes. 

I no longer use any of these devices.  Of course, my original interest in these products would often become a point of interest in the local media.  I came across a recent comment from Mel Siff on one of my 'speed toys'--the parachute.

As Mel pointed out:

Even the use of parachutes during sprinting, to create drag, has not been proven to optimally improve running speed since it is non-specific to the speed, mechanics, and gait of sprinting without a parachute. Those who obtain  modest gains from parachute sprinting do so because the stress overload on the muscles caused muscular strength and growth to occur. They could, however, have received better results from a sensible, non-specific exercise
program that would not disrupt the specific skills of their normal running gait....

Mel was indeed correct.  But I thought you'd enjoy this picture.