overspeed training

Anyone here do overspeed training alot with the bungee cords with a partner. We were doing those 2-3x a week (for football) i feel it has totally screwed up my running form and feel that im may be running slower after 7 weeks of not doing proper speed work. is this possible and what do you guys think of these devices.

It will lead to serious injuries, trust me.

Search the board, theres been lots written on the negatives of overspeed.

Other than running with a tailwind or down a very, very slight downgrade (hard to find), I would avoid it. It does create all sorts of trouble with mechanics, ground contact time, rhythm, etc. Might have potential if it is carefully regulated but the speeds are typically too excessive to be of help.