Thanks for the input . The Articles were quite extensive too best stuff on the web. There was a German scientist who has written a lot on eccentrics too but I can't remember his name,
I am actually quite weak at eccentric. I am using 100-110%. If I could use more (a lot of people will be able to ) I would.
I use 130-140kg and max 130kg. Loads of 120kg /130kg work quite well at the moment but I am hoping to improve a lot at them. The stupid Powerrack at the gym is set too close to the wall, so I can't get a hand-off. I take about 2-3seconds to lower 140kg.
The articles even suggest using 60-80% for 8-10sec lowerings. I might give that a go too.
They worked a lot better once half the reps from 20 to 10 overall reps.
The rest takes ages so it annoys people waiting for the rack.