Speed Shoulders

I read this morning in an old book I had on Fitness about speed work. I didn't learn anything new but it reemphasized the importance of working those fast twitch muscles. So I did the following exercises at a really light weight:

Cable Lateral Raises: 4 x 4 x 10

Close Grip Pulldowns: 4 x 4 x 100
supersetted with
PullUps: 4 x 2

Shrugs: 4 x 4 x 135
supersetted with
DB Lateral Raises: 4 x 5 x 30

Close Grip Upright Rows: 4 x 5 x 95
supersetted with
Seated Wide Grip Cable Rows: 4 x 5 x 100

Not much rest between sets and these were really easy. Seems counterintuitive to do such light weight so few times. Kept in mind that it was speed work and am hoping that it does something.